National Water-Quality Assessment (NAWQA) Project
Salt Lake City information sheet (2 pg PDF, 2.4 Mb)
This information sheet highlights selected findings of a comprehensive assessment by the National Water-Quality Assessment Program of the U.S. Geological Survey of the effects of urban development on stream ecosystems in nine metropolitan study areas. These are a few of the findings from the study in the Salt Lake City Metropolitan Area.
Prepared for November 30, 2012 Congressional briefing
Thirty sites were selected with drainage basin areas in the Central Basin and Range ecoregion portion of the basin between about 0.04 to 11.2 square miles (0.1 to 28.9 square kilometers). Some of the thirty sites were nested (more than one site on a stream) because there were only 13 streams in the region. The land use gradient went primarily from shrub or irrigated agriculture to urban. Sites represented a broad range of urban intensity from low to high.
Landcover, urban intensity, and site locations
Time of study:
Site selection in 1999.
Data collection from spring to early fall 2000.
The Salt Lake City study area is located in north-central Utah in the Western USA. The three largest cities in Utah are Salt Lake City, Provo, and Ogden. The population increased 24.4 percent from 1990 to 2000 in the Salt Lake City-Ogden Metropolitan Area and was about 1.33 million people in 2000 (U.S. Census Bureau, 2005).
These cities are along the western edge of the Wasatch Range, which rises from an elevation of about 4,202 feet (1,281 meters) above sea level at the valley floor to more than 11,483 feet (3,500 meters) in the mountains (Baskin and others, 2002). The study area is in the Central Basin and Range ecoregion (Omernik, 1994), which is characterized by xeric basins, scattered low and high mountains and salt flats.
Natural vegetation consists of sagebrush, saltbrush, and greasewood on dry alkaline soils, although vegetation in the urban areas is highly altered. Land use in the ecoregion is primarily irrigated agriculture and urban (Baskin and others, 2002).
The climate of the study area is semiarid, with mean an annual precipitation of 32 inches (82 centimeters) and a mean annual temperature of 41 degrees Fahrenheit (5.2 degrees Celsius)(Daymet, 2005). Summer months are typically dry, with precipitation occurring as thunderstorms (Baskin and others, 2002).
Highest streamflows occur in May and June from snowmelt, and lowest streamflow from October to March in the Wasatch Range (Baskin and others, 2002). Streams in the study area arise in the Wasatch Range and flow westerly through the urban areas. Typical of arid and semiarid urban areas in the Western USA, an array of reservoirs, diversions, and canals, alters the hydrologic regime of most streams in this region (Baskin and others, 2002). Streams in the study area support cool- and cold-water biological communities.
Giddings, E.M.G, Brown, L.R., Short, T.M. and Meador, M.R., 2006, Relation of fish communities to environmental conditions in urban streams of the Wasatch Front, Utah: Western North American Naturalist v. 66 p. 155-186.
For more information about the study area — http://ut.water.usgs.gov/nawqa/index.html