Urban Land Use and Water Quality

Featured Study: Changes in influences that affect water quality

Featured Study: Changes in influences that affect water quality

Some of the major human influences on water quality—the ways we use land, water, and chemicals—have undergone dramatic changes over the last five decades. Patterns of urbanization, chemical use, and agricultural production are profoundly altered.

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Fish in urban streams provide a clue to mercury source

Fish in urban streams provide a clue to mercury source

Isotopes of mercury in fish can indicate the source of that mercury, reports a new USGS study. The groundbreaking study found that mercury in fish in urban and rural streams have different sources.

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Science Center Objects

Wherever you live, there’s a creek or stream near you. The eighty percent of Americans who live in metropolitan areas are often unaware of the network of urban creeks—many teeming with life—that weaves through our cities and town. Nowhere are the environmental changes associated with urban development more evident than in urban streams.

In urbanized areas, small streams are often overlooked or forgotten, but these streams can reduce contamination, ease flash flooding, and improve the esthetics and livability of our daily environment.

Contaminants, habitat destruction, and streamflow flashiness resulting from urban development disrupt biological communities, particularly sensitive aquatic species. Every stream is connected downstream to larger water bodies, including rivers, reservoirs, and ultimately coastal waters. Inputs of chemical contaminants or sediments at any point along the stream can cause degradation of water quality downstream, harming biological communities and economically valuable resources, such as fisheries and tourism.  It’s therefore important to know which urban-related stressors are most closely linked to biological community degradation, and how multiple stressors can be managed to protect stream health as a watershed becomes increasingly urbanized.

Water Quality and Ecology of Small Streams (RSQA)
The USGS Regional Stream Quality Assessment (RSQA) is studying the relations between stressors (chemical and physical) and stream ecology (fish, algae, and aquatic invertebrates) at hundreds of small streams across five major regions of the United States. Users can access an online mapping tool to compare water quality at small streams across a region, see scorecards that summarize stream health at each stream site, and download data for hundreds of chemical compounds.

Effects of Urban Development on Stream Ecosystems
In response to concerns about the degradation of urban streams, the USGS did a national-scale, scientific investigation of the effects of urban development on stream ecosystems.  A nationally consistent study design was used in nine metropolitan areas of the United States—Portland, Oregon; Salt Lake City, Utah; Birmingham, Alabama; Atlanta, Georgia; Raleigh, North Carolina; Boston, Massachusetts; Denver, Colorado; Dallas, Texas; and Milwaukee, Wisconsin. Read this comprehensive study of effects of urban development on stream ecosystems and learn about strategies for managing the effects of development.

Urban Land Use collection

Water quality, ecological sampling, and stream data collection at various urban streams in California, as part of the Regional Stream Quality Assessment.  (Credit: Dorene MacCoy and Barbara Mahler, USGS)

Streamflow Alteration
Humans, just like aquatic organisms, need water, but flood control, urban infrastructure, and myriad other ways we manage water affect the natural flow of streams and rivers. Learn how the ways we manage land and water affects the natural patterns of streamflow and the ecosystems that depend on them. 

Enoree River at Pelham Mill Dam, SC

Enoree River at the remains of the Pelham Mill Dam during summer flow (August 2012) and during flood conditions (April 2014)(left). The Pelham Mill site includes the remnants of a cotton mill and stonework dam (right).  (Credit: Peter Van Metre, USGS)

PAHs, Coal-Tar Sealcoat, and Environmental Health
A commonly used product in urban and suburban areas, coal-tar-based pavement sealcoat, is contributing to toxicity in streams. Coal-tar-based sealcoat, a potent source of polycyclic aromatic hydrocarbons (PAHs), is applied to many asphalt driveways and parking lots across much of the central, eastern, and southern U.S. Read about the toxicity of runoff and particles washed from coal-tar-sealcoated surfaces in a 6-page, color fact sheet

Urban Land Use and Groundwater Quality
The effects of our daily lives on groundwater quality are apparent in the concentrations of nitrate, pesticides, and other manmade chemicals found in shallow groundwater beneath urban and suburban land.  The USGS National Water Quality Assessment (NAWQA) Project characterized the quality of recently recharged groundwater in residential settings, typically with low to medium population densities (300 to 5,600 people per square mile). Read about the relations between urban land use and salinity, nitrate, pesticides, and volatile organic compounds in groundwater.

Lake and Reservoir Sediment Records the Effects of Urbanization
Many chemicals associated with urban and suburban activities—pesticides, PAHs, metals—adhere to sediment and are deposited at the bottoms of lakes and reservoirs. By collecting cores of sediment and analyzing if for chemicals in the oldest sediments at the bottom of the core to the most recently deposited sediments at the top, we can see how urbanization in the watershed has affected sediment quality through time.

PAH, Groundwater, and Coring Collage

(Left to right) Collecting PAH samples in an urban creek adjacent to coal-tar-based pavement sealcoat treated surfaces; Surficial aquifer groundwater sampling; Collecting lake sediment core at Town Lake in Austin, Texas.  (Credit: Barbara Mahler and Alan Cressler, USGS)

Interested in more water quality topics?
  ►  Learn about the effects of agriculture on stream quality