A River Ran Through It: How a Changing Climate is Impacting US River Systems

Did You Know?

  • Heavy downpours are increasing nationwide, especially over the last three to five decades. The largest increases have been in the Midwest and Northeast.
  • One in three Americans depend on seasonal or rain-dependent streams for drinking water.

A changing climate impacts the quality and quantity of water in US rivers. Observed and projected changes in precipitation intensity, groundwater runoff, flooding, fires, sea level rise, droughts, and seasonal conditions variably affect regional water resources and impact energy production, infrastructure, human health, agriculture, and ecosystems.

Northeast and Midwest: In the Northeast and Midwest, increases in heavy downpours can increase the amount of soil, nutrients, trash, animal waste, and other pollutants washed into rivers, making the water unusable, unsafe, or in need of treatment.

Coastal and Island Regions: In coastal and island regions, salt water can move into fresh water supplies due to sea level rise. The movement of saltwater upstream not only impacts the river ecosystem and its natural inhabitants, but may also jeopardize drinking water supplies, forcing water managers to find alternate sources of fresh water or to purchase equipment to remove the salt from the water.

Southwest and West: The Southwest and West have seen less rain and an increase in the severity and length of droughts over the past 50 years. With this trend expected to continue and intensify over the next century, the amount of fresh water available for recreation and drinking water will also decrease.

Northwest: The Northwest depends on melting snowpack to feed streams and rivers in the late spring and summer, when there is typically little rainfall in the region. Higher temperatures will threaten this natural storage and alter the timing of runoff and the amount of water available in streams and rivers – this water is needed to produce energy through hydroelectric power plants.

With the impacts from a changing climate threatening river water supplies, it is important to ensure that rivers and wetland areas are healthy enough to trap floodwaters, retain moisture during droughts, recharge groundwater supplies, filter pollution, and provide habitat for fish and wildlife.

Climate Change Impacts U.S. Water Systems

Sources:

  • Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W. Yohe, Eds. 2014. Climate Change Impacts in the United States: The Third National Climate Assessment. Washington: U.S. Global Change Research Program. http://nca2014.globalchange.gov/.
  • US EPA. 2016. "Climate Impacts in the Northwest." Accessed June 6. http://www3.epa.gov/climatechange/impacts/northwest.html
  • US EPA. 2016. "Climate Impacts on Water Resources." Accessed June 6. http://www3.epa.gov/climatechange/impacts/water.html
  • US EPA. 2016. "Why Clean Water Rules." Accessed June 6. http://www2.epa.gov/cleanwaterrule/why-clean-water-rules.
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