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Stormwater Strategies
Community Responses to Runoff Pollution

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Chapter 5


In this chapter, the major themes presented in Chapter 1 are further distilled by taking a closer look at the case studies, and examining the key strategies that the highlighted communities have initiated to effectively address stormwater runoff. Through these actions, communities have been able to substantially reduce the impact from existing and new development, improve public understanding of and participation in stormwater pollution prevention, eliminate improper discharges to stormwater systems and receiving waters, control runoff and erosion from construction sites, and improve municipal operations and housekeeping practices. In taking these actions, many communities and developers across the country have also realized cost savings or financial gains, realized important secondary benefits, and overcome institutional barriers. While the case studies presented in the following chapters discuss the specific elements of these programs, the information in this chapter looks at the strategies collectively, examining the general strategy types as outlined below.

Addressing Stormwater in New Development and Redevelopment

  • Area-Wide Measures
    Growth Management
    Transportation-Oriented Design
    Watershed Planning
    Conservation and Performance Zoning
    Buffers and Open Space Preservation
    Brownfields Development and Infill Redevelopment
  • Site Design Measures
    Conservation Design
    Traditional Neighborhood Design
  • Site-Specific/Structural Runoff Control and Treatment Best Management Practices

Promoting Public Education and Participation

  • Encourage Pollution Prevention
    Alternative Landscaping
    Integrated Pest Management
    Vehicle Maintenance
    Waste Reduction
  • Promote Participation in Civic Activities
    Volunteer Water Quality or Outfall Monitoring
    Volunteer Inspectors
    Stream and Wetland Restoration and Clean-up
    Storm Drain Stenciling
    Public Hearings
  • Provide Information
    Training Workshops
    Master Gardener and Similar Programs
    Informing Local Decision Makers

Controlling Construction Site Runoff

  • Education and Training
  • Inspections and Enforcement
  • Erosion Prevention
  • Sediment Control

Detecting and Eliminating Improper or Illegal Connections and Discharges

  • Tracking and Detecting Discharges
    Routine Inspections of Sewer System
    Septic System Inspections
    Citizen Monitoring
    Community Reporting (Hotlines)
  • Prevention
    Facility Inspections
    Industrial Pre-treatment Programs
    Education and Training
    Incentive-based Certification Programs
  • Enforcement -- Legal and Administrative Actions

Implementing Pollution Prevention for Municipal Operations

  • Municipal Services
    Street Sweeping
    Leaf and Yard Waste Collection
    Recycling and Household Waste Collection
  • Municipal Activities
    Vehicle Fleets and Vehicle Maintenance
    Parks, Public Grounds, and Golf Course Maintenance
    Snow and Ice Control
    Requirements for Construction Contracts
  • Management of Storm Sewer and Pollution Control Infrastructure
    Catchbasin Cleaning
    BMP Selection, Monitoring, and Maintenance
  • Education and Training
    Training of Municipal Officials and Agency Personnel
    Certification of Non-Governmental Personnel

Addressing Stormwater in New Development and Redevelopment

See Box
Two Recent NRDC Surveys Document Progress and Gaps in Municipal Stormwater Management

By far the most important category of stormwater strategies focuses on land use and development. It encompasses a wide range of measures, from regional planning to the use of site-specific structural and nonstructural measures. These measures, with the exception of incentives for infill and redevelopment, apply more in developing and suburban areas than in ultra-urban areas that are already built up. In areas where there is less opportunity for regional or site planning or conservation-oriented design because they are already built up and largely covered by impervious surfaces, municipalities will need to rely more on the other elements of a stormwater program or on stormwater treatment measures.

As discussed in Chapter 2, one of the principal causes of urban stormwater pollution is the creation of impervious surfaces. One of the best strategies a municipality can employ is to minimize the aggregate amount of new impervious surfaces, since where impervious surface does increase, treatment or control of runoff is needed. The case studies demonstrate that minimizing impervious surfaces, within desired growth targets, can be a highly effective and beneficial strategy.

Several of the case studies discuss development that reduces impervious cover by concentrating houses on smaller lots. While this increases density and therefore the percentage of impervious cover on the developed portion of the site, it reduces the overall impervious cover, largely by reducing roads. Furthermore, by concentrating the impervious cover, it becomes technically easier and more cost-effective to implement structural runoff controls.

The discussion below first addresses area-wide measures that have been found effective, then moves to more site-specific designs, and finally looks at specific BMPs.


See Box
Statewide Programs: Building an Institutional Framework

The case studies demonstrate that comprehensive area-wide planning and nonstructural runoff control strategies are critical to the prevention of adverse environmental and economic impacts associated with urbanization. As one official said after review of a number of stormwater programs in a state: "In particular, the protection of the natural stormwater system, minimizing the creation of impervious surface, and minimizing the generation of pollutants will have a far greater benefit than any combination of structural practices."1

Coinciding with the country's renewed commitment to reduce stormwater pollution is a groundswell of concern about social issues such as traffic congestion, the abandonment of inner cities, and the demise of neighborhood communities.2 Efforts to address these problems, often broadly termed "smart growth," in many ways overlap with area-wide stormwater pollution prevention measures. Conversely, the case studies show that the stormwater measures discussed below can have numerous important social benefits that enhance quality of life and community well-being.3

Growth Management

Concentrating development in certain areas within an entire metropolitan area or region has the same benefits as concentrating development on a particular site. Less imperviousness is created for a given number of residences or businesses, creating less disturbance to the water cycle. Locally, however, the concentration of imperviousness will result in greater stormwater runoff and more polluted flows. Therefore, heavily urbanized areas will often require structural management measures of the type discussed later in the chapter.

A number of states including Oregon, Tennessee, Maryland, and Washington have enacted growth management regimes. Municipalities that have successfully implemented urban growth boundaries include: Portland, Oregon; Boulder, Colorado; Lancaster County, Pennsylvania; and several Bay Area cities. Establishing urban growth boundaries that encircle the current developed area of a particular city or metropolitan area reduces the amount of new development and associated impervious cover. In Olympia, Washington, the public works department recommended that reducing impervious cover be incorporated into the city's growth management efforts, with vehicle-oriented pavement offering the greatest opportunity for reduction.6 Disincentives that some cities use to discourage development outside these boundaries include large-lot zoning, municipal refusal to pay for sewers, roads, or other infrastructure, or concurrency requirements, which forbid development where municipal infrastructure has not yet been provided.7 However, in areas experience high growth pressure, such strategies may not be enough to stop sprawl. In the more successful programs, such disincentives are linked with incentives for infill or brownfield redevelopment to ensure that urban growth boundaries are not a moratorium on development. For example, urban growth boundaries are often coupled with other growth management techniques that encourage higher density development within the boundary, such as transfer of development rights programs. Several communities have used these programs, which allow developers outside the urban growth boundary or other areas of managed growth to sell their development rights to developers wishing to build at a higher density within the boundary.8

Percentage of Municipalities That Employ Each BMP -- Data from Two Surveys
Pollution Control or Prevention MeasureUsed by municipalities in 1998 national survey of coastal communitiesUsed by municipalities in 1998 Long Island Sound Surveya
Used oil collection60%78%
Street sweeping53%59%b
Septic system maintenance49%19%
Detention basins33%
Illicit connection enforcement32%
Storm drain steciling29%41%c
Erosion control ordinances29%94%
Public education25%63%
Stormwater screening17%
Municipal employee training16%72%
Municipal fleet maintenance14%
Stormwater Management Plan31%
Catchbasin cleaning88%d
Limits on fertilizer/pesticide use44%e
Limits on development69%f
Stream or wetland buffer88%g
Pooper scooper law38%
No information available18%
Source: NRDC, 1998

a New York and Connecticut towns, cities, and counties surveyed were combined to get overall percentages. New York villages, though part of the survey, are not included here.

b Sweeping occurs more than once per year

c Municipality performs stenciling or allows citizens to stencil

d Yearly cleaning or as needed

e Limits on at least one municipal operation or program

f Limits on at least one of the following: floodplains, increase in impervious surfaces, steep slopes, and highly erodible soils

g Some municipalities' programs fall under state programs

Transportation-Oriented Design

The experience embodied in these case studies demonstrate that alternatives to automobile transportation are feasible and realistic, and can be a key factor in reducing stormwater pollution. Regional planning provides a context for the development of bicycle routes and paths, and mass transit in the form of bus and rail systems or car pooling. Development concentrated within one part of a region makes all of these alternatives more useful for residents and makes public transportation more financially viable for the municipalities or regions that operate them. Even if development is not concentrated in one area, multiple nodes of concentrated development along public transportation corridors, known as transit-oriented development, can have the same effect. By concentrating development near transportation and commercial services, vehicle miles traveled are reduced as is the associated infrastructure. As previously discussed, fewer roads and vehicle miles traveled minimizes two principal components of stormwater runoff - impervious cover and pollutant discharge.

Watershed Planning

Watershed planning has provided several municipalities the opportunity to consider all the resources in the watershed as a single, interrelated system. As the name implies, watershed boundaries, not political boundaries, are the basic unit of management often requiring a municipality to work with other local governments or regional organizations. (A watershed is the land area, or catchment, that contributes water to a specific waterbody.)

Effective watershed planning focuses on the relationship between land use and water quality. Watershed planning begins with an evaluation of the current and desired condition for each of the relevant waterbodies in the watershed, as well as a comprehensive mapping of current land use practices in the watershed. Armed with these data, planners determine what land uses are consistent with the desired conditions in the waterbodies. Watershed residents and other stakeholders are usually involved in the process. The municipalities then put in place a watershed plan along with land-use ordinances that designate new development and land use changes to appropriate levels, types, and locations.16

Conservation and Performance Zoning

A few local governments have had success with watershed-based zoning, a parallel to conservation zoning. This strategy improves upon two conventional strategies for protecting watersheds: large-lot zoning and the widespread use of structural stormwater BMPs.17 Large-lot zoning can lead to an increase in net impervious cover by spreading development and infrastructure across an entire watershed. Structural stormwater BMPs can loose their effectiveness over time due to poor design and lack of maintenance.18 Furthermore, even at moderate levels impervious cover increases pollutant exports despite the presence of BMPs.19 Watershed-based zoning, on the other hand, regulates impervious cover rather than population density. Land use decisions are then made based on the relationship between stream quality and impervious cover.20

An alternative way to address stormwater pollution is performance zoning.21 Under performance zoning, a municipality does not specify uses for parcels of land as it may under traditional ordinances, but instead sets out performance standards for open space preservation, impervious surface area, maximum pollutant emissions, or other criteria that the municipality deems important. Some performance zoning ordinances grade proposed developments on a point scale based on the degree to which the development achieves various ends. Only development proposals with a point total exceeding a certain threshold then receive approval. In Maine, the potential impacts from a proposed development on phosphorus loading to lakes is calculated and compared to an established community goal. If the development causes the goal to be exceeded, the developer must modify the design or add additional control measures.22

Municipalities have found that taking these approaches to development has benefits beyond stormwater management. In many cases, they help preserve or enhance the desired character of a community and protect natural resources that are important to the residents. Researchers have found that clean water and healthy aquatic environments have significant value to the community and economy.23 Furthermore, using smart-growth management strategies reduce the cost of providing community services, such as public safety, water and sewer service, and roads.24

Buffers and Open Space Preservation

As Table 5-1 and the case studies show, many municipalities employ stream and wetland buffer requirements, open space preservation, and other laws or programs as cost-effective means for reducing stormwater runoff and achieving other public goals. These programs are often the specific means of implementing larger growth management goals and are often linked with incentives to aid development in other areas. In addition to zoning-type ordinances, municipalities can also use economic incentives to reduce impervious cover or implement stormwater control through stormwater utilities where the fee is based on amount of impervious cover, inspection and permit fees linked to compliance, or dedicated contributions from land developers.

Many local governments have had great success, apparently often more than they expected, with a buffer system of protected natural areas around waterbodies, sensitive areas, or steep slopes. Forested buffers are an essential part of natural stream, lake, and wetland protection.25 They often provide highly desired community amenities as well. Not only do buffers allow the water resource to function more naturally, they also help reduce a site's overall imperviousness. An average buffer width of 100 feet can reduce imperviousness by up to 5 percent of a watershed.26 Stream buffers often include the 100-year flood plain allowing the river system to naturally handle peak discharges, thereby avoiding expensive flood control structures. This aspect alone has saved governments millions of dollars. Furthermore, buffers act as filters, producing effective pollutant removal particularly for sediment, trace metals, and hydrocarbons.27 However, experience demonstrates that buffers cannot be relied on as the sole BMP due to the rapid concentration of runoff through pipes and channels; the more extensive and natural the buffer system, the more effective.

Other land acquisition and open space presentation programs have proven popular with local governments and, as judged by election and referendum results, with the electorate. In the 1998 elections, 10 states, at least 22 counties, and at least 93 local governments featured open space initiatives on their ballots. Voters approved 87 percent of the measures and a total of $4 billion of spending by their governments to protect open space, in many cases increasing taxes.28 Open space often serves many community needs and can both reduce the stormwater problem and be part of the solution. State assistance appears to be extremely helpful.

Brownfield Development and Infill Redevelopment

Policies to encourage brownfield or other redevelopment of existing facilities and new infill development in already developed areas can also help prevent stormwater pollution. Reuse and renovation of existing commercial buildings or industrial sites provides the opportunity for economic development with little or no addition of impervious cover -- and in some cases a reduction in such cover. Redevelopment and new infill development allows businesses and citizens to take advantage of existing municipal infrastructure. For example, mass transportation is usually more available in urban areas, helping reduce automobile use and thus pollution. Such infill development also reduces pressure to develop currently natural areas, the "greenfields," and can revive urban neighborhoods. For these and other reasons, brownfields development has been a top priority for many municipalities.29 The growing need to address stormwater should help his effort.

A key to all these area-wide measures is enforcement. Communities re-iterate the need to develop the financial resources and authority necessary to enforce standards and maintenance of stormwater controls before a problem or violation occurs. Many of the benefits of area-wide measures are dramatically reduced if not followed almost universally. In addition, unequal implementation and inadequate enforcement is unfair to those who do comply. To many local governments, this provides further justification of the need for effective public education as discussed below.


See Box
Better Site Design: The Center for Watershed Protection Site Planning Roundtable's 22 Model Development Principles

The case studies in this report highlight several communities and developers that have taken approaches that minimize overall imperviousness on a particular site. In many cases the developer initiated their approach independent of government requirements. Minimizing imperviousness, which is prevention focused, is more cost-effective than treating stormwater runoff and much more cost-effective than restoring waterbodies after they have been polluted or damaged.

The case studies also offer insight into a particular difficult aspect of this approach to stormwater pollution prevention. Often existing local or state regulators make stormwater-conscious site design more difficult due to street, set-back, density, or other site development requirements. While generally the case studies show that it is important that local governments enforce their regulations, in these circumstances it is important for local governments to allow flexibility.

Policies, programs, and regulations need to allow for innovation that favors the environment. If there are too many regulatory hoops to jump through or permits to submit, developers become discouraged from designing with nature in mind, even if it benefits them financially.30 While providing flexibility that protects the environment may seem inconsistent with prohibiting flexibility that harms the environment, it appears that many municipalities have succeeded in so doing. It represents a sound governmental policy.

Conservation Design

Conservation-design development concentrates homes on a limited percentage of the land comprising a residential subdivision, while leaving the rest of the land as open space.31 As several of the case studies show, conservation design also reduces the amount of impervious road surface created, since the homes are not spread as far apart, and preserves a much greater percentage of undeveloped land. Narrower roads, shorter setbacks from residential streets that allow shorter driveways, or shared driveways also reduce impervious cover when designing residential developments.32

The concepts of conservation development design have recently been expanded by ecologists to integrate native landscapes as functional elements of a development to provide water quality management, wildlife benefits, biodiversitiy protection, and human enjoyment. This is very different from the approach of simply not developing certain areas.33 For example, some developments using all the land as part of a stormwater treatment train and have a committed restoration and management program for all portions of the property in order to maintain ecological integrity and water management functions.34

On commercial and municipal sites, developers have frequently minimized imperviousness by implementing alternative parking arrangements. For example, businesses with parking demands at different times, such as a medical practice and a restaurant, have successfully shared the same parking area. Other parking alternatives used consist of planning lot capacity for average rather than peak parking demands, placing parking areas beneath commercial buildings, and constructing multistory parking garages.35

Another tool to reduce overall imperviousness, is apparently becoming more popular. Porous pavement allows water to pass through it into the soil while retaining enough strength to support vehicular traffic. (It has largely been used in areas of light to moderate, not heavy, traffic.) Porous asphalt and concrete differ from regular asphalt and concrete because fine materials are not added to fill in the gaps between the coarser aggregate in the pavement material, so that myriad small holes allow water to infiltrate.36 Grass paving systems use plastic or concrete grids buried at soil level to add strength to normal turf. While perhaps not suitable for daily use, grass paving may be appropriate for parking areas used intermittently. Some experience suggests, however, that pervious pavement can require more maintenance.

Preservation of sensitive areas has helped address runoff on a site-specific basis as well as on an area-wide basis, as discussed above. On their own and not due to area-wide requirements, numerous extremely successful developments have kept imperviousness to a minimum and protected sensitive areas by specifying buffer zones around waterbodies and by not developing areas where steep slopes, forests, or wetlands are present. Such developments, including Prairie Crossing in Grayslake, Illinois, have sold as well as or better than standard subdivisions, maintain their value better, and are more community friendly. In addition, the lower total runoff translates directly into savings on stormwater control and treatment measures.

Traditional Neighborhood Design

A more comprehensive approach to site-specific planning is the traditional neighborhood developments (TNDs).37 Although aesthetic or cultural concerns motivate many proponents of TNDs, environmental concerns are also advanced with TNDs. Like conservation-design developments, TNDs have sought to minimize the impervious "footprint" of the built environment and preserve open space through compact development patterns that feature narrower roads, shared alleyways, smaller lots, and smaller front setbacks from the street. However, TNDs in the case studies go a step further by adding the principle of mixed-use development. At their best, TNDs provide stores, offices, schools, day-care centers, recreational opportunities, and mass-transit facilities all within a short walk of residents' homes. This gives residents the option to walk rather than drive and thereby eliminate some of the 12 automobile trips that the members of an average suburban household make each day.38

It is important to note that TNDs may create areas of very high impervious cover, which create large volumes of contaminated runoff requiring treatment by the structural measures described below. But the compact style of development minimizes the amount of impervious cover over the broader landscape. This way, overall imperviousness in a community or watershed and accompanying stormwater runoff problems are reduced.


The management measures discussed above seek to preserve natural infiltration and pollutant-removal capabilities and reduce generation of stormwater pollutants. This is clearly the most effective and cost-effective method of stormwater pollution prevention. Depending on the circumstances, however, these types of measures may not be adequate to deal with stormwater problems caused by new development or redevelopment, and are usually insufficient in areas already fully developed. Where new development is concentrated in one area, for example, the stormwater from that highly developed area needs more intensive management. In places where infilling is occurring or where land is less available or more expensive, there is often less interest in area-wide measures.

In such cases, municipalities then turn to site-specific runoff control and treatment. Typically, these BMPs are structures engineered to remove contaminants from runoff and to control its flow.39 These structural BMPs are best suited to -- and may be the only option available for areas of dense impervious cover. In highly urbanized areas where space is limited, retrofitting an existing stormwater control structure to be a treatment structure has proven an effective strategy.

The case studies below, as well as other experience in highly urbanized areas, both demonstrate the need for structural BMPs in treating and controlling stormwater runoff from developed areas, as well as the frequent relative advantage of the nonstructural strategies where they are possible. For some types of treatment, structural BMPs may involve significant construction, usually at a comparatively high cost, and require continued operation and maintenance. Critical to the effectiveness of structural BMPs are proper design and installation that considers site-specific conditions. Furthermore, structural methods only partially mitigate the impacts of urbanization.40 Nonstructural BMPs, on the other hand, are prevention-focused and therefore often achieve greater environmental benefits. They are also very cost-effective; an ounce of prevention is worth a pound of cure. Structural stormwater "cures" can also have unfortunate side-effects; for example, wet ponds and detention basins cause an increase in water temperature, which impacts aquatic organisms.

The bottom-line from these case studies appears to be that while prevention-focused, "nonstructural" BMPs such as planning and design offer many advantages, in the densely populated sections, some structural BMPs are often needed. Where there are highly impervious areas, where there is not the land available for natural area methods, where extensive quantitative information in needed,41 municipalities turn to structural measures.

Four categories of structural management measures are found in these case studies: detention practices, biofiltration practices,42 infiltration practices, and filtration practices. Some of the greatest successes have come from using more than one of these four functions in series, sometimes referred to as a stormwater treatment trainTM. Other successes have been achieved by retrofitting detention and retention systems to add stormwater treatment components to existing conveyance or storage facilities.

Detention Practices

Several of the case studies that follow highlight detention as a stormwater control practice. Detention practices temporarily store runoff, then discharge it through a pipe or other outlet structure into streams or other waterbodies.43 Use of wet and dry detention ponds are the most common such practices. Dry ponds release all of their water within a specified time period (generally up to 48 hours), while wet ponds keep some water at all times and retain excess water for a longer period than dry ponds. When designed to be such, wet ponds can be an aesthetic or recreational amenity. Another less common detention practice is the use of cisterns.

The fundamental purpose of detention ponds is to reduce peak flows. They also can improve water quality by holding water for a long enough period to allow some sediment and other contaminants to settle out before the water drains. Wet ponds, by virtue of the longer detention times and frequent presence of aquatic plants and other life, can provide additional water quality treatment through biofiltration (see below) and chemical processes.

Biofiltration and Bioretention Practices

Biofiltration and bioretention practices are discussed in several of the case studies in this report. These practices filter stormwater to reduce contaminant loadings using plants as an additional filter medium. Plants absorb nutrients and metals to a certain extent and facilitate microbal breakdown, but most of the pollutant removal from these practices occurs when the presence of the plants physically blocks the stormwater flow, slowing the flow and allowing contaminants to settle out.44 Bioretention areas, also known as rain gardens, capture runoff and allow it to slowly infiltrate into the ground. Infiltration enhances pollutant removal and allows the water to be cooled. As with other structural BMPs, occasional maintenance to remove the accumulated pollutants that have been taken from the stormwater is required.

Municipalities use several types of biofiltration. Constructed wetlands are artificial versions of natural wetlands, using shallow bodies of standing water filled with reeds and other wetland vegetation to filter the water. Engineered filter strips are slightly sloped, flat land planted with grasses, trees or other vegetation which remove stormwater pollutants as the stormwater moves gently across the strip in a even, sheet-like flow. Swales are wide ditches with moderate sloped banks and bottoms covered with filtering turf; in many cases swales also permit infiltration as well as clean the water. Bioretention areas are constructed forested or vegetated beds, usually composed of gravel, soil, trees and shrubs, a sand layer, and a grassed swale.

Infiltration Practices

Infiltration practices temporarily store runoff in basins from which the water percolates slowly into the soil below. Like detention practices, they reduce peak flows. However, infiltration practices also recreate, to a greater or lesser extent, the natural pattern of water infiltration into the ground that existed before increased imperviousness covered the land. When designed and installed correctly and maintained regularly, infiltration practices are among the most effective structural BMPs, and often address most of the stormwater impacts previously discussed. Studies have shown that infiltration of the can get 98 percent of stormwater into the earth, cool stormwater to 55F, remove up to 83 percent of nitrogen, and remove up to 98 percent of copper.45 The principal reason why infiltration is often a preferred method is that runoff is cooled as it flows though the ground, thereby reducing the detrimental thermal effects that runoff has on aquatic ecosystems.

Local governments have used a wide variety of infiltration practices; several are discussed in the case studies that follow. "Retention" basins look like dry detention ponds, but have no outlet, forcing water to infiltrate through the bottom of the basin.46 Infiltration trenches are generally filled with rocks and gravel to surface level, creating a reservoir that holds water until it passes into the surrounding soil. Dry wells are deeper, narrower versions of infiltration trenches. Some of the most successful are wide-spread use of "french drains," small infiltration trenches placed at the bottom of the discharge pipe from roof gutters that allow water to infiltrate on site rather than passing into the storm sewer system.

Filtration Practices

Filtration practices address water quality problems rather than water quantity. Some consist of a chamber containing a filter medium buried at ground level through which stormwater flows, while some are filter inserts for catchbasins in the storm sewer system. As stormwater flows pass through the filter medium, it removes particulates and other contaminants. The filtering materials most frequently used are sand, peat, or compost, although municipalities now use BMPs with synthetic filter media.47

The case studies and literature show that many programs have successfully reduced stormwater pollution using the measures mentioned above. It is important to note, however, that these measures are not magic bullets and need to be carefully evaluated and monitored in order to ensure effectiveness. For example, some studies have shown that pollutants can accumulate in wetlands, and in some cases may approach levels of concern, yet little is know about the long-term effects of contaminants on these systems.48 Studies have also shown that wetlands may transform some pollutants such as mercury into more problematic forms.49 Catchbasin inserts and filtration devices can loose effectiveness over time due to clogging or structural failure, or may not work well under certain conditions.50 To remain effective, these systems must be carefully selected, monitored, and maintained. Infiltration basins are not appropriate in certain areas, depending on soil and water table. Areas near vulnerable ground water resources such as drinking water recharge areas, or in areas with a high likelihood of contaminated runoff such as industrial sites or major roads and highways should be avoided. Detention ponds allow warm stormwater to enter directly into receiving waters. Stormwater collected in ponds may heat to 95 F or more on a hot summer afternoon.51 Since aquatic ecosystems are sensitive to changes in water temperature, these warm waters can cause a loss of fish and other aquatic organisms. For these and other similar reasons, experts recommend that a combination of BMPs be used to broaden treatment, improve effectiveness, and avoid undesirable side effects. Furthermore, the case studies and research for this report demonstrate that the most successful programs choose stormwater BMPs based on site use and characteristics as well as the targeted pollutants and established removal goals.

Postconstruction stormwater management is in many municipal officials' minds the most significant element of a stormwater plan. This category of measures -- planning, site design, constructed facilities -- attempts to reduce the overall impact of stormwater from developed, or developing, areas. While this represents the most far-reaching stormwater measures, the most successful strategies documented in the case studies link postconstruction stormwater management to the other measures discussed below: public education, construction site controls, elimination of illegal discharges and illicit connections, and improved municipal practices.

Promoting Public Education and Participation

See Box

Experience demonstrates that local governments need, and can get, the support of the broader population in addressing stormwater pollution. Individuals play a key role in reducing stormwater impacts both in their own day-to-day activities and in showing support for municipal programs and ordinances. The case studies presented have suggested that the effectiveness of BMPs in other categories is often tied to the effectiveness of the public education program.

Public education, outreach, and participation form the link between the local governments and its citizens. Education programs encouraging citizens to change their habits in activities such as caring for lawns, driving and maintaining cars, and walking pets, and to contribute to cooperative efforts often form an early element of a municipal stormwater program.

Public education programs documented in the case studies have been successful in addressing a wide range of activities. For example, programs encourage citizens and businesses to reduce the chemical pesticides and fertilizers used on their lawns and gardens, or switch to natural pesticides and fertilizers. Education programs can also encourage alternative landscaping practices, such as the use of native plants. They advocate and teach citizens about integrated pest management, a comprehensive approach that emphasizes selection of pest-resistant plants, careful monitoring of pest infestation levels and setting realistic tolerance levels for those infestations, and reliance whenever possible on alternative strategies to reduce pest infestation. These practices minimize the quantity and toxicity of pesticides used and thus reduce the toxicity of runoff. The case studies suggest that success regarding used oil and yard waste collection is largely dependent on public education programs alerting citizens to the program and encouraging them to use it.

Public education may also take the form of promoting participation in civic stormwater control activities. Municipalities have allowed, encouraged, or assisted neighborhood groups to paint stencils near storm drains with a message such as "Don't Dump; Drains to Bay."

Programs also have allowed or assisted citizens to monitor water quality in local waterbodies or inventory and sample stormwater outfalls. Restoration projects -- repairing damaged waterbodies by cleaning up debris dumped in streams or wetlands or by helping out with streambank stabilization -- both achieve immediate environmental results and have proven to be among the most successful public education programs. Municipal education programs appear most successful if carefully targeted. School children, homeowners, business operators, outdoor recreation enthusiasts all have different interests; the most effective material distinguishes among different audience and provides information interesting to them. In particular, public education targeted at local businesses can offer them ways to contribute to citizen efforts or can focus on a pollution problem that is particular to a specific sector. Education efforts focused on gas stations, car washes, or lawn care companies have made important progress. (Education efforts tailored to construction activities are discussed below.)

Another form of public participation is participation in the political process. Municipalities reap multiple rewards encouraging citizens to participate in public hearings concerning stormwater management ordinances and programs, growth management regimes, approval for highway or residential development projects, public transit planning and budgeting, and other government activities affecting stormwater pollution.

Public education and outreach uses many techniques. Local governments have used passive means such as radio and television advertisements or programs, newsletters and educational brochures, web sites or toll-free telephone lines. Municipalities have also used more participatory means: games and educational activities for children, workshops and presentations for businesses and community groups, in-school programs, preferably at each grade, and tours of areas affected by stormwater pollution. One particularly effective outreach technique is mentoring, in which an experienced volunteer serves as a "master" and assists a newcomer in learning environmentally beneficial practices. This practice has worked particularly well in the area of alternative lawn-care and gardening methods.

Providing decision-makers with quality and accurate information is partly education, partly municipal operations, and partly planning. By focusing on familiar issues and local examples, these programs help place broad, complex issues into context. Ideally all municipal officials will think about the stormwater implications of their decisions. Technologies such as geographic information systems (GIS) help demonstrate the relationship between impervious cover, stormwater runoff, and water quality, and enable officials to compare water resources with projected future levels of development, estimated from a zoning-based build-out analysis.55 This provides the ability to see into the future and assess impacts from development on a community and its water resources.

The most successful of the education/outreach programs highlighted below accomplish three goals. First, they educate people about the nature of the urban stormwater pollution problem -- its causes and consequences. Second, they inform people about what they can do to solve the problem. Finally, since hands-on education is often the best, the program achieves either pollution reduction or restoration targets.

The case studies emphasize that successful public education does not come without careful thought and design. Specific targeting and understanding of the audience is critical. NRDC's research for this report found excellent programs but also many poorly conceived and ultimately not very successful education programs. Furthermore, it is important that these programs be evaluated regularly to make sure that messages are getting out and behavior is actually changing.

Controlling Construction Site Runoff

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Key Elements that Enable Local Governments in Most Climate Regions to Protect Their Waters

While construction is just one of many industries with stormwater impacts, its impacts are so significant that it is treated separately under the federal and most state and local programs. As noted in Chapter 2, a short-term construction project can produce as much stormwater pollution as years of other activities. The case studies below demonstrate that effective construction pollution prevention is politically and economically feasible and can dramatically reduce this pollution. In addition, these measures can have benefits for the developer as well: control measures such as phasing, mulching, and revegetation not only reduce erosion, but also have proven repeatedly to increase the value of the property.56

Effective local construction site stormwater management strategies aim both to reduce runoff volume to levels that will not cause erosion and to capture as much of the sediment and other pollutants that do wash off. While existing programs rely on a fairly wide variety of erosion and sediment control practices virtually all successful strategies require proper planning and phasing of construction activities to avoid disturbing more land than necessary during construction.

The case studies demonstrate that the most effective local programs rest on four cornerstones laid in pairs: enforcement and education; erosion prevention and sediment control. However, the first and over-arching necessity is a clear set of requirements. The research for this report indicates that vague guidelines or performance standards achieve vague results. Clarity and as much detail as possible is directly linked to the degree of implementation and ultimate success.

From the case studies, it appears that, even more than with respect to other industries, education and enforcement can achieve measurable stormwater pollution reduction. Effective education programs surveyed include a few essential elements: close cooperation with both local developers and citizen groups; a variety of outreach and communication modes, including brochures, training workshops, and on-site assistance; and clarity in communicating both regulations, and technical methods. Compiling a set of clear, performance, BMP, and design-based standards, from the federal, state, and local requirements in one easy-to-read manual or booklet appears helpful. Many effective construction-site education programs also employ contractor certification to help ensure a baseline of knowledge for the development community.57 Whatever the education program however, they have not proven successful without the accompanying "teeth" of enforcement.

Effective enforcement programs are found to require staffing adequate to the intensity and total acreage of development activity, stable funding, frequent inspections, clear enforcement authority, and partnerships with citizens. In addition, success is often greatly enhanced where top local elected and appointed officials make it clear they will not tolerate anyone not meeting environmental requirements.

NRDC's research into successful strategies suggests that enforcement authority must be, but often is not, vested at the appropriate local government level. For instance, in regions with strong "homerule," the authority to control clearing, grading, planning, and construction activities is usually extremely fragmented among many small towns while county-level planners and officials with a regional view of violators, patterns of development, and stream conditions, may have virtually no enforcement authority over construction. Better programs have frequent inspections by staff knowledgeable about all aspects of a development and potential impacts and with close contacts to a ready enforcement staff.

Local governments' partnerships with citizens have added successful strategies in a number of ways. Partnerships training citizens in construction requirements offer additional eyes and ears watching sites for compliance.58 Many jurisdictions staff a hotline to receive and act on citizen complaints of non-compliance.59 Partnerships with developers that provide some successful incentives such as positive publicity for good actors also appear popular and effective in the studies.60

The second pair of cornerstones of effective construction stormwater strategies are erosion prevention and sediment control measures. Common erosion prevention techniques use site planning and construction phasing to minimize the unregulated areas exposed at any one time and shelter graded or denuded soil from rain and snowmelt. Sediment controls attempt to capture sediment after it has eroded off a hillside or graded area, using collection devices such as sediment basins or inlet filters, or controls such as silt fences at the perimeter or throughout larger sites.

As noted above, the more effective programs have both elements. Unfortunately, however, even though a 1997 national survey found erosion prevention practices (site design, planning, and phasing) are commonly capable of reducing 90 percent of suspended solids leaving a construction site, while most sediment control devices (filters and fences) have much lower efficiencies,61 many local governments pay less attention to erosion prevention. Unfortunately, it appears to take less effort to require sediment controls for construction sites than it does to pair them with effective erosion prevention, perhaps because sediment control can usually be done -- or at least attempted -- without much alteration of a site's design, grading and scheduling plans, while effective erosion prevention will often affect these aspects of a site plan. Thus, while prevention is far more effective than end-of-pipe treatment, it is less common. By far, one of the most important conclusions of this research effort is the need to increase erosion prevention programs, and the value in doing so.

Erosion prevention practices are an element of the more successful strategies because they can keep from mobilizing the more harmful fine-grained particles that sediment controls cannot capture. In addition, erosion prevention techniques often require less maintenance since they are "planning-based" and non-structural.

It is also important for contractors to protect sensitive areas such as steep slopes, sensitive soils, wetlands, and other water resources. Effective programs prohibit construction activities near sensitive areas or require measures to protect those features using vegetated buffers, silt fences, and dikes. In some cases municipalities have stricter requirements or ask for more detailed erosion and sediment control plans for sites containing sensitive areas.

A 1994 survey of 43 local governments nationwide found many gaps in erosion prevention. For instance, fewer than a fifth of the local governments surveyed reported that they required that a minimum portion of each site must remain undisturbed. A third of respondents said they impose no time limit for revegetation of exposed areas. Little more than a third prohibit by law the clearing of steep slopes.62 Clearly, this is an area with tremendous opportunity to make an environmental difference.

A final element of successful construction stormwater strategies addresses chemicals and other hazardous substances out of stormwater. Proper operation, maintenance, and storage of heavy equipment and materials prevents oil, gasoline, paints, solvents and the like from leaking or spilling onto the ground. Municipalities use a range of education, enforcement and incentive programs to achieve this goal.

Detecting and Eliminating Improper or Illegal Connections and Discharges

Local governments have found that identifying and eliminating illicit connections and discharges is a remarkably simple and cost-effective way to eliminate some of the worst pollution from stormwater and to improve water quality. The case studies demonstrate that two factors are critical to success of this element of stormwater programs: tracking or finding illicit connections and discharges and enforcement. Since connections to storm sewers are usually underground, discouraging illicit connections is not always easy. Routine inspections or system surveys help prevent this problem. Enforcement is necessary to ensure that the problem once found is dealt with quickly and appropriately. These activities are also necessary to maintain support for the broader stormwater program since, absent investigation and enforcement, the illegal dischargers may be getting an advantage over the law-abiding members of the community, thus souring the honest actors on stormwater pollution prevention.

Individuals or businesses may dump waste oil, excess pesticides and other chemicals, or simply trash and yard waste into storm drains as a cheap and dirty way to dispose of unwanted materials. In other cases, businesses or individuals connect wastewater lines from toilets, sinks, floor drains and industrial processes to the storm sewer system rather than to the sanitary sewer system. Sometimes these illegal connections date from long ago and are unknown, other times they are recent attempts to avoid service charges or the like. Effective municipal responses distinguish, when possible, between these situations.

In addition to these intentional illegal discharges, negligence adds to stormwater pollution. When people store materials outside, or spill or dump oil or chemicals on the ground, stormwater picks the substances up and transports them to receiving waters. Septic systems overflow and leave sewage on the ground. Sanitary sewer lines leak and discharge pathogens and nutrients from residential wastewater and chemicals from industrial wastewater into nearby storm sewer lines. Many non-industrial, and often unregulated, improper discharges also degrade water quality, including household and charity car washing; mobile pressure washing of buildings, parking lots, and industrial equipment; draining swimming pools; and irrigating lawns and gardens.

To find illegal discharges and illicit connections, the most successful programs use a range of techniques. Municipalities inspect septic systems to insure that they are well-maintained and large enough to handle expected sanitary flows, facilities such as landfills, service stations and industrial or commercial sites that store materials outside to insure that pollutants are removed or properly stored, and their own facilities for the same problems. They also inspect the sanitary sewer systems for leaks and overflows and the storm sewer systems for dry weather flows signifying illicit wastewater connections from homes and businesses.

Industrial pre-treatment programs also offer a good opportunity to inspect facilities for illicit connections and the potential for improper runoff discharges at little extra cost since an inspector is already at the site. Several municipalities also get citizens involved in identifying and reporting illicit discharges and connections by providing a 24-hour hot line. Utility bill flyers and other educational efforts inform citizens of the program.

In addition to performing inspections, successful municipalities train inspectors to offer compliance assistance to businesses and homeowners where appropriate. In may cases, compliance assistance overlaps with a targeted public education effort. Several successful strategies have aided compliance by bringing into one handbook all applicable federal, state, and local requirements for an activity. Incentives such as certifying and promoting a business as a green business if they come in compliance have also encouraged the elimination of illicit discharge sources.

Finally, effective programs include enforcement authority. Such programs can use fines and citations to punish illicit dumping of waste materials on land or in the storm sewer system and to compel the removal of illicit connections to the storm sewer system. Municipalities enforcing against intentional illegal dumping or connections have encountered community support for their efforts, not opposition. For the non-venial dischargers, offering household hazardous waste and pollutant collection days and facilities can effectively reduce improper discharges to the storm system.

Enforcement and education are closely linked. Enforcement engenders less opposition when people know what they are supposed to do and why. Conversely, enforcement appears to be a great motivation to pay attention to education efforts. One city official found that "The more educated people become, the more strict we're able to be in our enforcement of the rules."63 Phrased differently, as a local activist said, "The best education program is a good enforcement program."64 As noted before, stormwater management efforts build synergistically off each other; the most successful municipal strategies cover all program elements effectively.

Implementing Pollution Prevention for Municipal Operations

A wide range of municipal operations can affect stormwater quantity and quality. NRDC's case studies reveal that some local governments have been able to manage their municipal operations to make a significant positive contribution to reducing stormwater pollution. Successful municipal operations stormwater strategies address areas of municipal activity (in addition to planning and regulatory/enforcement efforts discussed above) in a variety of ways.

First, a number of municipal services primarily provided for other purposes can curb stormwater pollution. Street sweeping, collection of leaves and other yard waste, collection and recycling of used oil or other substances, and general trash control all keep contaminants out of urban runoff. Improvement or expansion of such programs significantly assists stormwater pollution prevention, and because people want these programs, builds support for the broader issue of stormwater management.

Second, municipalities engage in a number of activities that directly cause stormwater pollution. They operate and maintain vehicle fleets of municipal buses, police cars, and garbage trucks. These vehicles emit into the atmosphere nitrogen and particulates which eventually end up on the ground and then in the stormwater. These vehicles also deposit oil, grease, and metals onto roads and parking lots. Municipalities apply pesticides and fertilizers to municipal parks, cemeteries, highway rights-of-way, and golf courses. Local governments in colder parts of the country salt or sand roads to control ice and snow. The programs gathered here demonstrate that with modest effort local governments can significantly reduce or eliminate the contribution to stormwater pollution arising from these activities.

Municipalities can include stormwater control requirements in all contracts for construction work and other contracts where such provisions are relevant. Most simply (and a very common action), timely maintenance of vehicles reduces the amount of oil, grease and metals left on roads and parking lots. More dramatically, municipal fleets can be converted to low-emission or zero-emission vehicles powered by natural gas, electricity, or other energy sources to reduce emissions and thus deposition of nitrogen and particulates. A number of municipalities reduce or even eliminate the use of artificial pesticides and fertilizers by employing sound landscaping practices such as planting native species and using integrated pest management. Municipalities and transportation departments have found it is relatively easy to monitor road salt and sand needs to avoid applying more than necessary, which saves money as well.

Third, municipalities often manage some type of storm sewer or storm drain system; how they do so can make the difference between simply moving the water to another place and successfully addressing stormwater pollution. For example, if catchbasins are not properly cleaned, the materials that collect in them -- sediment, trash and other stormwater contaminants -- can be resuspended in stormwater during a storm and eventually flow into a stream or waterbody. Local governments have found effective designing devices to reduce velocity using vegetated swales to facilitate infiltration and purify stormwater runoff, or using preserved natural areas to store or convey stormwater.

Fourth, training and education efforts that target municipal officials and agency personnel have also proven to be important. Park and utility workers educated in integrated pest management, fertilizer use, and composting; fleet workers educated in fluid disposal; construction workers educated in erosion controls -- all these have made noticeable differences in the stormwater impacts of municipal operations. In municipalities constrained by human resources, programs that provide training or certification for non-government personnel, such as citizen construction site or stormdrain and outfall inspections have proven effective. Furthermore, the case studies demonstrate that a well-trained and informed staff improves interactions with the community, raising community awareness, improving credibility, and setting positive examples for the community.

Finally, although no local government surveyed had a full program in this area, several local government officials strongly recommend that periodic environmental audits would make any program far more successful. A broad-based audit would be particularly useful regarding problems such as stormwater that reflects a cumulation of numerous minor problems. With environmental audits becoming more popular in industry, methods for such audits of local governments should be fairly readily available.


1. Livingston, E. H., "Successful Stormwater Management: Selecting and Putting the Puzzle Pieces Together," Florida Department of Environmental Protection, Stormwater/Nonpoint Source Management Section, Tallahassee, Florida, 1997, p. 7.

2. Gore, A., "Livability Announcement." Federal Document Clearing House, Inc., January 11, 1999.

3. For more information on Smart Growth see: Benfield, F. K., M. D. Raimi, D. D. T. Chen, Once There Were Greenfields: How Urban Sprawl is Undermining America's Environment, Economy, and Social Fabric, Natural Resources Defense Council, New York and Surface Transportation Policy Project, Washington, D.C., 1999; Urban Land Institute, "Smart Growth: Economy, Community, Environment," Urban Land Institute, Washington, D.C., 1998, 56 pp.

4. Natural Resources Defense Council, Long Island Sound Municipal Report Cards: Environmental Assessment of 78 Coastal Communities, 1998, pp. 188.

5. Natural Resources Defense Council, "Stormwater Impacts: A Survey of 119 Coastal and Great Lakes Municipalities," Draft report, 1998.

6. City of Olympia, Public Works Department, Impervious Surface Reduction Study. May 1995, p. 5.

7. A comprehensive review of urban growth management methods is available in Chris Duerksen, Erin Johnson & Cheryl Fricke, Colorado Growth Management Toolbox, Clarion Associates, January 1995, pp. 2435.

8. Nelson, A. C. and J. B. Duncan, with C. J. Mullen and and K. R. Bishop, Growth Management Principles and Practices, Planners Press, American Planning Association, Washington, D.C., 1995, pp. 4751.

9. Livingston, E. H. and E. Shaver, "Institutional Aspects of Urban Runoff Management: A Guide for Program Development and Implementation," Watershed Management Institute, Inc., Crawfordville, Florida and U.S. EPA Region 5, Chicago, Illinois, January 1997, pp. 4-44-5.

10. Livingston, E. H. and E. Shaver, "Institutional Aspects of Urban Runoff Management: A Guide for Program Development and Implementation," Watershed Management Institute, Inc., Crawfordville, Florida and U.S. EPA Region 5, Chicago, Illinois, January 1997, pp. 4-44-5.

11. D'Antuano, J. R., "Stormwater Permitting in the Milwaukee River Basin," Proceeding for Water Resources and the Urban Environment, American Society of Civil Engineering, Chicago, June 1998, 6 pp.

12. Wisconsin Natural Resources Code (N216).

13. Bateman, M., E. H. Livingston, and J. Cox, "Overview of Urban Retrofit Opportunities in Florida," Florida Department of Environmental Protection, Tallahasee, Florida, 1998, 18 pp.

14. Bateman, M., E. H. Livingston, and J. Cox, "Overview of Urban Retrofit Opportunities in Florida," Florida Department of Environmental Protection, Tallahasee, Florida, 1998, 18 pp.

15. Bateman, M., E. H. Livingston, and J. Cox, "Overview of Urban Retrofit Opportunities in Florida," Florida Department of Environmental Protection, Tallahasee, Florida, 1998, 18 pp.

16. Schueler, T.R., Site Planning for Urban Stream Protection, Metropolitan Washington Council of Governments, December 1995, pp. 3753.

17. Schueler, T. R., Site Planning for Urban Stream Protection, Metropolitan Washington Council of Governments, December 1995, pp. 3753.

18. Schueler, T. R., P. A. Kumble, and M. A. Heraty, A Current Assessment of Urban Best management Practices: Techniques for Reducing Non-point Source Pollution in the Coastal Zone, Metropolitan Washington Council of Governments, March 1992, 127 pp.

19. Schueler, T. R., "The Importance of Imperviousness," Watershed Protection Techniques, vol. 1, no. 3, Fall 1994, pp. 102.

20. Schueler, T. R., Site Planning for Urban Stream Protection, Metropolitan Washington Council of Governments, December 1995, pp. 4345. Schueler, T. R., P. A. Kumble, and M. A. Heraty, A., Current Assessment of Urban Best Management Practices: Techniques for Reducing Non-point Source Pollution in the Coastal Zone, Metropolitan Washington Council of Governments, March 1992, pp. 12.

21. NRDC has based the following description of performance zoning on Chris Duerksen, Erin Johnson & Cheryl Fricke, Colorado Growth Management Toolbox, Clarion Associates, January 1995, pp. 3738.

22. Maine Department of Environmental Protection, Phosphorus Control in Lake Watersheds: A Technical Guide to Evaluating New Development, Revised, September 1992, p. 4.

23. Some references discussing the economic value of environmental resoureces include: Burt, O. R. and D. Brewer, "Estimation of Net Social Benefits From Outdoor Recreation." Econometrica, Vol. 39, No. 5, 1971, pp. 813827; Diamont, R., J. G. Eugster, and C. J. Duerksen, A Citizen's Guide to River Conservation, The Conservation Foundation, Washington D.C., 1984, pp. 97103; Freeman, M. A., "Hedonic Pricing Methods," in: D. W. Bromley, Handbook of Environmental Economics, Blackwell Publishers Ltd., Cambridge, 1995; Hoehn, J., T. Tomasi, F. Lupi, and H. Chen, An Economic Model for Valuing Recreational Angling Resources in Michigan, Volume 1, Michigan Department of Environmental Quality and Michigan Department of Natural Resources, Lansing, MI, 1996; Vaughan W. J. and C. S. Russell, "Valuing a Fishing Day: An Application of a Systematic Varying Parameter Model." Land Economics, Vol. 58, No. 4, 1982, pp. 450463; Apogee Research, Inc., Analyzing Employment Effects of Stream Restoration Investments, Final Report, U.S. Environmental Protection Agency and U.S. Army Corps of Engineers, IWR Report 94-FIS-18, November, 1994, pp. 4142.

24. Some references discussing the cost associated with sprawl development include: Real Estate Research Corporation, "The Costs of Sprawl: Executive Summary," U.S. Government Printing Office, Washington, D. C., April 1974; Frank, J. F. The Costs of Alternative Development Patterns: A Review of Literature, Urban Land Institute, Washington, D. C., 1989, p. 39; Burchell, R. W., "Impact Assessment of The New Jersey Interim State Development Plan-Executive Summary," Rutgers University Center for Urban Policy Research, February 1992, 28 pp.; Benfield, F. K., M. D. Raimi, and D. D. T. Chen, Once There Were Greenfields: How Urban Sprawl is Undermining America's Environment, Economy, and Social Fabric, Natural Resources Defense Council and Surface Transportation Policy Project, 1999.

25. Schueler, T. R., Site Planning for Urban Stream Protection, Metropolitan Washington Council of Governments, December 1995, pp. 13, 87.

26. Schueler, T. R., Site Planning for Urban Stream Protection, Metropolitan Washington Council of Governments, December 1995, pp. 9293.

27. Schueler, T. R., Site Planning for Urban Stream Protection, Metropolitan Washington Council of Governments, December 1995, p. 95.

28. Land Trust Alliance, "Voters Invest in Open Space," Press release, November, 1998.

29. United States Conference of Mayors, Brownfields Task Force, "The United States Conference of Mayors Brownfields Redevelopment Expanded Action Agenda," Winter 1998, http:

30. Maryland Office of Planning, Managing Maryland's Growth: Models and Guidelines, April 1995, pp. 25.

31. Key references concerning conservation-design subdivisions and site planning for stormwater control and open space protection are: R. G. Arendt, Conservation Design for Subdivisions: A Practical Guide to Creating Open Space Networks, Island Press: Washington, 1996; R. G. Arendt et al, Rural by Design: Maintaining Small Town Character, American Planning Association: Chicago, 1994; and T.R. Schueler, Site Planning for Urban Stream Protection, Metropolitan Washington Council of Governments: Washington, December 1995.

32. The City of Olympia, Washington, has prepared a comprehensive study of imperviousness reduction techniques mentioned in this paragraph and the following one. City of Olympia Public Works Department, Impervious Surface Reduction Study, May 1995.

33. Apfelbaum, S. I., J. D. Eppich, T. Price, and M. Sands, "The Prairie Crossing Project: Attaining Water Quality and Stormwater Management Goals in a Conservation Development," unpublished manuscript; S. I. Apfelbaum, J. D. Eppich, T. Price, M. Sands, D. Hoffman, and P. Margolin, "On Conservation Developments and Their Cumulative Impacts," unpublished manuscript.

34. See Prairie Crossing, Grayslake, Illinois case study in Chapter 10, p. 224.

35. A good reference for alternative parking arrangements is provided in chapter 7 of T. R. Schueler, Site Planning for Urban Stream Protection, Metropolitan Washington Council of Governments, December 1995.

36. Sorvig, K., "Porous Paving," Landscape Architecture, February 1993, vol. 83 no. 2, p. 66.

37. Traditional neighborhood developments are also known as neo-traditional developments or "new urbanist" developments; U.S. Environmental Protection Agency, Green Development: Literature Summary and Benefits Associated with Alternative Development Practices, EPA 841-B-97-001, September, 1996, pp.1113.

38. U.S. Department of Transportation, Our Nation's Travel: 1995 Early Results Report, Washington, DC, September 1997, p. 32.

39. Horner, R. R., J. J. Skupien, E. H. Livingston, and H. E. Shaver, Fundamentals of Urban Runoff Management: Technical and Institutional Issues, Terrene Institute, August 1994, p. 113.

40. Livingston, E. H., "Successful Stormwater Management: Selecting and Putting the Puzzle Pieces Together," Florida Department of Environmental Protection, Stormwater/Nonpoint Source Management Section, Tallahassee, Florida, 1997, p. 7.

41. Livingston, E. H., "Successful Stormwater Management: Selecting and Putting the Puzzle Pieces Together." Florida Department of Environmental Protection, Stormwater/Nonpoint Source Management Section, Tallahassee, Florida, 1997, p. 7.

42. NRDC has adapted this grouping from Watershed Management Institute, Handbook for the Operation, Maintenance and Management of Stormwater Systems, pp. 1-4 to 1-6.

43. Much of the information concerning detention practices presented here is taken from Watershed Management Institute, Handbook for the Operation, Maintenance and Management of Stormwater Systems, pp. 1-4 to 1-5.

44. Horner, R. R., J. J. Skupien, E. H. Livingston, and H. E. Shaver, Fundamentals of Urban Runoff Management: Technical and Institutional Issues, Terrene Institute, August 1994, pp. 119, 124.

45. Klein, R., Preventing Damage to 600 Miles of Maryland Streams, Wetlands, Rivers, and Tidal Waters: Why Improvements to Maryland's Stormwater Management Program are Urgently Needed, Community & Environmental Defense Services, Freeland, Maryland, 1999.

46. Retention basins generally have an emergency spillway to allow passage of very large stormwater flows, but these outlets are placed sufficiently high that water from routine rainfall cannot escape through them.

47. AbTech Industries of Scottsdale, Arizona, for example, has recently developed catchbasin inserts and passive skimmers for control of oil and other hydrocarbons using its proprietary petroleum-derived polymer material. AbTech Industries, Introducing OARSTM, promotional flyer, undated.

48. Dixon, K. R. and J. D. Florian, Jr., "Modeling Mobility and Effects of Contaminants in Wetlands." Environmental Toxicology and Chemistry, vol. 12, 1993, p. 2290; Stecker, E. W., J. M. Kershaw, E. D. Driscoll, and R.R. Horner, The Use of Wetlands for Controlling Stormwater Pollution, U.S. Environmental Protection Agency Region V and Terrene Institute, April 1992.

49. Zillioux, E. J., D. B. Porcella, and J. M. Benoit, "Mercury Cycling and Effects in Freshwater Wetland Ecosystems," Environmental Toxicology and Chemistry, vol. 12, 1993, p. 2245; Rudd, J. W. M., "Sources of Methyl Mercury to Freshwater Ecosystems: A Review." Water, Air, and Soil Pollution, vol. 80, 1995, pp. 697713.

50. Larry Walker Associates, NDMP Inlet/In-line Control Measure Study Report 199798. Sacramento Stormwater Monitoring Program, June 1998, p. 35; Interagency Catchbasin Insert Committee, Evaluation of Commercially-Available Catchbasin Inserts for the Treatment of Stormwater Runoff from Developed Sites, King County Surface Water Management Division, King County Department of Metropolitan Services, Snohomish County Surface Water Management Division, Seattle Drainage and Wastewater Utility, and Port of Seattle, October, 1995, pp. I- ii, 4345, 53; Woodward-Clyde Consultants, Parking Lot BMP Manual, Santa Clara Valley Nonpoint Source Pollution Control Program, June 1996, p. 30.

51. R. Klein, Preventing Damage to 600 Miles of Maryland Streams, Wetlands, Rivers, and Tidal Waters: Why Improvements to Maryland's Stormwater Management Program are Urgently Needed, Community and Environmental Defense Services, Freeland, Maryland, 1999.

52. Kentucky bluegrass lawns often cover up to 90 percent of a home's landscaping. Bluegrass requires approximately 25 to 30 inches of water each growing season. City of Fort Collins, "The Seven Principles of Xeriscape," 1997, www.ci.fort-collins.co.us/utilities/water/conserv/seven.htm.

53. The term xeriscaping was coined by a special task force of the Denver Water Department, Associated Landscape Contractors of Colorado, and Colorado State University to describe landscaping with water conservation as a major objective.

54. Denver, Colorado; Fort Collins, Colorado; Colorado Springs, Colorado; Austin, Texas; Albuquerque, New Mexico; Fort Lauderdale, Florida; Southwest Florida Water Management District; Cobb County, Georgia.

55. Arnold, C. L. and C. J. Gibbons, "Impervious Surface Coverage: The Emergence of a Key Environmental Indicator," Journal of the American Planning Association, vol. 62, No. 2, Spring 1996, pp. 249251.

56. See case study on Geauga County, Ohio and St. Joseph County, Indiana, p. 236.

57. One early example of such certification was the "Green Card" program developed by Richard Klein, Earl Shaver and others for the State of Maryland in the early 1980s. Many other communities and States, including Delaware, now employ some form of certification.

58. For instance, Montgomery County, Maryland worked with the local Sierra Club in the spring and summer of 1998 to enable citizens to turn a trained eye on construction sites and to report observations to the appropriate inspector.

59. Charlotte, North Carolina, for example.

60. In New Castle County, Delaware, compliant construction sites that sign up to the Delaware Nature Society's Soil Stewards program get to post a sign proclaiming their stewardship to the public.

61. Brown and Caraco, Center for Watershed Protection, Controlling Stormwater Runoff Discharges from Small Construction Sites: A National Review, Report to U.S. Environmental Protection Agency Office of Water, Center for Watershed Protection, Ellicott City, Maryland, 1997, p. II-I.

62. Kathleen, C., "Clearing and Grading Guidance: a guide to improving clearning and grading regulations through non-structural best management practices," Metropolitan Washington Council of Governments, Washington, D.C, 1994, cited in: Watershed Protection Techniques, vol.1, no.3, p. 141, Center for Watershed Protection, Ellicott City, Maryland.

63. Gere, J., Erosion Control Administer, City of Charlotte, North Carolina, personal communication, November 2, 1998.

64. Lozeau, M, San Francisco Bay Keeper, personal communication, October 14, 1998.

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