Precipitation Changes

The Effect on EPA Water Programs

Changes in the location, timing, form and amount of precipitation could have similar implications for water programs as do increases in air and water temperatures. In addition, in areas with increased precipitation, pollutant runoff might increase and stress stormwater conveyance systems and negatively affect water quality and drinking water quality. For example, decreases in precipitation might stress drinking water supplies and require water programs to reevaluate the location of their drinking water intake and implement water conservation planning.

In addition to several of the programs that were affected by increases in air and water temperature, stormwater, combined sewer overflows and underground injection control permits are anticipated to be affected by changes in the location, amount and intensity of precipitation.

Stormwater management systems might need to be designed to avoid being overwhelmed during intense rain storm events.

• Combined storm and sanitary sewer systems might need to be designed to avoid an increase of overflows and subsequent increased pollutant and pathogen loading resulting from untreated waste directly entering waterways.
• Increased monitoring efforts need to include biological monitoring and assessment techniques to assess the impact of higher water flow velocities.
• Watershed management techniques need to incorporate green techniques (e.g., green roofs) and smart growth to manage stormwater to reduce its velocity and to infiltrate water to replenish ground water instead of directly running off into storm drains and waterbodies.
• The importance of wetland management and buffers will increase as a method to control stormwater runoff.

Graphic Reference:
EPA. 2008cc. National Water Program Strategy: Response to Climate Change. EPA 800-R-08-001, accessed August 31, 2009.