New USGS Water-Quality Findings - Altered Streamflows Leading to Degraded River Ecosystems across U.S.

New USGS findings released in the journal of Ecological Society of America, Frontiers in Ecology and the Environment,accessible at: http://www.esajournals.org/doi/abs/10.1890/100053

Most River Flows across the U.S. are Altered by Land and Water Management, Leading to Ecological Degradation—This USGS assessment provides the most geographically extensive analysis to date of streamflow alteration. Findings show that the amount of water flowing in streams and rivers has been significantly altered from land and water management in nearly 90 percent of waters that were assessed in the nationwide USGS study. Flow alterations are a primary contributor to degraded river ecosystems and loss of native species whose survival and reproduction are tightly linked to specific flow conditions. These consequences can also affect water quality, recreational opportunities and the maintenance of sport fish populations.

Flows are altered by a variety of land- and water-management activities, including reservoirs, diversions, subsurface tile drains, groundwater withdrawals, wastewater inputs, and impervious surfaces, such as parking lots, sidewalks and roads.

The severity and type of stream flow alteration varies among regions, due to natural landscape features, land practices, degree of development, and water demand. Differences are especially large between arid and wet climates. In wet climates, watershed management is often focused on flood control, which can result in lower maximum flows and higher minimum flows. Extremely low flows are the greatest concern in arid climates, in large part due to groundwater withdrawals and high water use for irrigation.

Contact: Daren Carlisle, 703-648-6890, dcarlisle@usgs.gov