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2 Interstate Commission on the Potomac River Basin (ICPRB) ICPRB represents 5 states. Mission: enhance, protect and conserve the water and associated land resources of the Potomac River basin and its tributaries through regional and interstate cooperation.

3 ICPRB - Four major areas of interest Public information Water resources, quantity, and supply Water quality Living resources

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6 Potomac River Basin and the portion of the Washington metropolitan area served (in part) by the Potomac River

7 Washington area: three major water suppliers The three suppliers provide water to a total of 3.6 million people. These suppliers cooperate during droughts, pooling their resources to maximize water supply reliability.

8 Overview of study area and resources Occoquan River Patuxent River Potomac River Fairfax County Water Authority Washington Suburban Sanitary Commission Rockville DPW Washington Aqueduct COE Major Source CO-OP utility Wholesale or independent utility Key: District of Columbia Water and Sewer Authority Arlington County DPW Falls Church DPW Vienna DPW Prince William Service Authority Virginia American Water Co. Loudoun County Sanitation Authority

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11 Water supply intakes and portion of Potomac River protected by environmental flow recommendation.

’s forecast of Potomac shortages In times of low-flow, predicted demands are higher than flow. Implication: The COE, the most downstream water user, would run out of water if nothing were done.

13 Proposed structural solutions Series of 16 reservoirs Interbasin transfers Pilot estuarine treatment plant

14 LFAA No jurisdiction would suffer disproportionate shortages. Water rationed as a percentage of the normal wintertime water use.

15 Water Supply Coordination Agreement (1981) Mandates that suppliers coordinate operation of all facilities. Minimizes chances of a shortfall. Payment formula for future water supplies based on incremental growth ratios.

16 Little Seneca Jennings Randolph Potomac Basin and water supply reservoirs Occoquan Patuxent

17 Jennings Randolph Reservoir

18 Little Seneca Reservoir

19 Patuxent (Duckett) Reservoir

20 Occoquan Reservoir

21 Little Falls intake

22 Flow that would have occurred without a release Jennings Randolph release Target

23 Potomac flows and demands Higher flows Median flows Minimum flows Demands

24 Drought Management Issues Public response plan Media outreach and communications Practiced drought operations Utility and regional cooperation Planning for future demands

25 Drought website ( follow link for “Drought Exercise 2000”) Water supply status and key operational data are updated each day during droughts and for drought exercises including: –Reservoir storage, –River flow, –Precipitation forecasts, –Utility withdrawals, and –Daily summaries.

26 Today’s probability of meeting demand If the worst recorded drought were to occur this summer, the three major Washington metropolitan area suppliers would be able to meet water demands.

27 Tomorrow’s probability of meeting demand ICPRB continues to assess the reliability of the current water supply system for the Washington metropolitan area. The most recent study was completed in 2000 and is available at:

28 Benefits of regional cooperation Smooth operations during drought. Systems based operating strategies minimize possibility of shortfall. Stronger management and a unified voice. Trust in the procedures and institutions in place.