Best Management Practices

Water Runoff from Flooding

Projects

Projects

Introduction
Environmental Issue or Problem
Background
Long-Term Goal and APGs Addressed
Status/Results
Expected Outcomes and Impacts
Contact

Introduction

Effective stormwater management is often achieved from a management systems approach, as opposed to an approach that focuses on individual practices. That is, the pollutant control achievable from any given management system is viewed as the sum of the parts, taking into account the range of effectiveness associated with each single practice, the costs of each practice, and the resulting overall cost and effectiveness. Some individual practices may not be very effective alone but, in combination with others, may provide a key function in highly effective systems.

Environmental Issue or Problem

The stormwater pollution problem has two main components: the increased volume and rate of runoff from impervious surfaces and the concentration of pollutants in the runoff. Both components are directly related to development in urban and urbanizing areas. Together, these components cause changes in hydrology and water quality that result in a variety of problems, including habitat modification and loss, increased flooding, decreased aquatic biological diversity, and increased sedimentation and erosion. Effective management of stormwater runoff offers a multitude of possible benefits, including protection of wetlands and aquatic ecosystems, improved quality of receiving water bodies, conservation of water resources, protection of public health, and flood control.

In addition to chemical pollutants in stormwater, the physical aspects related to urban runoff, such as erosion and scour, can significantly affect a receiving water's fish population and associated habitat. Alterations in hydraulic characteristics of streams receiving runoff include higher peak flow rates, increased frequency and duration of bankfull and subbankfull flows, increased occurrences of downstream flooding, and reduced baseflow levels. Traditional flood control measures that rely on the detention (storage) of the peak flow (referred to as peak shaving) have been characteristic of many stormwater management approaches, have generally not targeted pollutant reduction and in many cases have exacerbated the problems associated with changes in hydrology and hydraulics. EPA recommends an approach that integrates the control of stormwater peak flows and the protection of natural channels to sustain the physical and chemical properties of aquatic habitat.

Background

For much of human history, we disposed of that water with the idea that “dilution is the solution to pollution,” in that we got rid of it quickly enough and far enough away from human settlements, it would no longer be a problem. In cities and towns, we focused on sewers to transport and treat human or commercial waste, and storm sewers for the water that falls on our hard surfaces (i.e., those that don’t absorb water the way a native landscape of plants and soil normally do). In all cases, we have designed convenient ways to ferry water out of town and into the nearest water body where it will dilute and go away. Unfortunately, we have discovered that there is no “away” for stormwater and its pollutants.

Long-Term Goal and APGs Addressed

EPA Goal 2: Protecting America's Waters

Status and Results

Expected Outcomes and Impacts

Contact

Michelle Latham, Technology Transfer Specialist
Phone: 513-569-7601
Email: latham.michelle@epa.gov

U.S. EPA National Risk Management Research Laboratory
Andrew W. Breidenbach Environmental Research Center
Water Supply and Water Resources Division
26 West Martin Luther King Drive
Mail Code: MLK 693
Cincinnati, OH 45268