U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2012–3079

June 2012

Effects of Urban Stormwater-Management Strategies on 

Stream-Water Quantity and Quality

Printed on recycled paper

Introduction

Urbanization results in elevated 

stormwater runoff, greater and more 

intense streamflow, and increased 

delivery of pollutants to local streams 

and downstream aquatic systems such as 

the Chesapeake Bay. Stormwater Best 

Management Practices (BMPs) are used 

to mitigate these effects of urban land use 

by retaining large volumes of stormwater 

runoff (water quantity) and removing 

pollutants in the runoff (water quality).

What is a BMP?

Structural stormwater BMPs are 

constructed in urban areas to mitigate 

both water-quantity and water-quality 

issues caused by stormwater runoff 

(fig. 1). These BMPs can be placed in the 

stream or on land both above and below 

the surface. One goal of stormwater 

BMPs is to detain large volumes of water 

to prevent urban flooding and erosion of 

stream channels. Stormwater BMPs used 

to mitigate these water-quantity issues 

can include retention ponds, detention 

ponds, wetlands, infiltration trenches, and 

underground storage tanks. Another goal 

of stormwater BMPs is to provide waterquality treatment of stormwater runoff 

to remove pollutants such as sediment, 

phosphorus, nitrogen, oils, metals, and 

trash. Stormwater BMPs providing waterquality treatment can include bioretention 

cells, wetlands, sand filters for sediment, 

storm filters for nutrients, and oil and 

grease separators. Some of these BMPs 

Figure 1. Examples of stormwater Best Management Practices commonly used in urban areas to mitigate stormwater runoff: (A) stormwater 

wetland, (B) retention (wet) pond, (C) sand filter in series with a detention (dry) pond, (D) oil and grit separator, (E) bioretention cell, (F) grassed 

swale, (G) underground storm filter, (H) underground detention and filtration units (shown during installation), (I) rain barrel, and (J) rain garden.

A

I

B C

D E F

G H J
(including wetlands and detention ponds) 

can provide treatment in both waterquantity and water-quality capacities. In 

addition to structural BMPs, nonstructural BMPs, such as streetsweeping and 

public education, are also effectively used 

to prevent urban pollutants from reaching 

streams, rivers, and lakes. What remains 

elusive, however, is knowledge of how 

the distribution and connectivity (that is, 

the strategy) of these BMPs in a watershed influences their ability to mitigate 

large volumes of stormwater runoff and 

reduce pollutant transport.

Ongoing Research at USGS

At the U.S. Geological Survey 

(USGS), researchers in the Eastern 

Geographic Science Center are studying 

how the spatial pattern and connectivity 

of stormwater BMPs affect water 

quantity and water quality in urban 

areas. Traditionally, stormwater BMPs 

have been implemented in a centralized 

manner with BMPs typically located in 

the stream channel or directly adjacent to 

the stream (fig. 2). This is in contrast to 

recent trends of implementing BMPs on 

the landscape and in a distributed manner 

with the goal of treating and retaining 

stormwater runoff at its source. Research 

at the USGS is designed to improve 

understanding of how centralized and 

distributed BMPs differ in their ability to 

control stormwater and pollutant export 

from urban watersheds during storm 

events.

To address this question, monitoring 

is being conducted in the Clarksburg 

Special Protection Area in Montgomery 

County, Maryland, and in the Difficult 

Run Watershed in Fairfax County, 

Virginia, in partnership with county, 

academic, and other Federal agency 

scientists. Supporting geospatial analyses 

include land use/land cover (LULC) 

mapping, topographic feature analyses, 

and creation of stormwater BMP databases. Field monitoring includes analysis 

of stream samples collected during storm 

events, continuous monitoring of streamwater quality using in situ sensors, and 

monitoring of precipitation. 

Data collected as part of this 

research enables an understanding 

of how centralized and distributed 

stormwater BMP strategies and LULC 

affect watershed hydrology and pollutant 

transport. For example, stream-discharge 

data indicate how contrasting stormwater 

BMP strategies affect the duration of 

peak discharge during a storm event and 

the export of water after a storm event 

occurs (fig. 3). Stream-chemistry and 

sediment data can reveal how effective 

these stormwater BMPs are in reducing 

urban-pollutant export. Detailed and 

comprehensive LULC, elevation, 

and BMP databases are essential for 

understanding and quantifying spatial 

differences in development patterns 

and stormwater-management strategy 

implementation.

Application

Results from this research provide 

valuable information to resource managers and regulators on effective ways 

that stormwater BMPs may be used to 

mitigate water-quantity and water-quality 

consequences of urban LULC. Reduction 

of high-velocity streamflow during 

storm events by stormwater BMPs 

could enable more stable streambanks, 

resulting in less erosion and more robust 

stream ecology. Identification of effective 

stormwater-management strategies may 

help reduce nutrient and pollutant export 

from urban areas, thereby protecting local 

streams and downstream systems like the 

Chesapeake Bay, resulting in healthier 

and more sustainable aquatic systems. 

For additional information, 

please contact:

Dianna M. Hogan

U.S. Geological Survey

521 National Center

12201 Sunrise Valley Drive

Reston, VA 20192

Telephone: (703) 648–7240

Email: dhogan@usgs.gov 

J.V. Loperfido

U.S. Geological Survey

521 National Center

12201 Sunrise Valley Drive

Reston, VA 20192

Telephone: (703) 648–5134

Email: jloperfido@usgs.gov

Or visit the USGS Eastern Geographic 

Science Center at http://egsc.usgs.gov.

Figure 2. Comparison of contrasting 

stormwater-management strategies. 

Centralized Best Management Practices 

(BMPs) are often located in the stream 

channel or directly adjacent to the 

stream, whereas distributed BMPs are 

dispersed throughout the watershed on 

the landscape and can provide stormwater 

treatment in series. Typically, centralized 

BMPs are designed to treat much larger 

drainage areas compared to distributed 

BMPs. Differently shaped distributed 

BMPs represent the variety of treatment 

processes shown in figure 1.

Figure 3. Important differences in stream discharge from watersheds with contrasting 

stormwater-management strategies include broader peaks during stormflow in the 

watershed with centralized Best Management Practices (BMPs) and higher stream 

baseflow following stormflow in the watershed with distributed BMPs (data source 

http://nwis.waterdata.usgs.gov/nwis).

Centralized BMPs Distributed BMPs

Broader stormflow

peaks in centralized

BMPs watershed

Higher baseflow

following stormflow

in distributed BMPs

watershed

Distributed BMPs

Centralized BMPs

1.00

0.10

0.01

Instantaneous specific discharge,

in cubic meters per second per square kilometer

18:00 24:00 6:00 12:00 18:00 24:00 6:00

Hour