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Volume 4, Number 4
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A Stormwater Primer

By Jack Greer


two pie charts showing sources of nitrogen and phosphorus in Ann Arundel County waters 2002 - Chesapeake Bay Program

Stormwater dwarfs agriculture as the major source of nutrients in developing areas like Anne Arundel County, Maryland. Increasing levels of stormwater will require enforcement of current regulations and more funding, probably through new fees. Source: Chesapeake Bay Program.

Erosion and sediment control. The Maryland Department of the Environment has authority over sediment control statewide, but it also delegates authority to counties and municipalities to administer and enforce their own sediment control programs.

A developer must submit a comprehensive erosion and sediment control plan to comply with both Maryland and federal regulations. Maryland's sediment control regulations are more rigorous than those set forth in the federal Clean Water Act — though violators can face federal as well as state penalties.

According to the Maryland Department of the Environment, the state's sediment and control laws face several limitations. They call for general construction requirements, but do not contain specific standards for pollution prevention or removal. They are designed to handle runoff from smaller storms. According to MDE, "A site that meets all ESC [erosion and sediment control] standards may still contribute a significant amount of sediment to the Bay and its tributaries," especially during larger storm events.

Stormwater regulations. Stormwater controls go beyond controlling erosion and focus on controlling the flow of water from developed lands. Maryland has statewide stormwater requirements in the Code of Maryland Regulations, and in 2000, the state adopted a new Stormwater Design Manual. All counties and municipalities must incorporate the new state requirements into local ordinances.

Maryland's stormwater manual includes guidelines for managing flow during small to large storm events. The manual emphasizes the need to maintain as much as possible flow rates similar to those preceding development. The entire manual in two volumes is available from the Maryland Department of the Environment (on the web at www.mde.state.md.us).

Paying for Stormwater



Bioretention. This method uses carefully selected plants, substrate, and design to slow stormwater and take up nutrients. According to the Nationwide Pollutant Removal Performance Database for Stormwater Treatment Practices, a conventional shallow detention pond or wetland removes 39 percent of phosphorus while bioretention removes 65 percent. Bioretention can also sequester heavy metals and other toxic compounds.

Erosion and sediment control. In 1970 Maryland was one of the first in the country to pass a sediment control law. This law requires a permit from the soil conservation district before construction, and focuses on preventing the runoff of soil and sediment. The law is fairly general, however, and specific implementation occurs at the local level.

Combined sewer systems. Often found in older urban areas like Baltimore and Washington and known as combined sewer overflow (CSO), these combined systems send stormwater and municipal sewage to a waste treatment plant through a network of shared pipes. Rain events can quickly increase volume and challenge a plant's treatment capacity.

Separate stormwater systems. These systems handle stormwater and sewerage in two separate systems. The shorthand term for these municipal separate storm sewer systems (MSSSS) is MS4. These separate storm sewer systems are permitted differently from combined sewer systems.

NPDES. The National Pollutant Discharge Elimination System was established in 1972 under the authority of the federal Clean Water Act. In terms of stormwater controls, NPDES permits took effect in two phases, referred to as Phase I and Phase II.

Phase I. The first phase of NPDES, established in 1990, requires stormwater permits for municipalities with populations of 100,000 or more.

Phase II. The second phase of NPDES, established in 1999, extends permit requirements to smaller municipalities (generally with populations of 10,000 or more) with separate stormwater systems (MS4s) and smaller construction sites (e.g., one acre or more).

According to Dan Nees, director of the University of Maryland Environmental Finance Center, stormwater is about two things: "Fixing the sins of the past, and preventing future sins."

The sins of the past include everything from poorly planned parking lots to large ultra-urban environments, such as Washington and Baltimore. The Chesapeake Bay Blue Ribbon Finance Panel, chaired by former Virginia governor Gerald L. Baliles, determined that it would cost about $15 billion to address stormwater problems throughout the watershed. About 60 percent of that figure, or $9 billion, would go to retrofitting stormwater management facilities in already developed areas.

A special problem in older cities is combined sewer overflow, where sewerage headed for a treatment plant mixes with stormwater in a system of shared pipes. Estimates for repairing this problem in Washington and Baltimore approach $1 billion for each city.

While the EPA has listed urban stormwater as one of the top degraders of the nation's estuaries, the problem may not rise to the top of a municipality's priority list. For this reason Nees says that we should focus on increasing the capacity of local communities. "We shouldn't just think of this as a Bay problem. We should think of it as a community problem," he says.

Even at the state level, agencies often lack the capacity to handle and inspect all the permits called for by the federal Clean Water Act and its National Pollutant Discharge Elimination System (see Glossary).

The laws are essentially there, Nees says, but we lack the capacity to enforce them.

One solution, he says, is to create a reliable source of funds at the local level, a dedicated fund set aside specifically for stormwater that cannot be raided for other uses. One model established by a number of municipalities, including Virginia Beach, Virginia, and Montgomery County, Maryland, is to set up a stormwater utility. This approach calls for citizens to pay a stormwater bill, just as they would any other utility, though it is usually modest — for example $5 a month in Virginia Beach. The proceeds are then placed in a dedicated fund and used to implement stormwater management efforts on the ground.

Nees says that the best approach is for communities to focus on not creating stormwater problems to begin with, and to develop the right best management practices (BMPs) such as low impact development (LID) and the right financial tools (e.g., a stormwater utility).

"It is much cheaper to prevent problems than to have to fix them," he says.

For more information about financing watershed protection visit the Environmental Finance Center at www.efc.umd.edu.

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