Final Report: Alternative Urbanization Scenarios for an Agricultural Watershed: Design Criteria, Social Constraints, and Effects on Groundwater and Surface Water Systems

EPA Grant Number: R828010
Title: Alternative Urbanization Scenarios for an Agricultural Watershed: Design Criteria, Social Constraints, and Effects on Groundwater and Surface Water Systems
Investigators: Lathrop, Richard C. , LaGro Jr., James A. , Nelsoni, Edward B. , Zedler, Joy B. , Bahr, Jean M. , Bradbury, Kenneth R. , Greb, Steven R. , Potter, Kenneth W. , Nowak, Peter
Institution: University of Wisconsin Madison , Wisconsin Department of Natural Resources
EPA Project Officer: Packard, Benjamin H
Project Period: January 15, 2000 through January 14, 2003
Project Amount: $886,105
RFA: Water and Watersheds (1999) RFA Text |  Recipients Lists
Research Category: Water and Watersheds , Water


This research project focused on mitigating the impacts of urbanization in agricultural regions in which both humans and aquatic ecosystems greatly depend on groundwater. The goal was to fill critical knowledge gaps and extend/develop analytical and modeling tools to minimize hydrologic impacts of urbanization. We have considered the full range of relevant water issues, including storm runoff, groundwater depletion, wastewater treatment, eutrophication, and wetland degradation. We also have addressed the interaction among these issues and the social and political opportunities for, and constraints on, effective management. In this report, we highlight six research objectives utilizing a comprehensive case study that evaluated the benefits of alternative management practices at the watershed scale.

The objectives of this research project were to: (1) evaluate alternative management practices and patterns of urbanization by considering a range of urban development issues, including storm runoff, groundwater depletion, wastewater treatment, wetland degradation, thermal pollution, and eutrophication; (2) fill critical knowledge gaps and extend (or develop) analytical and modeling tools that will minimize the hydrologic and ecological impacts of urbanization; (3) construct comparable land use/water management scenarios for a test watershed (Pheasant Branch), including "low-impact development" designs, and evaluate their approximate economic costs, social/political acceptability, and hydrologic and ecological impacts; (4) examine urban impacts on wetlands, especially their biodiversity, and determine which native species can thrive in constructed urban bioretention wetlands or rain gardens; (5) evaluate farmer behaviors needed to reduce high soil P concentrations in agricultural lands that are likely to be converted to urban development; and (6) evaluate the social and institutional barriers to low-impact development and provide guidance to local governments and citizen groups for improving the management and protection of critical aquatic resources in rapidly urbanizing landscapes.

Much of the research was conducted as a case study in the North Fork of the Pheasant Branch subwatershed in the western basin of the Lake Mendota watershed near Madison, Wisconsin. The current land use in the Pheasant Branch subwatershed is largely agricultural, although urban expansion into the watershed is imminent. The watershed contains or influences several critical aquatic systems, including a large spring complex, wetlands, and Lake Mendota-the most significant lake in the county.

Summary/Accomplishments (Outputs/Outcomes):

Hydrogeologic Research

Optimal Well Siting and Operation. A major goal of this component of the research was the development of a numerical model of groundwater flow with which effects of municipal pumping, as well as enhanced infiltration practices, could be quantitatively evaluated. Although an existing, county-scale numerical model had been previously developed, it was at a scale that was too coarse to simulate many of the springs and wetland areas of concern. In addition, the existing model generated a poor match to observed baseflow in many streams. Development of a refined model first required an improved understanding of the sources of water to major springs.

Initial conceptual models of spring flow were tested through field and modeling studies in the nearby Nine Springs Creek watershed. Geochemical analyses of springs and water from boreholes in that watershed indicated a bedrock rather than glacial sediment source for the springs (Swanson, et al., 2001). Borehole testing in two existing wells and a nested pair of newly drilled bedrock wells revealed the discrete high permeability zones in one of the shallow bedrock units. Analytical and numerical modeling (Swanson and Bahr, 2004) demonstrated that the steady spring flow observed in the Nine Springs Creek watershed could be supported by preferential flow through thin zones in shallow bedrock.

Building on the initial conceptual model developed for the Nine Springs Creek watershed, additional bedrock wells were drilled near the major springs in our case study watershed (Pheasant Branch) and in the Token Creek watershed (eastern part of the larger Lake Mendota watershed). Interval packer tests in these wells revealed similar high-permeability zones in the shallow bedrock. The correlation over tens of kilometers between bedrock high permeability zones in these three watersheds is discussed in Swanson et al. (in review). Recognition of the potential for sandstone aquifers to contain such continuous preferential flow zones has important implications for managing groundwater resources and protecting water supplies from sources of contaminants.

The test bedrock well in the Pheasant Branch subwatershed also provided stratigraphic information that confirmed the presence of a regional aquitard (shale layer) separating the upper and lower bedrock aquifers. The effects of pumping by nearby municipal and other high capacity wells on water levels in the upper and lower bedrock aquifers were evaluated by examining continuous water level records from two zones of the test well separated using an inflatable packer. Comparison of the water-level data to records of precipitation and pumping rates for nearby deep-aquifer wells revealed that pumping causes frequent cycling of water levels in the lower aquifer, whereas the upper aquifer has relatively steady water levels that respond primarily to precipitation. These results illustrate the effectiveness of the regional shale aquitard in isolating the lower bedrock aquifer and also confirm the hypothesis that steady spring flow rates are maintained by water discharging from the shallow bedrock.

A telescoped model of the Pheasant Branch watershed was then developed, incorporating a high permeability layer in the upper bedrock to simulate the effects of preferential bedrock flow zones. This model provided an improved calibration to spatial variations in groundwater discharge to streams and at springs. The model was used to simulate potential effects of urban expansion and increased groundwater pumping. Simulations of increased groundwater withdrawal based on projected demand for the year 2020 resulted in relatively modest decreases in base flow of up to 12 percent in Pheasant Branch. Simulations with wells pumping from the lower aquifer showed decreases of less than 1 percent in spring flow, a result that was independent of the locations of the wells being pumped. Decreases of approximately 7 percent in groundwater discharge to wetlands, however, were found for simulations including either deep or shallow wells near the Pheasant Branch marsh wetland system. More significant impacts were simulated for scenarios incorporating decreases in recharge that would accompany increased impervious area from urban development: baseflow decreases up to 63 percent along Pheasant Branch and 22 percent at Pheasant Branch marsh. These results indicate the need for maintaining or enhancing local recharge in order to limit negative impacts on groundwater-fed aquatic ecosystems in this setting.

Water Quality Impacts of Unsewered Subdivisions. From the perspective of water quantity, subdivisions with on-site wastewater disposal (septic) systems have the advantage that water is returned to the aquifer locally instead of piped to a distant treatment plant for possible export to another watershed. Such septic systems, however, also serve as a source of contaminants that can be released to shallow groundwater. In urbanizing areas where the previous land use is agricultural, the contaminant sources associated with unsewered subdivisions replace former agricultural sources. This complicates the problem of quantifying the contaminant loading from unsewered subdivisions because measured contaminant concentrations may be from either current septic sources or remnants of past land use practices.

Our project, with additional funding from the State of Wisconsin, initiated a long-term monitoring program at a new unsewered subdivision that is currently being developed. Data from this study will allow quantification of contaminant loading both for conventional and novel septic technologies through a direct comparison of water quality prior to and following conversion of agricultural land to an unsewered residential community. A monitoring network of 19 wells installed prior to construction of any homes provided more than a year of data with which to evaluate spatial and temporal variations in background concentrations of nitrate and other constituents. Temporal variations in nitrate and chloride are large. For example, both nitrate and chloride concentrations in the wells decreased during the spring recharge period, whereas earlier in the spring, chloride concentrations in some of the wells increased as a result of infiltration of water containing road salt. As discussed in Wilcox, et al. (in revision for Ground Water), these variations can be explained by seasonal variations in recharge, local loading patterns, aquifer heterogeneities, and surface topography, all of which must be adequately characterized for a given site to distinguish between urbanization and agriculture sources of groundwater contaminants.

Hydrogeologic Controls on Wetland Biodiversity. Assessing the impact of urban disturbances on wetland biodiversity and designing effective restoration strategies requires adequate understanding of the controls on biodiversity in undisturbed wetlands. Among important controls are hydrogeologic and geochemical conditions. As part of our project, we conducted a detailed study of a relatively undisturbed wetland in which sharp transitions of plant communities from fen to sedge meadow and shallow marsh occurred with minimal topographic relief. Subsurface coring revealed a heterogeneous stratigraphy of peat and glacial deposits. The location and thickness of a buried silt loam layer correlated with the locations of vegetation transitions. Major ion and stable isotope signatures of water from shallow wells also vary across the site as a function of the degree of mixing between discharging regional groundwater and local precipitation.

The subsurface stratigraphy controls the rate of groundwater discharge, which in turn affects water chemistry. The marsh vegetation is adapted to frequent and long duration inundation that occurs because of limited infiltration through the silt during high water levels. Cattails, the dominant species in the marsh, are tolerant of a range of chemical conditions. In contrast, vegetation in the fen and sedge meadow is more sensitive to hydroperiods and variations in water chemistry. The results of this work have important implications for attempts at wetland creation to substitute for wetlands that might be degraded or lost during urban development. Because hydroperiods and water chemistry can be largely controlled by subsurface stratigraphy, creating the proper conditions to establish sensitive vegetation communities may be precluded in the absence of subsurface conditions that allow steady groundwater discharge. This implies that careful management of remaining fen and sedge meadows is critical to preserving the functions they perform.

Impacts of Altered Hydrologic Conditions on Wetland Biodiversity

The spread of invasive plants into natural and restored habitats is a ubiquitous global problem and one of the greatest threats to biodiversity (Zedler and Kercher, 2004). Although many invaders spread rapidly, the causes of their expansion are rarely tested and reasons why some proceed to form monotypes (displacing all native species) are unexplored. In the midwestern United States, monotypes of reed canary grass [Phalaris arundinacea L.] develop in wetlands that receive chronic inflows of runoff from agriculture activities and urban development. Over 40,000 ha of Wisconsin wetlands are now dominated by this species (Bernthal and Willis, 2004).

Field studies. Once invaded by Phalaris, wet meadows retain few species. In our field sampling, we found up to 60 species in little-disturbed reference sedge meadows (Kercher, et al., 2004). In sedge meadows that had indicators of hydrological disturbance (culverts, drainage ditches, sediment plumes), however, we found up to 15 fewer species than in nearby undisturbed areas. Furthermore, the species lost tended to be the more rare, specialized species that Wisconsin botanists have classified as "high quality." (Kercher, 2003) Our field sampling procedures were tested in detail, resulting in a publication that compared methods (Kercher, et al., 2003).

Mesocosm experiment. We uncovered the mechanisms by which this widespread invasive clonal grass spreads and forms a monotype by comparing the responses of 17 taxa to 4 hydroperiods (Kercher and Zedler, in press) and by testing the effects of components of runoff (excess water, nutrients, and sediments, alone and in combination) on Phalaris seedlings introduced to wet prairie vegetation in 140 replicate 1.1-m2 mesocosms (Kercher, 2003; Kercher and Zedler, 2004). In pot microcosms, Phalaris and another invasive plant (hybrid Typha x glauca) outperformed all native taxa in all hydroperiods. In the mesocosms planted to native species, the invasion process was reenacted as some treatments shifted the diverse wet prairie to a near-monotype of Phalaris in just two growing seasons. Two mechanisms explained the conversion: (1) loss of natives as a result of prolonged flooding and sedimentation; and (2) superior growth of Phalaris with prolonged flooding, nutrient additions, and sediment additions interacting to increase the invader's biomass (Kercher and Zedler, 2004).

Our mesocosm study is unique in documenting significant interactions among disturbance factors on invasion by Phalaris. Phalaris biomass showed significant interactions for nutrient x flood regime and sediment x flood regime in Year 2. The addition of sediments or nutrients combined with early season or constant flooding amplified invasion 30-130 percent above expected (additive) levels.

Other results of our wetland research component have a more direct linkage to our social research component on the property owner acceptance of rain gardens to increase infiltration. In our outdoor mesocosm experiments, we identified four native plant species that are likely to grow well in bioretention areas, including rain gardens because of their rapid biomass production and their ability to tolerate periods of both flooding and dryness: Carex stricta, Calamagrostis Canadensis, Spartina pectinata, and Eupatorium perfoliatium. We also identified other species that were least suitable for rain gardens because of slow growth and inability to tolerate flooding.

Conceptual Model. We developed a conceptual model that indicates how nutrient-rich runoff from either urban or rural landscapes accelerates invasibility at the landscape scale. Because wetlands function as landscape sinks, they are vulnerable to influxes that create opportunities for invasion. When flooding brings opportunist species to the low-lying sites, invasive species take advantage of the opportunities to establish new plants. Then, ample nutrients and moisture accelerate growth of the established invaders. Given continued influxes of water and nutrients, aggressive invaders crowd out natives and form monotypes (Zedler and Kercher, 2004). At the micro-scale, the influx of water and sediment alters the sedge meadow wetland system and the tussocks that support other plant species. Infilling between the tussocks eliminate microtopography and provides a nutrient-rich substrate with little light limitation. Hence, colonization and dominance by reed canary grass can occur rapidly.

Summary. Our key ecological study component is linked to the physical attributes of our area's hydrologic system. To maintain the ecological health and biodiversity of natural wetland systems throughout the region, natural infiltration rates without an increase in runoff and associated nutrients and sediments must be maintained as an area urbanizes. Complex synergistic effects suggest that simple reductions in fertilizer use, flooding, or sedimentation alone will not suffice to protect wetlands from being overtaken by Phalaris. We suggest a holistic approach to controlling this invasive plant, including: (1) minimizing runoff from agricultural fields and urban hardscapes (using depressions, swales, and other infiltration-enhancing measures); (2) removal of Phalaris (likely requiring herbicide and/or removal of sod); (3) replanting of natives; (4) long-term surveillance and spot-treating of reinvading clones; and (5) reintroducing native species that do not recover on their own. A long-term commitment will be required to restore biodiversity to wetlands degraded by Phalaris.

Thermal Impacts of Urban BMPs

Increased water temperature is an often overlooked water quality concern for urban best management practices (BMPs). This subproject examined three urban BMPs (0.43-ha wet detention pond, 0.10-ha bioengineered wetland, 26-m long grass swale) and quantified their impact on the thermal regime of runoff water. Water temperature and flow at the inlet and outlet of each BMP were monitored during four to five summer runoff events. Using these data, heat budgets were developed for each event with heat change calculated relative to rainfall (air) temperature.

Of the three BMPs, the wet pond contributed the greatest amount of additional heat to the water, resulting in an average volume-weighted heat increase of 20 percent. This heat was from previously stored water that was displaced during a subsequent storm. The wetland complex increased the heat output of runoff water by an average of 10 percent. The smaller heat increase of the wetland was because of its smaller water storage capacity with less heat retained than in the pond. In contrast, runoff water passing over the grass swale actually lost heat (-43%). This loss was a result of water lost through infiltration and the complement of heat it contained, especially for the first flush of water off of hot impervious surfaces before they are cooled. Thus, innovative practices, such as grass swales and rain gardens, that infiltrate water can reduce thermal pollution from urban watersheds when compared to traditional stormwater practices, such as detention ponds, where thermal loading to receiving waters can be particularly significant.

Hydrologic Modeling

The overall goal of this project was to fill critical knowledge gaps and extend (or develop) analytical and modeling tools to minimize hydrologic impacts of urbanization. With respect to stormwater management, the primary emphasis was on small-scale infiltration practices, such as bioretention facilities and infiltration trenches. Except when soils or subsoils are impermeable, these practices can be used in urbanizing areas to prevent increases in the volume of storm runoff and decreases in the volume of groundwater recharge (Potter, 2004). In this component of the research, we developed numerical models that could be used to design and evaluate the benefits of small-scale infiltration practices. The models were developed for use at three spatial scales: individual practice, development, and watershed. These models were then applied to provide insights about the design and use of small-scale infiltration practices.

Individual Infiltration Practices. We developed two models for simulating the performance of a multi-layered infiltration practice in continuous time. The first model uses the one-dimensional Richard's Equation to simulate flow through the infiltration practice. Application of this model to a three-layered bioretention facility demonstrated three important points. First, if the purpose of the facility is to increase groundwater recharge, there is an optimal facility size. For the climate of southern Wisconsin, the optimal size is about 15 percent of the contributing impervious area. Second, an optimally designed bioretention facility can yield groundwater recharge rates well above rates that occur in undeveloped conditions. For example, an optimally designed bioretention facility in southern Wisconsin can more than double undeveloped recharge rates. This increase in recharge is because of the focusing of infiltration, which reduces losses to evapotranspiration. Third, an infiltration facility that is designed to maximize groundwater recharge can significantly reduce runoff volumes. These results are published in Dussaillant, et al. (2003).

The long run times of our Richard's Equation model make it unsuitable for use in design. Hence, we developed a much faster model based on the Green-Ampt equation. This model incorporates a user-friendly interface and allows the user to evaluate the performance of a multi-layered infiltration practice with an underdrain. We have also incorporated an algorithm that determines the facility size required to ensure a specified volume of stormwater retention ("stayon"). This algorithm is being used by the State of Wisconsin to implement its new stormwater rules. We also are near completion of a technical manual for use in designing bioretention facilities.

Development Scale. We also recognized the need for a modeling approach for estimating the benefits of infiltration practices at the development scale. To meet this need we developed a spreadsheet model based on the commonly used Natural Resources Conservation Service's "curve number" method, augmented to account for infiltration practices. We used our spreadsheet model to assess the potential benefits of infiltration practices in the context of four alternative development types: conventional curvilinear, urban cluster, coving, and new urbanism. Model results, published in Brander, et al. (2004), indicate that urban cluster developments produce the smallest volume of runoff because of the large portion of land kept in a natural condition, and that significant reductions in runoff can be achieved in all four development types if infiltration practices are used to treat many impervious surfaces.

Watershed Scale. To model infiltration practices at the watershed scale, we modified the U.S. Geological Survey's Precipitation Modeling System (PRMS). PRMS is a modular design, distributed-parameter, continuous rainfall-runoff model. Modifications included changing the model to allow for water to be directed from impervious areas to infiltration practices and modifying the infiltration algorithm to include ponding.

We applied the modified model to the North Fork of the Pheasant Branch watershed, a 50-km2 watershed in southern Wisconsin that had been previously modeled by Steuer and Hunt (2001) for existing conditions and two hypothetical urbanization scenarios. We considered two levels of infiltration practices, one moderate and one high. The results indicate that intensive use of infiltration practices can preserve groundwater recharge rates under either development scenario but can only preserve runoff volumes for the moderate development scenario.

Agricultural Nutrient Management at the Urban Fringe

Our work was conducted in the "urban fringe" of the Pheasant Branch watershed near Middleton, Wisconsin. In this area, farming operations compete for land with development pressures while continuing to increase the soil P levels on their fields. These operations find themselves facing the two equally unattractive propositions of paying for manure to be hauled elsewhere or over-applying manure to the point that hydrologically vulnerable and erosive fields become saturated with P. We observe that the latter is the more frequent choice.

In the first phase of our research, we set out to sample soils for the purpose of determining where soil P surpluses had accumulated. We obtained cooperation of animal feeding operations (AFOs) in the 2,500 ha North Fork subwatershed of Pheasant Branch. These operations amounted to an area of approximately 1,300 ha at a sampling density of approximately one sample per ha on over 220 fields. Samples were analyzed for P using an agronomic test recommended for Wisconsin soils (Bray-P1). Our findings indicate soil P surpluses had accumulated at "sub-field" and field scales. In the case of a few operations, the majority of fields managed were saturated with excessive soil P levels.

The next phase consisted of interviewing the dairy producers who managed these fields to understand if management decisions had resulted in the soil P surpluses. Patterns of responses within the interviews were examined for decisions being made at the sub-field (operational), field (tactical), and farm (strategic) levels of farm management defined by Bouma, et al. (1997) and Beegle, et al. (2000).

In regards to sub-field decisions, it was evident that a great deal of variability existed, indicating producers found it very hard to make precise management decisions. The most noteworthy point they made was the clear preference to haul only full loads of manure to their fields, thus leading to over-application of manure to portions of their fields.

At the field level of management, the first and most prevalent example of this is related to the tenure relationships of the producers to the fields under their management. It was common for most of the producers interviewed to develop informal and formal arrangements with other producers and local area landowners to rent land for crop production. Many of these rented parcels, however, were not available to producers from season to season because of unstable rental arrangements brought on by competition with developers for rented parcels. This resulted in a dynamic land base that expanded or contracted annually. The ratio of owned-to-operated land was rather large for the small and mid-sized producers (> 0.75) but was much smaller for the larger operations (< 0.50). This limitation made some producers reluctant to develop and implement a nutrient management plan.

Finally, we examined the constraints faced by AFOs that manage manure in an urbanizing setting by sending a structured questionnaire to 186 farmers in a 212-km2 area within the Lake Mendota watershed. The urbanizing setting was found to pose specific constraints on decisions at the farm level of management. For instance, producers cited that urbanization pressures had resulted in a fragmented pattern of land ownership and rental. This urbanizing context caused greater field separation and resulted in the need to haul manure greater distances on local roads (Cabot, et al., 2004). The results of the survey indicated that producers were significantly more likely to encounter several situations (e.g., weekend traffic on local roads, complaints about spilled manure on public roads, springtime weight restrictions on local roads, traffic passing the hauler under unsafe conditions) as problematic if they were placing manure on fields located near home residences. In non-urbanizing watersheds, these problems do not constrain their decisionmaking in regards to manure management. Because of traffic problems in an urbanizing setting, the likelihood increased for producers to repeatedly place manure on closer fields, which in turn can result in P surpluses.

Management Implications. A popular strategy for helping dairy and livestock producers manage manure to meet agronomic and environmental goals in land-constrained areas and on fields where P surpluses have developed is to encourage cooperative agreements between producers and cash-grain farmers. Although cash-grain farmers have some concerns about receiving manure, when possible these agreements can alleviate nutrient surpluses that develop on land where manure is over-applied. An urbanizing setting presents a problem for the feasibility of these arrangements. Within the maximum distance that producers can profitably haul manure, tracts of cash grain land tend to be sparse already. When producers compete for these tracts with developers, their situation becomes even more constrained. Another strategy that could be useful in helping AFOs manage manure within a dwindling land base is to encourage manure brokering programs that direct manure to lands that can accept them. Finally, precision conservation (Berry, et al., 2003) also may make it possible for producers to manage manure and nutrients at scales closer to the ones at which nonpoint source pollution originates. The hope of precision conservation is that producers will use geographic positioning systems (GPS) mounted to their equipment to avoid applying manure to hydrologically active zones or areas of elevated soil P accumulation. Precision conservation, however, is fairly costly and unfamiliar to most producers. Our current research efforts are aimed at making this technology more accessible.

Social Research Impediments to Low Impact Development

Two areas of our social research relate directly to the barriers or impediments that must be overcome if low-impact development is to be adopted as the norm in urban design. The first set of barriers can be classified as institutional, such as municipal ordinances that restrict any new development to environmentally unfriendly standard practices. The second set of barriers can be generally grouped in the realm of human biases and/or inadequate knowledge by key players. Each set of barriers were assessed separately as part of our project's research goals.

Institutional Barriers. Land development patterns on the urban fringe are strongly influenced by local subdivision and zoning ordinances. Zoning regulations are established to control the use of property, whereas subdivision regulations address site planning and design. Subdivision ordinances are critical tools for guiding and influencing development attributes such as lot size, building setbacks, street configuration, and street width.

Often, a subdivision ordinance is a rural community's only tool available to influence its physical development and mitigate potentially harmful land development impacts. Subdivision regulations have the most influence on development patterns at the site scale because they establish the procedures and standards that one must follow when dividing a large parcel of land in preparation for development.

Dane County (the location of our research study) was the fastest growing county in Wisconsin between 1990 and 2000, with the population increasing from 367,085 to 426,526 (U.S. Census, 2000). Approximately 25,500 building permits were issued in the county between 1990 and 2000. About one-half of the permits were for multi-family dwelling units and one-half for single-family dwelling units (U.S. Census, 2000). In recent years, more single-family dwellings have been constructed in the outlying urban service areas. In addition, the average size of new housing units has also increased (Dane County Regional Planning Commission, 2001).

Dane County has 60 minor civil divisions (towns, villages, and small cities exclusive of Madison). To assess the local regulatory standards for land development, we conducted a content analysis of all 60 subdivision ordinances. Also, a random 20 percent sample of subdivision plats was taken from each of the minor civil divisions with more than five subdivisions platted during the 1990s. This yielded a sample of 75 subdivisions for assessing current practices.

Our study found that 97 percent of sampled subdivisions in Dane County were "conventional" subdivisions, which are characterized by large lots, wide streets, curbs and gutters, and detention basins. Only 3 percent were "Traditional Neighborhood Developments" or "conservation" subdivisions, which are characterized by clustered small lots, narrow streets, and common open spaces. The average area of each subdivision was 32 acres (12.6 ha) with an average of 48.6 lots in each subdivision. There was very little evidence of BMPs to ensure low-impact residential development. The vast majority of the subdivisions included large, connected impervious surfaces (e.g., streets with required curbs and gutters, cul de sacs with a required pavement diameter of 110 feet) that reduce stormwater infiltration and increase runoff. Most of the subdivisions also utilized a "pipe and pond" approach to stormwater management, further diminishing on-site infiltration and recharge. In summary, Dane County's subdivision regulations generally encouraged, and in some instances mandated, "high-impact" development practices.

Barriers From Human Biases or Inadequate Knowledge. Many of the environmentally unfriendly ordinances discussed above embody the interests and views of various institutional players (e.g., fire department and snow removal personnel). Their reluctance to change reflects the deeper problem that municipal officials (e.g., planners, engineers) and citizen oversight committees, in general, have little experience with low-impact development designs pertaining to water management.

In-depth personal interviews conducted with a wide range of individuals (e.g., municipal officials, regional planners, builders, developers, engineers, and environmental consultants) instrumental in the adoption of alternative storm water management practices further elucidated this problem. These interviews disclosed that the adoption of even a single, simple practice such as a rain garden is a potentially complex event. A large number of actors and considerations are important including cost; the physical, institutional and legal environments; and the understanding of various key actors (engineers, builders, developers). Interestingly, homeowners and renters are of scant importance in driving the decision to install these practices in new developments. Decisions on these matters are made early in the development phase when owners/tenants have little input or impact.

Another finding of our sociological research is a key barrier to the adoption of infiltration practices: the lack of knowledge about the practices and their effectiveness under different conditions. Conventional storm water management practices are well understood; their alternatives are not. Builders, developers, planners, regulators, and municipal officials need to know how these practices can be installed, how well they function in different settings, and what they cost to install and maintain. Additional research and documentation of the practices can overcome this barrier. In particular, a high priority to funding and implementing demonstration projects of the low impact practices in a variety of settings is critical to their rapid acceptance.

Impediments for Retrofitting Existing Urban Areas. Although the previous discussion addresses issues related to implementing low-impact development practices in areas undergoing urbanization, different problems exist for retrofitting these practices in established urban areas. Other than larger scale infiltration systems installed on public lands, individual homeowners and commercial property owners are the key players for implementing rain gardens or other infiltration systems at the scale of individual properties.

Through the use of focus group listening sessions conducted in May 2002, we were able to document how residents of Maplewood, Minnesota, accepted the voluntary installation of rain gardens as part of larger municipal projects to alleviate chronic flooding problems in their community. In general, homeowner "gardeners" tended to be younger, generally liked gardening, and often had experienced water problems on their property as compared to "non-gardeners." Voluntary sign-up brought a greater sense of buy-in and prevented unwilling homeowners from having to plant and maintain gardens that were perceived as requiring too much care. Participants found the ideas of "helping your neighbor" and getting rid of standing water that was disproportionately affecting some in their neighborhood as more persuasive reasons for participating than broader appeals for beautifying the community and saving taxpayer costs for managing stormwater in the larger watershed. Because few homeowners had any prior knowledge of rain gardens, they had not developed specific attitudes toward rain gardens other than the word "garden" has the connotation of "work." The common mode of reasoning against having a rain garden-"I don't have a water problem, so I don't need a garden"-must be overcome by educational programs. The value of well-organized rain garden demonstration projects is paramount to the infiltration practice's successful implementation by enough homeowners to make a difference in the watershed management of a community.

Policy Implications for Urbanizing Areas. The Wisconsin Smart Growth Law requires all communities that want to make a land use decision to create and adopt a comprehensive plan by January 2010. The Smart Growth legislation also required all communities with a population of 12,500 or more to develop a Traditional Neighborhood Development ordinance by January 2002. Traditional Neighborhood Development ordinances encourage development of compact, transit oriented, pedestrian friendly, mixed-use, and sustainable neighborhoods. To reduce land development impacts, local subdivision ordinances should be examined, and revised if necessary. These ordinances should be consistent with the principles of smart growth. And they should promote, if not require, low-impact development practices. Our project has identified ordinances that are barriers to low-impact development and will be making recommendations to eliminate this set of barriers.

Journal Articles on this Report : 18 Displayed | Download in RIS Format

Other project views: All 72 publications 19 publications in selected types All 18 journal articles
Type Citation Project Document Sources
Journal Article Brander KE, Owen KE, Potter KW. Modeled impacts of development type on runoff volume and infiltration performance. Journal of the American Water Resources Association 2004;40(4):961-969. R828010 (Final)
  • Abstract: Wiley Online
  • Journal Article Cabot PE, Bowen SK, Nowak PJ. Manure management in urbanizing settings. Journal of Soil and Water Conservation 2004;59(6):235-243. R828010 (Final)
  • Abstract: Journal of Soil and Water Conservation
  • Journal Article Cabot PE, Nowak P. Planned versus actual outcomes as a result of animal feeding operation decisions for managing phosphorus. Journal of Environmental Quality 2005;34(3):761-773. R828010 (Final)
    R830669 (2003)
    R830669 (2004)
    R830669 (2005)
    R830669 (Final)
  • Abstract from PubMed
  • Full-text: American Society of Agronomy-Full Text HTML
  • Abstract: American Society of Agronomy
  • Other: American Society of Agronomy-PDF
  • Journal Article Dussaillant AR, Wu CH, Potter KW. Richards equation model of a rain garden. Journal of Hydrologic Engineering 2004;9(3):219-225. R828010 (Final)
  • Abstract: ASCE
  • Journal Article Kercher SM, Frieswyk CB, Zedler JB. Effects of sampling teams and estimation methods on the assessment of plant cover. Journal of Vegetation Science 2003;14(6):899-906. R828010 (Final)
    R828675 (Final)
    R828675C002 (2002)
    R828675C002 (2003)
    R828675C002 (2004)
    R828675C002 (Final)
  • Full-text: University of Wisconsin - Full Text PDF
  • Abstract: Wiley Online-Abstract
  • Journal Article Kercher SM, Zedler JB. Multiple disturbances accelerate invasion of reed canary grass (Phalaris arundinacea L.) in a mesocosm study. Oecologia 2004;138(3):455-464. R828010 (Final)
  • Full-text: SpringerLink - Full Text HTML
  • Abstract: SpringerLink
  • Other: SpringerLink - Full Text PDF
  • Journal Article Kercher SM, Zedler JB. Flood tolerance in wetland angiosperms: a comparison of invasive and noninvasive species. Aquatic Botany 2004;80(2):89-102. R828010 (Final)
  • Full-text: University of Wisconsin - Full Text PDF
  • Abstract: ScienceDirect
  • Other: ScienceDirect - Full Text HTML
  • Journal Article Kercher SM, Carpenter QJ, Zedler JB. Interrelationships of hydrologic disturbance, reed canary grass (Phalaris arundinacea L.), and native plants in Wisconsin wet meadows. Natural Areas Journal 2004;24(4):316-325. R828010 (Final)
  • Full-text: University of Wisconsin - Full Text PDF
  • Abstract: Natural Areas Association
  • Journal Article Maurer DA, Zedler JB. Differential invasion of a wetland grass explained by tests of nutrients and light availability on establishment and clonal growth. Oecologia 2002;131(2):279-288. R828010 (Final)
  • Full-text: SpringerLink - Full Text PDF
  • Abstract: SpringerLink
  • Other: University of Wisconsin - Full Text PDF
  • Journal Article Maurer DA, Lindig-Cisneros R, Werner KJ, Kercher S, Miller R, Zedler JB. The replacement of wetland vegetation by reed canarygrass (Phalaris arundinacea). Ecological Restoration 2003;21(2):116-119. R828010 (Final)
  • Abstract: EBSCO Host Connection
  • Other: Ecological Restoration - citation
  • Journal Article Nowak PJ, Cabot PE. The human dimension of resource management programs. Journal of Soil and Water Conservation 2004;59(6):128A-135A. R828010 (Final)
  • Full-text: University of Wisconsin-Extension - Full Text PDF
  • Abstract: Journal of Soil and Water Conservation
  • Journal Article Nowak P, Bowen S, Cabot PE. Disproportionality as a framework for linking social and biophysical systems. Society and Natural Resources: An International Journal 2006;19(2):153-173. R828010 (Final)
  • Full-text: University of Wisconsin-PDF
  • Abstract: Taylor & Francis Online-Abstract
  • Journal Article Potter KW. Managing stormwater at the source. Transactions, Wisconsin Academy of Sciences, Arts, and Letters 2004;90:67-73. R828010 (Final)
    not available
    Journal Article Swanson SK, Bahr JM, Schwar MT, Potter KW. Two-way cluster analysis of geochemical data to constrain spring source waters. Chemical Geology 2001;179(1-4):73-91. R828010 (Final)
  • Full-text: ScienceDirect - Full Text HTML
  • Abstract: ScienceDirect
  • Other: ScienceDirect - Full Text PDF
  • Journal Article Swanson SK, Bahr JM. Analytical and numerical models to explain steady rates of spring flow. Ground Water 2004;42(5):747-759. R828010 (Final)
  • Abstract from PubMed
  • Full-text: National Ground Water Association - Full Text PDF
  • Abstract: Wiley Online
  • Journal Article Swanson SK, Bahr JM, Bradbury KR, Anderson KM. Evidence for preferential flow through sandstone aquifers in Southern Wisconsin. Journal of Sedimentary Geology 2006;184(3-4):331-342. R828010 (Final)
  • Abstract: ScienceDirect
  • Journal Article Wilcox JD, Bradbury KR, Thomas CL, Bahr JM. Assessing background ground water chemistry beneath a new unsewered subdivision. Ground Water 2005;43(6):787-795. R828010 (Final)
  • Abstract from PubMed
  • Abstract: Wiley Online
  • Journal Article Zedler JB, Kercher S. Causes and consequences of invasive plants in wetlands: opportunities, opportunists, and outcomes. Critical Reviews In Plant Sciences 2004;23(5):431-452. R828010 (Final)
  • Full-text: Global Restoration Network - Full Text PDF
  • Abstract: Taylor Francis Online
  • Supplemental Keywords:

    ecosystem protection, hydrology, nutrients, watersheds, wet weather flows, agricultural watershed, aquatic biota, aquatic degradation, biodiversity, contaminated sediment, ecological impacts, eutrophication, groundwater, irrigation, nutrient cycling, phosphorous, runoff, urban development, water quality,, RFA, Scientific Discipline, Geographic Area, Water, Ecosystem Protection/Environmental Exposure & Risk, Water & Watershed, Nutrients, Ecosystem/Assessment/Indicators, Environmental Chemistry, State, Wet Weather Flows, Ecological Risk Assessment, Environmental Engineering, Watersheds, ecological effects, environmental monitoring, fate and transport, urbanization, nutrient transport, eutrophication, aquatic ecosystem, thermal pollution, ecological exposure, alternative urbanization scenarios, biodiversity, streams, agricultural watershed, runoff, surface water, aquatic degradation, ecological impacts, eutrophication of lakes, urban development, agriculture, aquatic ecosystems, social constraints, water quality, Wisconsin (WI), channel erosion, impervious surface areas, irrigation, well location, nutrient cycling, aquatic biota, groundwater, land use, land management, storm water, pump stations, phosphorous, agriculture

    Relevant Websites:


    Progress and Final Reports:

    Original Abstract
  • 2000 Progress Report
  • 2001 Progress Report