EPA Issues Report on Climate Change & Water

On Oct 2 the US Environmenal Protection Agency eleased  a strategy that outlines national actions to manage programs and invest resources to reduce adverse effects on water from climate change .  The full draft document can be found at: http://www.epa.gov/water/climatechange/.

The document’s executive summary outlines the following areas of concern with regards to water resources planning and management:

1. Increases in Water Pollution Problems: Warmer air temperatures will result in warmer water. Warmer waters will:
• hold less dissolved oxygen making instances of low oxygen levels and “hypoxia” (i.e., when dissolved oxygen declines to the point where aquatic species can no longer survive) more likely; and

• foster harmful algal blooms and change the toxicity of some pollutants.
The number of waters recognized as “impaired” is likely to increase, even if pollution
levels are stable.

2. More Extreme Water-Related Events: Heavier precipitation in tropical and inland storms will increase the risks of flooding, expand floodplains, increase the variability of streamflows (i.e., higher high flows and lower low flows), increase the velocity of water during high flow periods and increase erosion. These changes will have adverse effects on water quality and aquatic system health. For example, increases in intense rainfall result in more nutrients, pathogens, and toxins being washed into waterbodies.

3. Changes to the Availability of Drinking Water Supplies: In some parts of the country, droughts, changing patterns of precipitation and snowmelt, and increased water loss due to evaporation as a result of warmer air temperatures will result in changes to the availability of water for drinking and for use for agriculture and
industry. In other areas, sea level rise and salt water intrusion will have the same effect. Warmer air temperatures may also result in increased demands on community water supplies and the water needs for agriculture, industry, and energy production are likely to increase.

4. Waterbody Boundary Movement and Displacement: Rising sea levels will move ocean and estuarine shorelines by inundating lowlands, displacing wetlands, and altering the tidal range in rivers and bays. Changing water flow to lakes and streams, increased evaporation, and changed precipitation in some areas, will affect the size of wetlands and lakes. Water levels in the Great Lakes are expected to fall.

5. Changing Aquatic Biology: As waters become warmer, the aquatic life they now support will be replaced by other species better adapted to the warmer water (i.e., cold water fish will be replaced by warm water fish). This process, however, will occur at an uneven pace disrupting aquatic system health and allowing non-indigenous and/or invasive species to become established. In the long-term (i.e., 50 years), warmer water and changing flows may result in significant deterioration of aquatic ecosystem health in some areas.

6. Collective Impacts on Coastal Areas: Most areas of the United States will see several of the water-related effects of climate change, but coastal areas are likely to see multiple impacts of climate change. These impacts include sea level rise, increased damage from floods and storms, changes in drinking water supplies, and increasing temperature and acidification of the oceans.

These overlapping impacts of climate change make protecting water resources in coastal areas especially challenging.

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