From Watershed Ambitions to Parcel-Scale Retrofits: Rethinking Rain-Gardens in Climate Resilience Planning

1. Introduction

Urbanization has reshaped natural hydrological systems by increasing impervious surfaces and engineered drainage networks. Conventional stormwater management has often focused on conveying runoff away from urban areas as quickly as possible, contributing to degraded stream systems, reduced groundwater recharge, and increased flood risks (Walsh et al., 2005; Fletcher et al., 2015; Bonciarelli et al., 2025; Hong & Huang, 2025). In response, green infrastructure (GI) and nature-based solutions (NbSs) have emerged as alternative approaches that seek to integrate hydrological, ecological, and social functions within urban environments (Benedict & McMahon, 2006; Kabisch et al., 2017; Park et al., 2025).

Within these approaches, rain-gardens are among the most widely implemented forms of decentralized stormwater management (Osheen & Singh, 2019; Boguniewicz-Zabłocka & Łukasiewicz, 2025; Bonciarelli et al., 2025; Lemes de Oliveira et al., 2025). Typically designed as vegetated bioretention systems, rain-gardens manage runoff close to its source through temporary storage, infiltration, and pollutant removal (Dietz & Clausen, 2005; Hunt et al., 2008; Davis et al., 2009; Burszta-Adamiak et al., 2023). Beyond these hydrological functions, rain-gardens are increasingly promoted as multifunctional interventions associated with ecological, social, educational, and climate-resilience benefits (Wang et al., 2024; Jezzini et al., 2023; Slobodníková & Tóth, 2025; Zhu et al., 2025). This broader framing positions rain-gardens not only as stormwater-management devices but as components of contemporary GI and NbS strategies.

Although rain-gardens have received substantial scholarly attention, much of the literature has concentrated on their technical and hydrological performance, including runoff reduction, infiltration, groundwater recharge, peak-flow attenuation, pollutant removal, and water-quality improvement (Dietz & Clausen, 2005; Hunt et al., 2008; Davis et al., 2009; Ahiablame et al., 2012; Burszta-Adamiak et al., 2023; Dudrick et al., 2024). Comparatively less attention has been given to the institutional and social conditions through which rain-gardens are implemented, maintained, and sustained over time. Research on GI implementation identifies governance arrangements, institutional coordination, funding, maintenance responsibility, and stewardship as important influences on long-term functioning (O’Donnell et al., 2017; Shandas et al., 2019; Sharma & Malaviya, 2021; Razzaghi Asl & Pearsall, 2022; Gräf et al., 2023). These concerns are particularly important because continuing maintenance and stewardship can determine whether the physical infrastructure remains functional after implementation (Shandas et al., 2019; Sharma & Malaviya, 2021; Gräf et al., 2023).

A related gap concerns spatial scale. Rain-gardens are generally implemented as localized parcel- or site-scale interventions, while many of the objectives associated with GI, including watershed management, ecological connectivity, flood resilience, and climate adaptation, operate across broader spatial and governance systems (Roy et al., 2008; Meerow & Newell, 2017; Hansen et al., 2023; Lux, 2024; Hill, 2025; Potsiou et al., 2025; Song et al., 2025; Zhu et al., 2025). Recent scholarship therefore emphasizes the need to coordinate distributed interventions through landscape- and watershed-scale planning rather than assuming that the accumulation of individual projects necessarily produces broader resilience outcomes (Meerow & Newell, 2017; Hansen et al., 2023; Lux, 2024; Song et al., 2025). This scalar relationship between localized intervention and broader resilience ambitions remains insufficiently examined in rain-garden research.

This study examines these relationships in New Jersey, USA, through a qualitative case-study design that integrates stakeholder interviews, documentary analysis, and structured field documentation of 18 rain-garden sites across diverse institutional and landscape settings. Rather than evaluating rain-gardens solely as technical stormwater-management devices, the study investigates how they are conceptualized and operationalized within contemporary GI systems; how governance, stewardship, institutional coordination, and public engagement shape their implementation, maintenance, and long-term functioning; and how site- and parcel-scale interventions relate to broader watershed and climate-resilience ambitions. In doing so, the study examines rain-gardens as socio-ecological and institutional interventions whose functioning depends not only on physical design but also on the governance and stewardship systems through which they are implemented and sustained.

2. Literature Review

2.1. Rain-Gardens as Decentralized Hydrological Landscapes

Rain-gardens are among the most widely implemented forms of decentralized GI (Osheen & Singh, 2019). Typically designed as shallow vegetated depressions that collect, infiltrate, and temporarily store stormwater runoff, rain-gardens are frequently categorized as bioretention systems or stormwater best management practices (Davis et al., 2009; Burszta-Adamiak et al., 2023; Lemes de Oliveira et al., 2025).

Rain-gardens occupy an important conceptual position between engineered stormwater infrastructure and nature-based landscapes. Within contemporary GI frameworks, they are associated not only with hydrological management and blue-green infrastructures, but also with ecological, social, and climate-resilience objectives (Benedict & McMahon, 2006; Jezzini et al., 2023; Potsiou et al., 2025; Slobodníková & Tóth, 2025; Zhu et al., 2025). This multifunctional framing creates an important analytical question: how are these broader ambitions translated into the design, implementation, and management of rain-gardens in practice?

The hydrological performance of rain-gardens is well established in the literature, including their capacity to reduce runoff volumes, attenuate peak flows, improve water quality, and, under suitable site conditions, support groundwater recharge (Dietz & Clausen, 2005; Ahiablame et al., 2012; Dudrick et al., 2024). These benefits help explain their use across residential properties, schools, parks, roadsides, parking areas, and municipal grounds as distributed interventions that manage runoff close to its source (Dietz & Clausen, 2005; Davis et al., 2009).

Their widespread adoption reflects growing interest in distributed approaches to urban runoff management that can complement centralized drainage infrastructure (Fletcher et al., 2015). Yet their designation as green or nature-based infrastructure can obscure their strongly engineered character. Rain-gardens commonly rely on designed soil media, hydraulic sizing, overflow structures, underdrains where required, and pollutant-removal specifications (Davis et al., 2009). They therefore operate simultaneously as engineered stormwater devices and vegetated landscapes expected to provide ecological and social co-benefits.

This dual character creates a distinction between how rain-gardens are conceptually framed within multifunctional GI/NbS discourse and how they are operationalized through design, regulation, implementation, and management. Understanding contemporary rain-gardens therefore requires attention not only to what they are designed to accomplish hydrologically, but also to how broader GI and NbS ambitions are translated into implemented landscapes.

Despite substantial literature on technical performance, comparatively fewer studies examine the institutional and spatial implications of rain-garden implementation. This gap is particularly relevant to the cumulative role of site- and parcel-scale interventions within larger watershed and resilience frameworks and provides the basis for examining how rain-gardens are operationalized in New Jersey.

2.2. Stewardship and Maintenance

Long-term stewardship and maintenance are increasingly recognized as critical dimensions of GI implementation. Although rain-gardens may be presented as relatively self-sustaining once established, technical guidance and research show that they require continuing care and maintenance and may depend on institutional support and stewardship to sustain intended functions over time (Obropta et al., 2005; Shandas et al., 2019; Shuster et al., 2022; Adib et al., 2026).

Maintenance activities commonly include sediment removal, mulching, replanting, invasive species management, inspection, watering, and adaptive vegetation management (Obropta et al., 2005). Inadequate maintenance may contribute to vegetation decline, clogging, reduced infiltration, and aesthetic deterioration (Roy et al., 2008; Sharma & Malaviya, 2021). Thus, rain-garden functioning depends not only on initial design and construction but on continuing care after implementation (Bahrou et al., 2024).

Reliance on stewardship can create long-term management challenges. Volunteer fatigue, uneven institutional capacity, funding instability, and maintenance burdens can affect the continuity of GI and rain-garden initiatives (O’Donnell et al., 2017). The durability of a rain-garden, therefore, depends partly on whether responsibility for its care is clearly assigned and institutionally supported.

The social labor underlying GI and rain-garden implementation remains less developed in the literature than hydrological performance. In this study, stewardship is therefore examined as a form of ‘invisible infrastructure’: the continuing human and institutional capacity required to sustain visible physical infrastructure. Examining who assumes this responsibility, how it is organized, and what occurs when it weakens is central to understanding long-term rain-garden functioning (Sharma & Malaviya, 2021; Gräf et al., 2023).

2.3. Governance, Regulation, and Institutional GI Systems

Rain-garden implementation is embedded within governance systems involving regulatory agencies, municipalities, universities, nonprofit organizations, designers, property owners, and community stewards. GI implementation can require collaboration among planners, engineers, scientists, decision-makers, and community stakeholders, together with long-term monitoring and evaluation (Ahern, 2011). From this perspective, rain-gardens constitute not only physical infrastructure but components of socio-ecological governance systems.

In the United States, GI implementation has been strongly shaped by the Clean Water Act, National Pollutant Discharge Elimination System (NPDES), Municipal Separate Storm Sewer System (MS4) permits, and state-level stormwater regulations (Dhakal & Chevalier, 2017). Municipalities increasingly rely on GI to satisfy regulatory requirements concerning runoff reduction, water quality, and stormwater management compliance. Rain-gardens can therefore function simultaneously as environmental improvements and mechanisms through which regulatory objectives are implemented locally. As a result, GI functions not only as environmental infrastructure but also as a regulatory governance mechanism. GI implementation and effectiveness depend on institutional coordination and governance integration (Kitha & Lyth, 2011; Meerow & Newell, 2017; Razzaghi Asl & Pearsall, 2022).

Funding systems also shape GI and rain-garden implementation (O’Donnell et al., 2017). Grants, nonprofit partnerships, university collaborations, utility funding, and foundation support can influence whether projects are implemented and sustained (Dhakal & Chevalier, 2017). These issues are particularly relevant in fragmented governance environments. New Jersey is a home-rule state in which municipalities exercise substantial authority over land use and zoning within state and federal regulatory frameworks (Hoefer & Cron, 2022). Responsibilities for implementation, maintenance, monitoring, and funding may consequently be distributed among municipal departments, development actors, nonprofit organizations, and volunteer stewards. Such institutional fragmentation raises questions about how broader GI objectives are translated into individual projects and how responsibility is sustained after implementation.

2.4. Urban Green Space, Landscape Perception, and Public Aesthetics

Rain-gardens occupy an ambiguous position within urban green-space systems. Although GI is often associated with ecological and social co-benefits, rain-gardens may remain primarily hydrological installations with limited recreational or public-space functions (Bąk & Barjenbruch, 2022; Wang et al., 2024). Because they are vegetated infrastructure embedded within everyday urban and suburban landscapes, their appearance can influence public acceptance and stewardship. This is relevant to this research because most assessed rain-gardens of New Jersey are located in a suburban setting, shaped by picturesque and pastoral landscape ideals. Since the early suburban expansion of the 19th century, homeowner associations, office park managers, and public park directors have been making sure that the suburban landscape has a manicured appearance (Höfer, 2027). Mulched beds, clipped shrubs, and regularly cut lawns reflect the aesthetic ideal of a well-maintained residential community in a suburban landscape setting (Höfer, 2027).

Naturalized vegetation may be interpreted as neglected, messy, or poorly maintained when it conflicts with cultural preferences for manicured landscapes (Gobster et al., 2007; Meenar et al., 2020; Cholakis-Kolysko, 2022; Ge et al., 2023). Conversely, planting diversity and deliberate landscape composition can improve public perceptions of rain-gardens (Ge et al., 2023; Shi et al., 2024). The resulting tension between ecological planting objectives and conventional expectations of visible maintenance is relevant to stewardship because perceptions of neglect can influence public support and management practices (Church, 2015; Meenar et al., 2020; Cholakis-Kolysko, 2022; Ge et al., 2023). Aesthetics is therefore treated in this study not as an independent measure of rain-garden success, but as one dimension of the relationship among vegetation, maintenance, public acceptance, and stewardship.

2.5. Climate Resilience, Scale, and the Limits of Parcel-Scale GI

Rain-gardens are increasingly situated within broader climate-adaptation and resilience strategies because decentralized GI can contribute to runoff management and urban flood adaptation (Meerow et al., 2016; Jayasooriya & Ng, 2023). This framing introduces a fundamental issue of spatial scale: rain-gardens are generally designed and implemented at parcel or individual-site scales, whereas flooding, watershed degradation, ecological connectivity, and climate resilience operate across substantially larger spatial systems.

Contemporary resilience planning increasingly emphasizes landscape- and watershed-scale approaches that coordinate distributed hydrological interventions (blue-green infrastructure), ecological connectivity, and adaptation across spatial scales (Hansen et al., 2023; Lux, 2024; Song et al., 2025; Zhu et al., 2025). Yet the interventions through which these ambitions are implemented often remain spatially fragmented. As Meerow and Newell (2017) demonstrate, multifunctional GI planning must negotiate relationships among individual sites and broader urban systems (Meerow & Newell, 2017).

Parcel-scale rain-gardens are relatively easy to implement and may effectively manage localized runoff and drainage conditions, but the extent to which dispersed interventions collectively contribute to watershed-scale transformation is less clear.

The assumption behind distributed resilience is that a collection of small interventions can collectively contribute to larger-scale transformation. This scalar mismatch is a gap in the current GI literature and raises concerns about the limitations of parcel-scale NbSs under conditions of climate uncertainty and fragmented urban governance (Lux, 2024). Recent scholarship calls for integrated watershed-scale and landscape-scale approaches to link hydrological performance, ecological connectivity, climate adaptation, and governance coordination across spatial scales (Hansen et al., 2023; Lux, 2024; Song et al., 2025).

The relevant question is therefore not whether an individual rain-garden can provide local hydrological benefits (these are already well established) but how localized interventions relate to the larger spatial and institutional systems within which climate-resilience ambitions are articulated. This scalar relationship remains underexamined and provides an important basis for evaluating rain-gardens in contemporary GI planning.

2.6. Conceptual Synthesis and Research Gap

The literature demonstrates that rain-gardens are increasingly important within contemporary green infrastructure and nature-based solutions frameworks. However, three related gaps remain important.

First, a conceptual and operational gap exists between the multifunctional ambitions attributed to rain-gardens and their implementation in practice. Although contemporary GI and NbS discourse associates rain-gardens with hydrological, ecological, social, and climate-resilience benefits, much of the empirical literature continues to emphasize technical and site-scale performance. Less attention has been paid to how institutions, practitioners, and guidance systems translate these broader ambitions into the implementation of rain-gardens.

Second, an institutional and stewardship gap concerns what happens after implementation. Rain-gardens depend on governance arrangements, funding, institutional coordination, maintenance, stewardship, and, in public settings, acceptance of their landscape character. Yet these social and institutional conditions remain less developed in literature than technical design and hydrological performance. Understanding long-term functioning, therefore, requires examining the human and institutional infrastructure that supports physical intervention.

Third, a scalar gap exists between the localized scale of implementation and the broader environmental ambitions associated with GI. Rain-gardens are typically constructed as parcel- or site-scale interventions, while watershed management and climate resilience operate across larger spatial and governance systems. How dispersed rain-gardens relate to these broader ambitions, particularly under fragmented implementation and governance, remains insufficiently understood.

This study addresses these gaps by examining rain-gardens not only as hydrological BMPs but also as socio-ecological and institutional interventions shaped by hydrological objectives, governance arrangements, stewardship, public-facing considerations, and spatial scale. Interviews, New Jersey documentary sources, and structured field documentation are compared while preserving their distinct evidentiary roles; Dunnett and Clayden (2007) is used separately as a comparative conceptual source. The analysis is guided by three research questions:

RQ1. How are rain-gardens conceptualized and operationalized within contemporary green infrastructure systems in New Jersey?

RQ2. How do governance arrangements, stewardship practices, institutional coordination, and public engagement shape rain-garden implementation, maintenance, and long-term functioning?

RQ3. To what extent do parcel- and site-scale rain-garden interventions align with the broader watershed and climate-resilience ambitions associated with green infrastructure?

3. Methods

3.1. Research Design

This study adopted an interpretive qualitative case-study design to examine how rain-gardens are conceptualized, implemented, governed, maintained, and situated within contemporary green-infrastructure (GI) and climate-resilience practice in New Jersey, USA. The case was defined as contemporary rain-garden practice within New Jersey’s multi-actor GI system rather than as the technical performance of individual installations. This framing allowed rain-gardens to be examined as socio-ecological and institutional interventions shaped by hydrological and ecological objectives, design practice, governance arrangements, stewardship, public-facing considerations, and the spatial scales at which environmental objectives are pursued.

The research used a multi-source qualitative design integrating three complementary forms of evidence: semi-structured stakeholder interviews, documentary analysis, and structured field documentation. Each source served a distinct evidentiary purpose. Interviews provided practice-based accounts of planning, design, implementation, maintenance, stewardship, governance, and perceived performance; New Jersey professional, technical, and regulatory documents provided the institutional and normative framing within which rain-gardens are promoted and implemented; and field documentation provided researcher-recorded evidence of directly observable physical and landscape conditions at 18 sites. A separate international book was analyzed as a comparative contextual documentary source rather than as evidence of New Jersey conditions.

The design was aligned with the study’s three research questions. Evidence concerning rain-garden conceptualization and operationalization informed RQ1; stakeholder and documentary evidence concerning governance, institutional coordination, stewardship, maintenance, and public engagement informed RQ2; and evidence concerning implementation scale, watershed framing, climate resilience, and the relationship between localized interventions and broader environmental objectives informed RQ3. The analytical strategy, therefore, emphasized comparisons across actors, documents, and observable site conditions while preserving the distinct kinds of claims each source could support.

During several accompanied site visits, stakeholders also provided contextual information concerning implementation history, funding, design decisions, maintenance, stewardship, and past problems. Because this information originated from stakeholders, it was treated as stakeholder-derived contextual evidence rather than as an independent observational source. Physical and landscape conditions, by contrast, were recorded by the research team using a common field protocol and retained as researcher-recorded observational evidence. This distinction was maintained throughout the analysis to prevent conflation of stakeholder explanation and researcher observation.

3.2. Study Area and Case Selection

New Jersey was selected as the study area because of its extensive adoption and institutional support of rain gardens as a decentralized green infrastructure (GI) strategy for stormwater management, water-quality improvement, and climate adaptation. Climate change and increasing impervious cover are contributing to greater fluvial and pluvial flood risk in the state, where more than 60,000 properties are estimated to experience annual flooding (Hiss et al., 2019). This context has generated substantial institutional interest in GI and resilience planning. The New Jersey Department of Environmental Protection (NJDEP) supports rain-garden and GI initiatives, while implementation involves municipalities, universities, watershed organizations, environmental commissions, and NGOs. For example, the Rutgers Water Resources Program has supported the implementation of more than 125 rain-garden projects across the state during the past two decades (RCEWRP, 2026).

Participant selection. Interview participants were selected purposively based on their direct professional involvement in rain-garden and GI planning, design, implementation, maintenance, stewardship, governance, or environmental advocacy in New Jersey. Selection sought information-rich perspectives from different institutional contexts, including municipal government, environmental NGOs and associations, landscape-design practice, and watershed stewardship. Participants also differed in their operational reach: some worked primarily at the municipal or watershed level, whereas others represented organizations working across multiple watersheds or statewide. The purpose was to obtain complementary perspectives from practitioners involved in different aspects and scales of rain-garden practice rather than to construct statistically representative stakeholder groups. Additional participants with relevant expertise were identified through professional networks and referrals.

Field-site selection. The 18 field sites were selected purposively, informed by recommendations from interview participants and professional contacts familiar with rain-garden planning, design, implementation, maintenance, stewardship, or advocacy. These recommendations facilitated access to information-rich cases for which implementation and management histories could also be understood. The resulting sample provided variation in municipality, institutional and landscape setting, age, size, design configuration, management arrangement, and physical condition. It included rain gardens on municipal public property, educational campuses, transportation and streetscape settings, civic and institutional landscapes, and private or residential developments across multiple watersheds.

Importantly, recommendations were not limited to exemplary or successful projects. Stakeholders also identified sites known to have experienced maintenance or functional difficulties, including neglected and underperforming installations. In addition, the research team identified problems at several other nominated sites during field documentation. The sample, therefore, included both well-maintained installations and sites exhibiting different forms and degrees of deterioration or maintenance difficulty.

Stakeholder recommendations informed case identification and provided contextual knowledge but did not determine the assessment of site condition. Regardless of whether a stakeholder accompanied the visit, the research team recorded observable physical and landscape conditions using a common field protocol and analytically distinguished them from contextual information provided by stakeholders. The 18 sites were therefore used as a heterogeneous qualitative case sample to examine variation in rain-garden implementation, management, and stewardship, rather than as a statistically representative sample from which statewide prevalence or performance could be estimated.

3.3. Data Collection

Data collection comprised three complementary components: semi-structured stakeholder interviews, documentary analysis, and structured field documentation (Table 1). The sources were selected to address different dimensions of the research questions and were not assumed to be equivalent or fully independent forms of evidence. Interviews captured practitioner and organizational perspectives; documentary sources captured professional, technical, regulatory, and comparative conceptual framing; and field documentation captured directly observable conditions of implemented rain-gardens.

Semi-structured interviews were conducted with ten stakeholders, each participating in their professional capacity: two municipal officials, four representatives of environmental NGOs, two representatives of statewide environmental associations, one landscape architect/designer, and one watershed steward. The participant set, therefore, represented different institutional roles and operational reaches. Institutional role and geographic scope were treated as analytically distinct: for example, some NGO/association participants worked across multiple basins or statewide, while municipal participants operated primarily at the local level and the watershed steward contributed a watershed-oriented perspective. The study did not treat these categories as statistically comparable groups; rather, their diversity provided contrasting practice-based vantage points for qualitative comparison.

All interviews were conducted online using a common semi-structured interview guide. The guide provided consistent core domains while allowing follow-up questions responsive to each participant’s professional role and experience. Core domains addressed rain-garden effectiveness and perceived co-benefits, aesthetics and public acceptance, maintenance and responsibility, and awareness, policy, and implementation. Hydrology, ecology, stewardship, governance, funding, monitoring, public perception, and climate resilience were explored through these questions and follow-up discussions where relevant. Interview questions were provided approximately one week in advance. Interviews lasted approximately 55 minutes on average, were recorded with informed consent, and were subsequently transcribed. Participants could decline individual questions or discontinue participation.

Document analysis was undertaken to characterize the professional, technical, institutional, and regulatory framing of rain-gardens. New Jersey-specific sources included: (1) nine professional lectures addressing GI and rain-garden planning, design, implementation, maintenance, and climate resilience; (2) one lecture by an NJDEP representative addressing environmental and regulatory aspects of rain-gardens; (3) two technical guidance documents, the Rain-garden Manual for New Jersey (2005) and the Green Infrastructure Guidance Manual for New Jersey (2015); and (4) the Stormwater Management Rules (N.J.A.C. 7:8, amended January 20, 2026). These materials were treated as documentary evidence of professional, technical, and regulatory framing rather than as observations of site conditions.

To provide a broader conceptual and comparative reference, the analysis also included Dunnett and Clayden’s Rain Gardens: Managing Water Sustainably in the Garden and Designed Landscape (2007). The book was selected because it offers an early comprehensive treatment of rain-gardens that integrates hydrological, ecological, planting-design, aesthetic, experiential, and stewardship dimensions across international examples. It was subjected to a separate structured qualitative thematic content analysis using domains corresponding to the study’s analytical framework: hydrological operationalization; ecological aspirations; stewardship; governance and institutional coordination; urban green space, aesthetics, and public perception; and climate resilience and scale. Within each domain, relevant textual evidence was identified and interpreted to establish the conceptual framing represented in the book. The resulting thematic profile served as a comparative conceptual benchmark for examining how contemporary New Jersey evidence aligned with, extended, qualified, or differed from broader rain-garden principles. The book was not treated as primary empirical evidence of New Jersey practice and was not used to establish or corroborate claims concerning New Jersey site conditions, governance arrangements, or implementation outcomes. The structured book analysis is reported separately in Supplementary Table S1.

Field documentation was conducted at 18 site records representing different municipalities, settings, ages, sizes, design configurations, and maintenance conditions (Table 2). Several site records contained more than one individual rain-garden. Some visits were facilitated or accompanied by representatives of NGOs, municipal government, or the design profession. During these visits, stakeholders provided contextual and operational information that could not be determined through visual inspection alone, including implementation history, funding sources, design rationale, maintenance arrangements, stewardship practices, past problems, modifications, and changes over time. This information was retained as stakeholder-derived contextual evidence and was not treated as independent corroboration of interview data.

Physical and landscape conditions at each site were recorded by the research team using a common field-documentation protocol. Recorded attributes included site setting and geometry; drainage and catchment context; visible ponding; erosion and physical degradation; inlet, outlet, and overflow features; infrastructure and surface materials; drainage direction; vegetation composition and cover; invasive or spontaneous vegetation; and observable maintenance condition. Consistent photographic documentation was also collected. These observations enabled a structured comparison of directly observable conditions across the 18 site records. They did not constitute continuous hydrological monitoring, ecological performance measurement, or a quantitative assessment of runoff reduction.

3.4. Ethical Considerations and Data Confidentiality

Interviews were conducted with participants in their professional capacities to obtain practice-based information concerning the planning, implementation, operation, maintenance, and stewardship of rain-gardens, rather than personal information about the participants. Prior to participation, interviewees were informed of the study purpose and procedures, the voluntary nature of participation, and the recording of the interviews. Informed consent was obtained before recording, and participants could decline to answer individual questions or discontinue participation at any time. Participant names and personal identifiers were excluded from the analytical dataset and manuscript and replaced with stakeholder codes (NG01–NG06, MU01–MU02, LA01, and ST01). Organizational affiliations were generalized to further protect participant confidentiality and reduce the potential for deductive identification. Interview recordings and transcripts were retained for research purposes and stored on password-protected devices accessible only to the research team.

A Rutgers University Non-Human Research Self-Certification was completed for the study, which classified the project as Non-Human Research under 45 CFR 46.102(d).

3.5. Data Analysis

Analysis followed a qualitative thematic content-analysis strategy within the interpretive case-study design. Interview transcripts and documentary materials were coded by one researcher through a systematic, iterative process. Because the analysis was conducted by a single coder, inter-coder agreement statistics were not calculated. Analytical consistency was supported instead through repeated review of coded material, consistent use and refinement of a common coding framework across comparable sources, retention of source-linked evidence within coding matrices, and structured comparison of interpretations across participants, actor contexts, documentary sources, and field records. The process was iterative rather than divided into a fixed number of coding rounds, progressing from individual/source-level examination to thematic organization, cross-actor comparison, and finally cross-source synthesis.

The coding framework combined deductive and inductive logic. Initial domains were derived from the research questions, study objectives, interview guide, and recurring issues in the professional and technical materials. These domains addressed hydrological operationalization and perceived performance; ecological aspirations and site constraints; maintenance and responsibility; stewardship and social acceptance; governance, funding, and institutional coordination; aesthetics and public perception; and climate resilience and scale. During close reading of individual interviews and documents, additional codes, distinctions, and counterexamples were retained when they emerged from the material. The relationships among these analytical domains, the research questions, and the evidentiary contribution of each data source are summarized in Table 3.

Interview analysis began with each participant as an individual source so that distinctive accounts were retained before aggregation. Coded evidence was then organized in comparative matrices by institutional/actor context, including municipal practitioners, NGO and association representatives, the design professional, and the watershed-steward perspective. Actor category was kept analytically separate from operational/geographic reach: some participating organizations worked locally, others across watersheds or regions, and some associations operated statewide across multiple New Jersey basins. Cross-actor comparison was therefore used to identify convergence, divergence, qualifications, and differences in emphasis associated with institutional position and operational reach, not to compare statistically equivalent groups. The analysis emphasized the content and relationship of perspectives rather than code frequencies; numerical occurrence of codes was not interpreted as prevalence or representativeness.

New Jersey documentary materials were coded using corresponding analytical domains so that professional, technical, and regulatory framings could be compared with practitioner accounts while retaining their distinct evidentiary status. The documentary analysis examined what functions and objectives were emphasized, how implementation and maintenance responsibilities were framed, what governance or regulatory mechanisms were articulated, and how scale and climate resilience were addressed. Agreement between documentary and interview evidence was not assumed; points of convergence, omission, tension, or difference were retained as analytically meaningful.

Dunnett and Clayden (2007) was analyzed separately as a comparative contextual document. Its structured content analysis examined six corresponding domains: hydrological operationalization; ecological aspirations and fragmented ecologies; stewardship; governance, funding, and institutional coordination; urban green space, aesthetics, and public perception; and climate resilience and the limits of parcel-scale intervention. Evidence was extracted and interpreted within each domain to produce a thematic profile of the book. This profile was used only as a conceptual comparator when interpreting the New Jersey evidence. It was not pooled with the New Jersey empirical material, counted as a participant/data case, or used to verify claims about New Jersey implementation, governance, maintenance, or site condition.

Field documentation was analyzed as structured observational evidence rather than coded as interview text. Site records and photographs were reviewed comparatively using the common field categories summarized in Table 2, including drainage and catchment configuration, visible ponding, erosion and degradation, vegetation condition and cover, invasive or spontaneous vegetation, and apparent maintenance condition. These observations were then brought into the thematic analysis where they addressed phenomena that were directly observable. Field evidence could therefore corroborate, qualify, or complicate interpretations concerning visible site condition, but it was not used to verify stakeholder explanations of implementation history, funding, governance, or other processes that could not be independently observed, nor to infer hydrological or ecological performance that was not measured.

Stakeholder-provided information obtained during accompanied visits remained classified as stakeholder-derived contextual evidence. This separation was important because stakeholder explanations provided during site visits were not treated as an additional independent source when they originated from the same participant. Researcher-documented site conditions, however, retained a distinct observational role because they were documented using the field protocol regardless of whether a stakeholder was present. This source distinction was maintained in the comparative matrices and in the interpretation of findings.

The final analytical stage used structured cross-source synthesis. For each major theme, interview evidence was considered alongside relevant New Jersey documentary framing and, where directly comparable, field-observed conditions. The purpose was not to require agreement among sources but to examine where evidence converged, where one source qualified or complicated another, and where divergence revealed differences between institutional intentions, practitioner experience, and observable site conditions. Claims were bounded by evidentiary type: interviews supported interpretations of practitioner and organizational perspectives; New Jersey documents supported interpretations of professional, technical, and regulatory framing; field documentation supported claims about observable conditions during the study period; and Dunnett and Clayden (2007) provided comparative conceptual context only. This analytical sequence generated the thematic structure used in the Results and Discussion and linked the evidence directly to RQ1–RQ3.

3.6. Limitations

As an interpretive qualitative case study, the research was designed to develop an analytical understanding of rain-garden conceptualization, implementation, stewardship, governance, maintenance, and scale rather than to estimate conditions or outcomes for all rain-gardens in New Jersey. Purposive recruitment and site selection supported by professional networks and referrals provided access to information-rich participants and sites across different institutional settings and operational reaches. Because field sites were drawn from installations known within participating professional and institutional networks, the sample does not represent all rain-gardens in the state. However, recommendations were not restricted to successful or exemplary installations. Three visited sites were identified by stakeholders as neglected, and two as underperforming, and stakeholders openly discussed maintenance difficulties, stewardship challenges, and causes of deterioration. The research team also documented additional problems at several sites, including clogging, erosion, invasive or spontaneous vegetation, vegetation decline, and physical degradation.

Stakeholder involvement in some site visits strengthened contextual understanding of implementation history, maintenance, funding, stewardship, and governance, but did not determine the researchers’ assessment of observable conditions. Contextual explanations were treated as stakeholder-derived evidence, whereas physical and landscape indicators were recorded by the research team using the common field protocol. Accordingly, only the researcher-recorded documentation was treated as a distinct observational source; stakeholder explanations provided during site visits remained part of the stakeholder evidence.

The participant set included municipal practitioners, NGOs, and associations with regional or statewide operational reach, a design professional, and a watershed steward. These perspectives broadened the institutional and scalar range of the interview evidence, but they were not sampled as equal or statistically representative stakeholder populations. Accordingly, cross-actor findings are interpreted as qualitative patterns, contrasts, and perspectives within the cases examined rather than as estimates of the prevalence of particular views among New Jersey organizations.

The 18 field-documented site records spanned multiple municipalities, counties, watersheds, settings, ages, and maintenance conditions but did not constitute statewide geographic coverage. Field observations documented conditions visible during the study period and did not include continuous hydrological monitoring, runoff-reduction measurement, longitudinal ecological assessment, or direct surveys of site users. Consequently, field evidence supports the interpretation of observable site conditions and landscape characteristics, while claims concerning long-term technical performance, causal processes, or public preferences remain outside the scope of the study. The findings should therefore be understood as an in-depth, analytically transferable account of the cases and institutional perspectives examined rather than a statewide assessment of rain-garden prevalence, condition, or technical performance.

4. Results and Discussion

The Results and Discussion are organized around the principal themes developed through the qualitative thematic content analysis and cross-source comparison. Section 4.1 and Section 4.2 address how rain-gardens are conceptualized and operationalized; Section 4.3, Section 4.4 and Section 4.5 examine stewardship, governance, and public-facing dimensions of implementation; and Section 4.6 examines the relationship between localized implementation and broader watershed and climate-resilience objectives. Within each theme, stakeholder perspectives are considered alongside New Jersey-specific documentary evidence and, where directly comparable, field-observed conditions. Convergence, divergence, and differences among sources and institutional perspectives are retained as analytically meaningful rather than treated as inconsistencies requiring resolution.

4.1. Hydrological Operationalization of Rain-Gardens

Across the interviews and New Jersey-specific documentary sources, rain-gardens were predominantly conceptualized as decentralized stormwater-management infrastructure. Recurring objectives included infiltration, localized runoff reduction, groundwater recharge where site conditions permit, stormwater storage, pollutant removal, and flood mitigation. Reviewed documents described rain-gardens in relation to stormwater management, best management practices (BMPs), watershed runoff, impervious surfaces, and MS4 compliance. This emphasis was also explicit in the interviews. As one municipal participant stated, ‘the main value of them is being Stormwater Best Management Practices (BMPs)’ (MU01). Recreational and social functions within urban green space received comparatively less emphasis.

Within the interview evidence, rain-garden implementation was most commonly described through site- and parcel-scale projects, many of which involved retrofitting existing developed landscapes, although participants also identified examples incorporated into original site designs. Interviewees repeatedly described rain-gardens as “site-by-site,” “school-by-school,” and “property-by-property” projects located at libraries, schools, parks, curb extensions, municipal buildings, parking lots, and residential properties. Similarly, the reviewed documents reinforced this localized retrofit logic to specific sites. They emphasized retrofitting tools such as disconnected impervious surfaces, curb cuts, underdrains, and engineered soil media to promote infiltration and provide stormwater storage. Provided plans illustrated hydrological calculations and demonstrated how the tool supports flood mitigation measures.

The analyzed documents contrasted rain-gardens with conventional gray stormwater systems, particularly centralized conveyance approaches that provide fewer opportunities for local retention and infiltration. They presented GI as an approach intended to better approximate predevelopment hydrology, while rain-gardens were described as site-scale interventions that can slow runoff, promote infiltration, reduce peak flows, and reconnect local hydrological processes where site conditions permit. Interview accounts likewise emphasized adaptation to local soil conditions. One municipal participant noted that ‘Clay soil is a challenge sometimes. Bioengineered soil is used to enable percolation at a faster rate’ (MU01), illustrating the interaction between hydrological objectives and site-specific engineering requirements.

The findings also reveal an important scalar tension. Although documentary and interview evidence referred to watershed-scale resilience and regional hydrological planning, implementation was described predominantly through localized projects. Rain-gardens and related GI measures can address runoff and drainage at individual sites, while watershed flooding, hydrological degradation, and climate-related precipitation changes operate at larger scales. Several interview participants articulated a cumulative logic for distributed site-level interventions while also recognizing the need for broader coordination. As representatives of a statewide environmental association explained, ‘We work by watershed. We install as many rain-gardens as possible in each watershed’ (NG03). Their account linked the strategic accumulation of individual rain-garden and other GI projects to broader watershed water-quality objectives without implying that site-scale interventions alone constitute watershed-scale treatment.

4.2. Ecological Aspirations and Fragmented Ecologies

New Jersey-specific documents framed rain-gardens as having ecological co-benefits that can include native planting, pollinator habitat, biodiversity support, and environmental education. They also described demonstration landscapes through which schoolchildren and the public can encounter native plants and ecological processes. Interview participants recognized these ecological and educational functions. As one municipal participant explained, ‘we think of them as pollinator habitats, improving water qualities, ecological examples, educational precedents, and water management strategies…However, the main value of them is being Stormwater Best Management Practices (BMPs)’ (MU01). Across most implementation-focused interviews, ecological benefits were discussed primarily in terms of native planting, pollinator habitat, environmental education, and site-level enhancement rather than connected habitat networks. The watershed stakeholder offered a broader perspective, arguing that ecological benefits could be amplified at watershed scale through efforts to ‘connect habitats,’ daylight streams, and increase urban green space (ST01).

Within the implementation-focused interview evidence, ecological objectives were generally articulated as complementary to the dominant stormwater-management rationale rather than as independently developed landscape-scale objectives. Participants commonly discussed ecological benefits at the individual-site scale, whereas integrated habitat networks and corridor-scale ecological planning received comparatively little attention. This pattern is consistent with the site- and parcel-scale character of the rain-garden interventions examined, but the study does not attribute it to site size alone.

Similarly, interview discussions of maintenance focused primarily on drainage function, vegetation survival, and the practical requirements of upkeep. Habitat connectivity and ecosystem-scale restoration were rarely raised in implementation-focused accounts. Participants recognized that stormwater problems operate at watershed scale and described distributed rain-gardens as incremental measures that can contribute to broader hydrological objectives. Ecological benefits were most often articulated through planting, pollinator habitat, and environmental education rather than corridor-scale integration or landscape-scale biodiversity planning. The evidence therefore suggests that ecological objectives are present but are typically operationalized through site-level landscape features within a predominantly stormwater-management framework.

Watershed-oriented programs provided a broader rationale for distributing rain-gardens and other GI measures across areas such as the Delaware and Raritan basins. Within the evidence examined, however, watershed targeting was discussed primarily in relation to stormwater and water-quality objectives; explicit ecological-network planning received less attention.

As a comparative documentary source, Rain Gardens (Dunnett & Clayden, 2007) places greater emphasis on ecological and landscape dimensions than the New Jersey-specific implementation materials examined in this study. The book presents rain-gardens as opportunities for biodiversity enhancement and habitat creation and advocates diverse planting strategies, layered vegetation, and reduced reliance on lawn monocultures. It therefore extends their role beyond stormwater management toward broader ecological functions. Dunnett and Clayden suggest that ecological value can be influenced by vegetation structure and spatial complexity rather than relying exclusively on native species, and they discuss rain-gardens and water-retention landscapes as potential wildlife habitats. This reflects a broader conception of urban ecology in which habitat value may emerge from diverse and carefully designed planting arrangements. At the same time, the book gives limited attention to habitat connectivity, ecological corridors, or landscape fragmentation. Consequently, its examples provide less insight into the cumulative ecological contribution of dispersed rain-gardens at broader landscape scales. This limitation appears partly related to the predominantly localized nature of the examples presented and the limited consideration of connected ecological networks.

Taken together, the interviews and New Jersey-specific documents show awareness of larger ecological and hydrological systems, while the implementation discourse remains predominantly hydrological. Native planting, soil systems, and vegetation were often discussed in relation to infiltration, soil stabilization, pollutant removal, pollinator habitat, and environmental education. Rain-gardens therefore emerge in the New Jersey evidence as engineered stormwater landscapes with ecological co-benefits rather than as components of an explicitly connected ecological network. By comparison, Dunnett and Clayden (2007) place greater emphasis on ecological and landscape expression, although their examples likewise provide limited treatment of landscape-scale habitat connectivity.

4.3. Stewardship as Invisible Infrastructure

One of the strongest patterns across the interview and New Jersey documentary evidence is that rain-gardens function as stewardship-dependent infrastructure: their continued condition and functioning depend not only on physical design and vegetation but also on sustained maintenance, institutional support, and social organization. Although rain-gardens are promoted as relatively low-maintenance NbSs, the New Jersey documentary sources and stakeholder accounts indicate that their establishment phase requires careful management, including weeding, vegetation establishment, seasonal cutbacks, and occasional watering during droughts. Their long-term condition depends less on installation alone than on continuous maintenance, monitoring, institutional support, volunteer engagement, and social organization. Interview participants expressed similar views, often describing rain-gardens as opportunities to support local ecology, improve neighborhood environments, and create educational and pollinator habitats. This dependence was stated particularly clearly by NGO participants. One participant described having a committed adopter who would treat the rain-garden “like its their own garden” as “probably the ideal situation” (NG05).

New Jersey manuals and professional lectures similarly emphasize vegetation management, periodic inspection, and maintenance planning as important components of successful rain-garden implementation. The broader comparative literature reinforces the social dimension of this finding. Dunnett and Clayden (2007), for example, associate rain-gardens with environmental stewardship and community pride and position their management within broader goals of environmental awareness and community engagement. Taken together, these sources suggest that the continued ecological and social value of rain-gardens depends not only on their initial design and installation but also on sustained human involvement.

Recognizing the importance of stewardship and proper maintenance, some municipalities included in the study oversee maintenance and support stewardship efforts. The same concern was evident in NGO practice: representatives of two NGOs reported that they would not proceed with rain-garden installation without prior commitment from stewards to assume ongoing maintenance responsibilities. As one NGO interview explained, “we do not proceed with constructing a rain-garden unless there is an explicit commitment from a responsible party to maintain it over time” (NG01).

A notable point of agreement across the New Jersey interviews and documentary evidence is that stewardship is not supplementary to rain-garden functioning but integral to its long-term viability. Participants repeatedly identified neglected maintenance, volunteer fatigue, limited expertise, and resource constraints as major threats to long-term success. The vulnerability of volunteer-based systems was expressed directly by one NGO participant: “Some people will volunteer for a year, a season or two, but then they gradually lose interest and drift away from the rain-garden responsibilities” (NG06). A municipal participant similarly observed that “Sometimes these gardens are established and become forgotten, with little follow-up and maintenance” (MU02). Researcher-documented field conditions were consistent with these concerns: noticeable differences were observed in vegetation condition, weed pressure, bare areas, and overall maintenance condition among the documented rain-garden sites. These observations do not independently establish the causes of those differences but demonstrate the variable maintenance and vegetation conditions present across the field sites.

The findings collectively indicate that stewardship functions as a form of invisible infrastructure for rain-gardens. Although rain-gardens employ ecological and hydrological processes characteristic of NbSs, their long-term functioning within managed urban landscapes remains dependent on continuing maintenance and stewardship. Their success relies not only on soils, vegetation, and hydrological design, but also on the human networks and institutional arrangements that maintain and support them over time.

4.4. Governance and Institutional Coordination

Interviews and New Jersey-specific documentary sources indicate that funding, design, and implementation of rain-gardens depend on the coordinated efforts of multiple stakeholders. This coordination occurs across multiple institutional scales and involves federal and state agencies, the Rutgers Water Resources Program, municipalities, watershed organizations, environmental commissions, schools, foundations, NGOs, and community groups. These actors contribute different capacities and resources across the rain-garden implementation process, including planning, technical expertise, design, funding, construction, planting, management, stewardship, and maintenance. The evidence, therefore, indicates that rain-garden implementation in New Jersey operates through partnerships among technical experts, public agencies, nonprofit organizations, and community actors rather than through the responsibility of a single institution. New Jersey manuals and professional lectures similarly address this institutional context through MS4 permits, NJPDES requirements, watershed planning, GI strategies, and climate resilience planning. These documentary sources were broadly consistent with the institutional and governance issues identified by interview participants.

New Jersey’s regulatory framework has progressively strengthened the integration of stormwater management and green infrastructure into development planning. The Stormwater Management Rules (N.J.A.C. 7:8) establish stormwater-management planning and design requirements for applicable development and require stormwater management plans and control ordinances to, among other objectives, “minimize, to the extent practical, any increase in stormwater runoff from any new development” (N.J.A.C. 7:8-2.2(a)2). The rules also establish mandatory stormwater-management standards for new major development, including requirements addressing groundwater recharge, stormwater runoff quality, and runoff quantity. Under the green-infrastructure provisions, applicable major development projects are required to meet these standards through green infrastructure practices. Rain-gardens, as described in NJDEP guidance as small-scale bioretention systems, are among several GI practices that can be used to meet applicable stormwater-management requirements. The rules were most recently amended as part of the NJPACT/REAL rulemaking, adopted on January 20, 2026, which further incorporated climate resilience into New Jersey’s stormwater management framework (NJDEP, 2026, N.J.A.C. 7:8).

Interview participants identified several institutional constraints, including staffing shortages, limited municipal capacity, monitoring and maintenance demands, and administrative requirements associated with permitting and compliance. Funding was particularly prominent in NGO accounts. One participant stated, ‘There needs to be funding. This is at the top of the list’ (NG05), while another described replacement of major grant funding as a central concern for future implementation (NG04). Across these accounts, the capacity to expand and sustain rain-garden programs was linked to continuing institutional support, staffing, expertise, and investment.

Governance receives less explicit attention in Dunnett and Clayden (2007) than design, planting, and water-sensitive landscape principles. Although the book includes examples from public, commercial, and municipal settings that necessarily involve multiple actors, funding mechanisms, institutional capacity, maintenance responsibility, and governance arrangements are not developed as central analytical themes. This contrast helps distinguish the book’s comparative conceptual role from the governance-focused New Jersey evidence examined in this study.

4.5. Urban Green Space, Aesthetics, and Public Perception

The interviews, field observations, lectures, manuals, and guidance materials suggest that rain-gardens occupy an ambiguous position within urban green-space systems. New Jersey guidance presents them as landscapes that can enhance environmental awareness, appearance, and outdoor learning while retaining stormwater management as their primary purpose. Interview participants similarly emphasized hydrological functions more consistently than recreation or public use.

Field observations documented rain-gardens integrated into parking areas, municipal grounds, schools, libraries, streetscapes, parks, and institutional properties. Most were configured primarily as stormwater landscapes rather than recreational destinations. A small number incorporated seating, accessibility, or other public-space features, including the Hillsborough municipal site (RG07). These cases illustrate the potential for rain-gardens to support experiential and public-space functions, but such features were exceptions within the documented sample.

The lectures and manuals also emphasized the educational and demonstrative value of rain-gardens. Several school and library sites incorporated interpretive signage or were associated with volunteer planting and maintenance activities. In these cases, social value was expressed primarily through environmental education, public outreach, and awareness of stormwater-management practices rather than through recreation or community-space provision.

Aesthetic considerations recurred across interviews, field observations, and New Jersey-specific guidance materials, while the comparative documentary source provided a broader context for interpreting this theme. Interview participants and New Jersey professional materials highlighted the challenge of communicating the ecological purpose of rain-garden vegetation in settings where more manicured lawns and ornamental landscapes may be expected. The interviews revealed an especially clear tension between ecological planting and conventional expectations of landscape appearance. One municipal participant stated, “I want them to look nice, and I don’t necessarily know whether they are performing well at absorbing storm water and infiltrating it into the ground” (MU02). This statement illustrates how, for this municipal participant, visible landscape condition became an important practical indicator of success even when hydrological performance was not directly assessed. NGO participants described the same aesthetic tension from another perspective. One participant observed that some residents “think of [a] rain-garden as a messy wild garden,” while others value the meadow-like character of native planting (NG06). Another interview similarly reported that “People like them manicured. But then keeping them manicured is more demanding than the wild ones” (NG03). Considered together, the interviews suggest that visible maintenance and landscape appearance can become important dimensions through which rain-gardens are judged in practice.

Field observations likewise revealed substantial variation in the visual character of the documented sites, ranging from densely planted and deliberately composed gardens to sites characterized by sparse vegetation, extensive mulch or stone cover, bare areas, or limited evidence of maintenance. New Jersey guidance materials address this challenge through design and management approaches intended to communicate care and intentionality. Dunnett and Clayden (2007) place this issue within a broader landscape-design context, arguing that ecological and hydrological objectives alone may not ensure successful public landscapes if their appearance is perceived negatively. Their discussion similarly emphasizes the importance of legibility, design intention, and the relationship between ecological function and public acceptance. The convergence of the New Jersey evidence with this broader comparative perspective suggests that aesthetics is not simply an ornamental consideration, but an important dimension of public acceptance, stewardship, and long-term integration of rain-gardens into managed landscapes.

Interviewees indicated that public acceptance can be influenced by the appearance and maintenance of the landscape. Field observations documented considerable variation in visual appearance and upkeep, while participants described concerns about weeds, shade, odor, erosion, and perceived neglect. Conversely, participants used well-maintained examples to illustrate how visible care and landscape quality can support positive public responses. Because the study did not directly survey site users, these findings are interpreted as practitioner perceptions of public response rather than as measured public preferences.

The findings suggest that the documented rain-gardens provide localized greening and educational benefits, while their role within broader urban green-space networks remained limited among the cases examined. Recreational use and integration into broader urban green-space or ecological networks were uncommon in the field sample. Several cases, nevertheless, demonstrated that seating, accessibility, sensory planting, or deliberate landscape integration can expand public-space functions. Interview evidence similarly emphasized the predominantly small-scale stormwater-management orientation of rain-gardens, while NGO and watershed perspectives also highlighted opportunities for broader ecological, educational, and community benefits. Their capacity to function as major recreational or ecological assets at the city scale should therefore not be inferred from these site-scale installations. At the same time, long-term integration into managed landscapes depends partly on meeting expectations for visible care and landscape quality. Rain-gardens can therefore be understood as negotiated landscapes in which ecological objectives, technical functions, stewardship capacity, and cultural aesthetic expectations interact.

4.6. Climate Resilience, Scale, and the Limits of Parcel-Scale NbSs

Climate resilience emerged as a recurring theme in the New Jersey interviews, technical guidance, professional lectures, and regulatory material, although the emphasis and terminology varied among sources. Rain-gardens were consistently positioned as stormwater-management measures intended to promote infiltration, reduce localized runoff, improve stormwater quality, and, where site conditions permit, support groundwater recharge. More recent professional and regulatory materials increasingly situated these functions within broader concerns about climate resilience and adaptation, including increasing precipitation intensity, urban flooding, sea-level rise, climate-adjusted design storms, and community preparedness. Within this context, rain-gardens were presented as one component of broader green-infrastructure and watershed-management strategies rather than as stand-alone solutions to climate-related risks.

Dunnett and Clayden (2007) provide a broader comparative context for this interpretation by linking rainwater management and water-sensitive landscape design to climatic variability and changing patterns of water availability. Their treatment helps situate the New Jersey evidence within a wider development of landscape approaches that retain, infiltrate, and manage rainfall closer to where it falls. However, neither this comparative perspective nor the New Jersey evidence establishes that individual rain-gardens alone produce watershed-scale climate resilience. Rather, the evidence supports their role as localized interventions whose broader contribution depends on their distribution, cumulative implementation, maintenance, and integration with other stormwater and landscape strategies.

Interview participants also reflected on the role of rain-gardens in responding to climate-related uncertainty. From the watershed-steward perspective, rain-gardens are relatively manageable interventions that can address localized runoff and drainage concerns in already-developed urban areas, where larger hydrological interventions may be difficult to implement. The watershed stakeholder nevertheless distinguished this practical value from the larger scale of the hydrological problem, emphasizing the importance of rain-gardens being “strategically located as part of an overall plan” (ST01). Several participants also emphasized their educational and demonstrative value, viewing rain-gardens as visible interventions through which municipalities and communities can communicate stormwater-management practices and increase public awareness of climate-related challenges. From the watershed perspective, this public-facing role was particularly important: the stakeholder argued that their benefits extend beyond localized flood and pollutant reduction to “engaging the local community and teaching them about the importance of reducing impervious surfaces and managing water” (ST01). At the same time, some participants cautioned that the relative ease and visibility of rain-garden projects should not substitute for more complex interventions required to address watershed- and regional-scale problems. This tension between the practicality of localized action and the need for broader systemic intervention emerged as an important theme in the interviews.

Importantly, participants linked the possibility of expanding rain-garden implementation to the institutional capacity needed to sustain more installations. One NGO participant explained that “having the system in place for the constant maintenance and monitoring is a key to having more gardens” (NG06). Another NGO interview similarly emphasized that rain-gardens are “not one-time interventions” and require continuing maintenance, committed stewards, and resources for upkeep (NG02). Thus, increasing the number of installations also increases the long-term organizational obligations associated with them. These accounts suggest that scale is not solely a spatial issue; it is also an institutional and stewardship challenge.

Field observations documented site-level drainage conditions across the 18 sites. At many sites, no persistent ponding or obvious drainage problems were observed during the assessment, whereas other sites exhibited ponding, erosion, clogging, or other visible concerns (Table 2). These observations provided direct evidence of the physical condition of the rain-gardens at the time of the site visits and were considered alongside practitioner accounts and documentary descriptions. They were not treated as independent verification of claims regarding hydrological performance, which was not directly measured in this study. This distinction is important when considering scale: observed site conditions can characterize how individual installations were visibly functioning at the time of assessment, but they cannot establish their cumulative hydrological effect at the watershed scale.

Across New Jersey, evidence examined in this study revealed a recurring tension between the predominantly site- or parcel-scale implementation of rain-gardens and the watershed-scale nature of many of the environmental challenges they are intended to address. Interview evidence explicitly recognized this limitation. The watershed stakeholder characterized rain-gardens as “the low-hanging fruit of stormwater management mitigation measures” and cautioned that, although valuable, “they do not address watershed-scale issues or landscape-scale treatment” (ST01). This caution does not negate the value of distributed implementation; rather, it distinguishes between accumulating site-level interventions and undertaking watershed-scale planning. At the same time, other participants described efforts to organize distributed interventions within a broader watershed framework. Representatives of a statewide environmental association explained, “We work by watershed. We install as many rain-gardens as possible in each watershed” (NG03), describing a program in which multiple organizations implemented rain-gardens and other GI measures to support watershed water-quality objectives. Together, these perspectives reveal two complementary dimensions of scale: one concerns the strategic distribution of multiple small interventions across a watershed, while the other cautions that their accumulation should not itself be equated with watershed- or landscape-scale treatment. Broader contributions therefore depend not simply on multiplying individual rain-gardens, but on where they are located, how they are coordinated, and how they are integrated with complementary GI and watershed-management measures. The watershed interview extended this argument beyond hydrology. ST01 identified opportunities to amplify ecological benefits through watershed-scale strategies involving habitat connections, stream daylighting, increased urban green space, and integration with planning and zoning. This perspective suggests that the limitation is not necessarily the small physical size of rain-gardens, but their implementation as isolated projects without a larger spatial framework. In this sense, the potential contribution of rain-gardens to climate resilience and ecological objectives depends in part on whether site-level interventions are embedded in coordinated landscape and watershed strategies.

The combined interview and field evidence also indicates a fragmented pattern of implementation among the sites examined. Interview participants described implementation as dependent on individual property owners, institutions, municipal programs, partnerships, and easement opportunities, while field observations documented rain-gardens distributed across schools, libraries, municipal facilities, streetscapes, parking areas, and residential settings. The documented gardens generally appeared as individual or site-specific interventions rather than as physically connected components of larger ecological or open-space networks. Although individual sites may provide benefits within their immediate settings, coordinated landscape-scale connectivity was not evident among the sites examined in this study. This finding should not be interpreted as evidence that such coordination is absent elsewhere in New Jersey; rather, it characterizes the implementation pattern represented by the field sample and reinforces the scale issue identified in the interviews.

The scale critique developed here does not question the established role of rain-gardens as localized stormwater-management interventions. Rather, it concerns the relationship between the spatial scale of individual installations and the broader planning objectives to which they are increasingly connected. Climate resilience, watershed restoration, and ecological recovery operate at spatial scales considerably larger than individual rain-garden sites. The interviews, therefore, point toward a distinction between the effectiveness of individual rain-gardens for particular site-level functions and the planning required to translate distributed interventions into broader landscape and watershed objectives. Consequently, achieving broader ecological and climate-adaptation objectives requires that rain-gardens be understood as components of integrated GI, open-space, and watershed systems, alongside complementary interventions operating across multiple spatial scales.

4.7. Synthesis and Implications

Across the New Jersey interviews, field observations, professional lectures, technical guidance, and regulatory material, stormwater management consistently emerged as the principal rationale for rain-garden implementation. Infiltration, localized runoff management, stormwater quality improvement, and mitigation of site-level drainage problems were recurring objectives across these sources. Field observations documented the physical conditions of implemented rain-gardens, including sites without visible drainage problems and those exhibiting ponding, erosion, or other concerns. Dunnett and Clayden (2007) provided a broader comparative context for interpreting these findings within the development of multifunctional rain-garden and water-sensitive landscape approaches.

The study also demonstrates that rain-gardens depend on more than hydrological design. Across the evidence examined, long-term functioning was consistently linked to stewardship, maintenance, funding, institutional coordination, and public acceptance. Rain-gardens, therefore, function not only as engineered NbSs but also as socially and institutionally supported infrastructure. Participant accounts described these dependencies in terms of stewardship continuity, staffing expertise, funding, monitoring, and expectations regarding landscape appearance.

A recurring theme across the New Jersey evidence base was the tension between the scale of implementation and the scale of the environmental challenges being addressed. Rain-gardens are generally implemented at the site or parcel scale, whereas watershed degradation, habitat fragmentation, flooding, and climate-related risks operate across substantially larger spatial systems. At the same time, participants emphasized the educational and demonstrative value of rain-gardens as visible interventions through which residents, institutions, and municipalities can engage with stormwater and environmental issues. Some interview participants, however, cautioned that the visibility and relative feasibility of rain-garden projects could lead them to receive attention disproportionate to their capacity to address more complex regional and watershed-scale challenges. The findings, therefore, reveal a tension between the value of rain-gardens as accessible forms of local environmental action and the risk of treating such interventions as substitutes for broader systemic responses.

Field observations further indicated that many of the documented rain-gardens functioned as site-specific interventions with limited visible integration into larger open-space or recreational systems. Although signage at several sites communicated stormwater or ecological functions, the spatial configuration of many gardens did not appear to contribute substantially to broader park, streetscape, or recreational networks. Exceptions were also observed, including sites where seating, accessibility, sensory planting, or formal landscape integration expanded the garden’s role beyond stormwater management. These contrasts suggest opportunities to more deliberately integrate rain-gardens with green-space, recreational, ecological, and public-realm planning.

The findings suggest an opportunity to position rain-gardens more deliberately as components of broader GI systems rather than as stand-alone interventions. Their contribution may lie not only in localized stormwater management but also in their capacity to provide visible, adaptable, and replicable interventions that, when strategically coordinated with other measures, can support wider transitions toward more resilient urban landscapes.

5. Conclusion

This study examined how rain-gardens are conceptualized, implemented, governed, maintained, and situated within contemporary GI systems in New Jersey through stakeholder interviews, documentary analysis, and structured field documentation of 18 sites. By examining rain-gardens beyond their technical stormwater function, the findings address the three research questions through three interrelated dimensions: the translation of multifunctional GI ambitions into practice; the governance, institutional, and stewardship systems that sustain individual installations; and the relationship between site-scale implementation and broader watershed and climate-resilience objectives.

The findings show that rain-gardens are primarily operationalized as decentralized stormwater-management infrastructure. Infiltration, localized runoff management, stormwater-quality improvement, groundwater recharge where site conditions permit, and regulatory compliance consistently emerged as central objectives across the New Jersey evidence base. Ecological, educational, aesthetic, and climate-resilience benefits were also recognized, but generally remained complementary to the dominant hydrological rationale. Thus, while rain-gardens are conceptually associated with broader multifunctional GI ambitions, their operationalization in the cases examined remained principally hydrological, with ecological and social functions incorporated unevenly across sites and institutional settings. Field observations documented considerable variation in vegetation, maintenance, and visible site condition, illustrating differences in the post-installation condition of the sites examined.

A central contribution of the study is the conceptualization of stewardship as ‘invisible infrastructure.’ The evidence indicates that rain-gardens depend not only on soils, vegetation, and hydrological design but also on continuing human and institutional capacity. Maintenance responsibility, technical knowledge, funding, institutional coordination, and sustained stewardship were repeatedly identified as conditions supporting long-term functioning. Variation observed among the field sites, considered alongside practitioner accounts, reinforces the need to understand implementation as an ongoing institutional and stewardship process rather than a one-time design and construction intervention. Public-facing dimensions further shape this process through expectations of visible care, landscape quality, environmental education, and acceptance, although these findings reflect practitioner perspectives rather than directly measured public preferences. Together, these findings indicate that the long-term functioning of rain-gardens depends on the institutional and social systems that sustain them as much as on their physical design.

The findings also reveal an important scalar tension. Rain-gardens are predominantly implemented as individual site- or parcel-scale interventions, while watershed degradation, ecological connectivity, flooding, and climate resilience operate across much larger spatial systems. This does not diminish the value of localized interventions; rather, it distinguishes their site-level contributions from the broader outcomes attributed to GI. The evidence, therefore, supports only a conditional alignment between parcel-scale rain-garden implementation and broader watershed and climate-resilience ambitions. Increasing the number of rain-gardens alone should not be equated with watershed-scale transformation. Their broader contribution depends on where they are located, how they are coordinated, how they are maintained, and how they are integrated with complementary GI, open-space, and watershed-management strategies.

Rain-gardens should therefore be understood not as stand-alone solutions but as socio-ecological and institutional components of larger green infrastructure systems. Their broader value lies in combining localized stormwater management with ecological, educational, and public-facing opportunities while recognizing the institutional and spatial limits of individual interventions. Future research should examine how distributed networks of rain-gardens can be strategically coordinated across watersheds and evaluate their cumulative hydrological, ecological, and social outcomes through longitudinal and multi-scale assessment.