Seeking the best approaches for managing stormwater, communities nationwide are weighing the benefits of standard urban stormwater mitigation plans, stormwater utility districts, and other mechanisms. This article examines how SUSWMPs and SWUDs work and takes a close look at how the process is unfolding in one region of California - perhaps resulting in a draconian bureaucracy and enormous cost.

By S. Wayne Rosenbaum

Standard urban stormwater mitigation plans (SUSWMPs) and stormwater utility districts (SWUDs) are two of the means available for local and regional governments to manage stormwater programs. Each can encompass several different communities. Though not mutually exclusive, these two frameworks have some important differences in the autonomy and flexibility they offer the municipalities they include.
      The concept of the SUSWMP arises out of the Clean Water Act (CWA) 33 USC Section 1251, et seq. Congress enacted the CWA to "restore and maintain the chemical, physical, and biological integrity of the Nation’s waters." To achieve these goals, the act makes unlawful the discharge of any pollutant into surface waters except as authorized by specified sections of the act. One of those specified sections establishes the National Pollutant Discharge Elimination System (NPDES) permitting system.
      As part of an NPDES municipal permit, municipalities can be required to implement a stormwater mitigation plan (SWMP) as a means of minimizing the impacts on receiving waters resulting from continuing urbanization. Unfortunately, in some cases the specific terms of the SWMP amount to a very proscriptive model that may not allow municipalities the flexibility they need to identify, prioritize, and correct the most exigent problems.
      SWUDs are special assessment districts set up to generate funding for, and manage stormwater quality within, their geographic boundaries. Users within the district pay a stormwater fee, and the revenue generated supports the stormwater program.
      When organized on a watershed-by-watershed basis, SWUDs are big enough to have a reasonable chance of achieving water-quality standards but not so big as to become bureaucratic monsters. Nationwide, more than 400 communities have chosen SWUDs as the fairest, most cost-effective method to achieve water-quality standards.
      Because of their watershed perspective, SWUDs can effectively develop programs and allocate resources across municipal boundaries to achieve water-quality objectives throughout a watershed. SWUDs can efficiently identify and standardize best management practices (BMPs) to achieve those objectives in the most effective and efficient manner. Through their fee assessment authority, SWUDs can fairly allocate the cost of BMPs across all landowners in the watershed based on pollutant contribution. For a discussion of fee allocation, see "The Stormwater Utility: Will It Work in Your Community?" in the November/December 2000 issue of Stormwater.
      SWUDs do not replace SUSWMPs; rather, SWUDs allow stakeholders within a watershed to develop SUSWMPs designed to meet the specific needs of that watershed. By bringing the rulemaking down to a level that is understandable to those on whom the rules will be enforced, the SWUD allows for consensus-building among all stakeholders. This grassroots approach makes it easier to obtain the cooperation necessary to achieve the goals.
      The SUSWMP potentially exposes municipalities to significant new and conflicting land-use regulations. For example, the SUSWMP might suggest that developers significantly reduce the width of streets and driveways to increase infiltration. This solution, however, flies in the face of local ordinances requiring wider streets for emergency vehicles.
      SWUDs impact municipalities’ land-use authority as well. Because watersheds cross jurisdictional boundaries, the municipalities will have to cede rule-making authority to these multijurisdictional creatures. Because SWUDs operate on a watershed level, however, there is a greater potential to customize the mitigation plan to the community.

Effects of the SUSWMP and the SWUD

To understand the practical differences between SUSWMPs and SWUDs, it is helpful to look at the advantages and disadvantages of each for a particular community. Both of these models are under consideration in southern California.
      As the cartoon character Pogo said, "We have met the enemy and he is us." There is no question that increased population growth in southern California has led to significant degradation of stormwater quality. This is a trend that all agree must be stemmed and reversed. It is futile to try to shift the responsibility. Each person who lives in a watershed is part of the problem. The only question is how each can participate in the solution.
      On January 26, 2000, in a well-intentioned but misguided effort to improve water quality, the Los Angeles Regional Water Quality Control Board imposed the LA SUSWMP on 85 incorporated cities within Los Angeles County and on the county itself. A number of cities and other organizations submitted petitions for review of the SUSWMP to the State Water Resources Control Board, and the state board held hearings in June. On October 5 the state board ratified the LA SUSWMP, which will go into effect on February 15, 2001.
      On February 25, 2000, the San Diego Regional Water Quality Control Board announced that it would follow the LA Board’s lead and adopt an SUSWMP for San Diego County and its municipalities. On October 11, 2000, the SD Board issued the Draft Municipal Permit for Discharges of Urban Runoff From Municipal Separate Storm Sewer Systems (Tentative Order No. 2001-01). Included in this draft permit is an SUSWMP.
      After several workshops and the appeal of the LA SUSWMP, the SD Board determined that it would be prudent to delay adopting the SD SUSWMP until after the state board and the LA Board acted on the LA SUSWMP appeal. Currently it is expected that the SD Board will adopt the SD SUSWMP during the first quarter of 2001. Because the SD SUSWMP is essentially identical to the proposed LA SUSWMP, this article considers them together, with important differences noted.
      Questions abound regarding the SUSWMP’s potential to decrease the degradation of stormwater quality. While some stakeholders believe the SUSWMP approach is a necessary step toward regulatory compliance with the CWA and better water quality, others see it as an ill-considered urban and social engineering experiment with little or no chance of improving water quality. Meanwhile, other communities have taken a regional or watershed approach, identifying water-quality problems within their watersheds and then using their regional planning and fee authority to resolve those problems. Although stormwater utilities are increasing in number as planning and funding sources, some are still having difficulty convincing users that they are worth the cost.

Who Is Regulated Under the SUSWMPs?

Although this article focuses on the Los Angeles and San Diego SUSWMPs’ regulatory authority on new construction and reconstruction, the San Diego plan also regulates existing residential, commercial, and industrial development. The Los Angeles SUSWMP regulates six land-use categories:

1. residential subdivisions with 10 or more units
2. all single-family hillside residences
3. all 100,000-ft.² commercial developments
4. all automotive repair shops
5. all restaurants
6. all parking lots having 5,000 ft.² or more

The SD SUSWMP also includes retail gasoline outlets and any street, road, or highway.

To make sure that the SUSWMPs leave no one out, the Los Angeles and San Diego Boards added geographic criteria, declaring that the SUSWMPs apply to all development adjacent or discharging to an environmentally sensitive area (ESA). Although the state board struck this provision in the current LA SUSWMP, it did so for procedural reasons and invited the LA Board to reinsert the ESA provision in any future municipal permit. The SD Board staff retained this provision in the SD SUSWMP, believing there are no procedural bars to its inclusion in a new municipal permit.

What Do the SUSWMPs Require?

The SUSWMPs enforce three types of requirements on all regulated activities. First, the SUSWMPs impose seven specific design criteria for all development or redevelopment. These include limiting postdevelopment peak stormwater runoff discharges to predevelopment rates, minimizing "to the maximum extent practicable" stormwater runoff containing "pollutants of concern," including BMPs to minimize siltation, stenciling storm drains to discourage illegal dumping, prohibiting outdoor storage areas, requiring special containment for all trash containers, and transferring the SUSWMP obligation to future property owners through legally enforceable maintenance and repair agreements, funding guarantees, and other means. Second, the SUSWMPs impose additional specific requirements for some categories such as restaurants, gas stations and auto repair shops, and commercial developments over 100,000 ft.² Finally, and of most concern, the SUSWMPs require development and redevelopment projects to capture and mitigate (treat or "infiltrate") stormwater. The SUSWMPs require that, as part of its BMPs, each affected development or redevelopment shall infiltrate or treat all potential runoff produced from each and every storm event up to and including 0.75 in. (0.60 in. in the San Diego SUSWMP) of rainfall prior to its discharge to a stormwater conveyance system.
      The SUSWMPs define infiltration as the downward entry of water into the surface of the soil. Infiltration requires engineering designs that slowly discharge stormwater to the ground during the wettest season of the year. Infiltration is not an option for many projects and may require additional permits.
      How much water will the design need to handle? For 1 ac. of land, a 0.75-in. rainfall generates about 20,000 gal. or 2.5 gasoline tank trucks of water. Anyone who has had experience with a septic system will attest to the daunting challenge of this much water. Assuming the most benign soil percolation characteristics and weather conditions, it is likely that large-scale infiltration systems will include expensive, energy-intensive capture and storage systems to hold the water before it is pumped or gravity fed to huge leach fields. This is particularly true for San Diego County, where it is estimated that less than 20% of the soils have any infiltration capacity.
      Additionally, the regional boards have limited infiltration to land uses and locations that will not impact groundwater quality. Although this is an admirable goal, in most urban areas this will require treatment before infiltration. The cost of treatment is unknown and will depend on the definition of "pollutants of concern" and the water quality required. If treatment consists simply of good housekeeping or particulate removal, costs should be tolerable. The effect on water quality will be negligible, however. If treatment consists of removing all pollutants to the parts-per-billion level, the cost will escalate rapidly.

Effects on Development

The SUSWMPs require that affected projects contain and infiltrate or treat 85% of the rain that falls in San Diego and Los Angeles Counties. The California Storm Water Quality Task Force and the California Department of Transportation estimate the cost of building such systems, on a statewide basis, at more than $14 billion. This is an expenditure of more than $500 for every Californian, and this cost estimate does not include maintenance. Unfortunately, the SUSWMPs do not spread that cost evenly over all of society; rather, it burdens newcomers and those who would rejuvenate the urban core.
      In contrast, an SWUD’s ability to impose a user fee on all property owners makes the process more equitable and economical for all property owners in the watershed. Equity in burden sharing will go a long way toward obtaining consensus on water quality as a high-priority goal.

Effects on the Urban Core

Consider a proposed commercial redevelopment of a shopping center in a blighted inland urban area. The center’s stormwater discharges, eventually, to San Pedro Bay, where the sediments contain elevated levels of copper. Copper has the potential to bioaccumulate in shellfish. Copper comes from brake dust left by cars that will use the center’s parking lot and thus will likely be present in stormwater runoff from the parking lot.
      Because of the high cost of land in the urban area, lower-cost solutions such as infiltration are not viable. For the center to treat the stormwater to remove the copper is possible in theory but prohibitively expensive. Removal requires the same technologies that the computer-chip industry uses to make ultrapure water. Will shoppers be willing to pay higher prices for their food to remove trace amounts of copper from their stormwater? Alternatively, will they simply shop somewhere else and avoid this new surtax? Can poor urban-area families who might not be able to shop elsewhere unilaterally afford the financial burden of better water quality?
      Alternatively, SWUDs provide a regional solution. Here it might be more appropriate for the commercial redevelopment to implement nonstructural pollution prevention practices, such as more frequent sweeping of the parking lot, while the SWUD uses its resources to build a constructed wetland to help reduce heavy metal contaminants in all of the upstream runoff. This model encourages urban redevelopment while using community resources to achieve the best water-quality results.

Effect on the Legal System

SUSWMPs are prescriptive in nature and, therefore, require a litany of definitions. But because they are intended to affect a broad geographic area, many of those definitions are missing, vague, or ambiguous. As such, SUSWMPs are an invitation to a lawsuit. What is certain is that the SUSWMP is enforceable under the citizen suit provision of the CWA, thereby exposing the developer, property owner, and municipality to significant legal liability.
      An SWUD has the authority to create the customized rules and regulations necessary to achieve water quality within its area of jurisdiction. It is not subject to the broad mandates of a "one-size-fits-all" plan intended to improve water quality for an entire region.

Effect on the Environment

SUSWMPs attempt to plan for water quality on a grand scale. The major thrust of this planning is to require the capture and treatment or infiltration of all stormwater in southern California. State and federal technical guidance extols infiltration as the favorable solution. However, infiltration raises many troubling, unanswered questions. In addition to the engineering and regulatory issues previously discussed, there are significant unsolved environmental issues. Can the soils absorb massive quantities of stormwater without causing subsidence or slippage? Without these stormwater flows, will sensitive environmental areas, such as wetlands, simply dry up? If the stormwater is not pure enough for discharge to local streams and beaches, what effect will it have on underground water supplies?
      SWUDs allow for water-quality planning on a more human scale, one watershed at a time. By planning at this level there is a better opportunity to consider and avoid the negative unanticipated consequences of large-scale environmental and social engineering.

Effects on the TMDL Process

Even as the regional boards adopt SUSWMPs, the very same agencies are working to set measurable, scientifically defensible water-quality standards called total maximum daily loads (TMDLs). TMDLs provide a rational basis for determining "pollutants of concern" and "maximum extent practicable." Simply stated, a pollutant of concern is a pollutant that exceeds the TMDL for the respective receiving water.
      Using TMDLs, we can allocate pollutant loads on a rational basis within a watershed. TMDLs can be effectively integrated into stormwater management plans only if comparable geographical scales are applied. For this reason, the watershed SWUD seems to be a better long-range planning tool.

How the SWUD Model Might Work

The San Diego Regional Water Board regulates the San Diego Basin, which consists of nine watersheds. Most of the watersheds encompass portions of several municipalities. Each watershed could form an SWUD with a board representing the affected municipalities and other stakeholders. Each SWUD would then implement its own SUSWMP as follows.
      Initially all development or redevelopment would be subject to the SUSWMP as proposed by the regional board. Where an SWUD is formed, however, any project could choose to implement the SUSWMP either individually or through the SWUD. If the project chose to work with the SWUD, then it would pay a waiver fee to the SWUD, probably about 1-2% of the total project cost. The SWUD would then use these funds to develop TMDLs for the watershed and design BMPs sufficient enough to ensure that stormwater did not exceed its TMDL allocation. BMPs could include anything from more frequent street sweeping and better public awareness to development of infiltration ponds, constructed wetlands, and biofilters. Using its fee assessment authority, the SWUD would then assess all property owners pro rata based on the amount of impervious area they owned. The fees would be used exclusively to build and maintain the BMPs.
      In this model, property owners are financially encouraged to reduce impervious area because it reduces their SWUD fees. SWUDs are better positioned to develop rational BMPs based on the water-quality objectives of each watershed. Everyone participates in the solution, which is only fair because everyone is part of the problem. Finally, this plan has a better chance of being successful both technically and politically.

Conclusions

The SUSWMP model, as it is being adopted in southern California, is out of scale. It will create a draconian bureaucracy and monumental cost. The SUSWMP will not improve water quality over any reasonable period because it does nothing to improve stormwater quality at the human level. The SWUD is a socially and technically viable delivery system that can improve water quality in a faster, cheaper, and fairer manner.
      SUSWMPs as currently envisioned in southern California are not the solution to better water quality. Watershed management programs, such as the SWUDs that develop TMDLs to rationally regulate water quality by helping to define the best and most efficient BMPs, can work. Water-quality agencies should, on reconsideration, revise the SUSWMP to encourage SWUDs.

S. Wayne Rosenbaum is an attorney with the San Diego office of McKenna & Cuneo. His practice centers on environmental issues including the development of cost-effective compliance strategies for municipalities and industries regulated under the stormwater provisions of the Clean Water Act.