Nonpoint Source Contaminants Research
Reducing Toxic Pollutant Concentrations in Urban Runoff

Background

Toxic pollutants in urban runoff contaminate many water bodies in Wisconsin cities. Wisconsin's Nonpoint Source Program has established large toxic pollutant reduction goals for many of the cities in priority watershed projects. Construction of detention ponds is the management alternative most commonly recommended for established urban areas. Unfortunately, the benefits can be offset by the high cost of building them in established urban areas.

The construction of many ponds would also require removing existing structures, possibly generating local resistance. Furthermore, detention basins offer limited control of some pollutants. The concentration of many dissolved pollutants, such as chloride and diazinon, are not reduced in a pond. Other pollutants, such as copper and zinc, might experience a large reduction in loading, but still exceed the acute toxicity criteria for warm water fisheries at the outlet. Large maintenance cost to insure the best possible functioning of hundreds of ponds presents further problems.

The above issues make it difficult to promote detention ponds as the primary method of achieving pollutant reduction goals in established urban areas. Methods of complementing the use of detention ponds, such as street sweeping, are discussed in the priority watershed plans. However, faced with such large reduction goals in toxic pollutant loading, the most promising alternative might involve more innovative practices.

One type of innovative practice is to install on-site structural practices at critical source areas. On-site practices can do a better job of targeting the source of the pollutants than a detention pond. They can be installed underground to minimize disruption at the property. Additional testing of the devices is needed to establish them as a cost-effective urban best management practice.

The work will be conducted by the US Geological Survey, an Engineering Consulting Firm, and the University of Wisconsin Extension through a contract with the DNR.

Objectives

To achieve the toxic pollutant reduction goals of Wisconsin's Nonpoint Source program by implementing cost-effective best management practices in established urban areas.

Benefits

The proposed project will aid the Nonpoint Source Program's efforts to establish cost-effective practices in Wisconsin cities. Also benefiting from this project are other environmental programs that address reducing toxic pollutant loadings to water bodies around urban areas, especially in the Great Lakes Basin.

For more information on this topic, please contact:
Steve Greb (608) 221-6362