1. 1 Supplying Water in an Uncertain Future: Including Issues of Water Resources, Wastewater Treatment, and Stormwater Management Roland Steiner Washington Suburban Sanitary Commission AMS Policy Forum on Water Resources March 26 – 27, 2008

2. 2 Planning, then operations, and protection Water Supply Water SupplyDemandsResources Wastewater Wastewater Stormwater Management Stormwater Management

3. 3 Uncertainty in Water Supply planning level demand forecasting – usually based primarily on population forecasts

4. 4

5. 5 However, there is considerable uncertainty and error in population forecasts. Thus the water demand forecasts turn out to be rather inaccurate. However, there is considerable uncertainty and error in population forecasts. Thus the water demand forecasts turn out to be rather inaccurate.

6. 6 Historical forecast perspective

7. 7 In any case forecasts have to be made in order to plan capital project sizing and scheduling. In any case forecasts have to be made in order to plan capital project sizing and scheduling.

8. 8

9. 9 Water demand: Recent trends Production similar between 1990-1999 and 2000-2004 Low winter c. 400 MGDLow winter c. 400 MGD Summer c. 550 MGDSummer c. 550 MGD Drought demands significantly higher  link of demand to weather variables

10. 10

11. 11 In wet years and dry ones, there are competitive demands for water resources. In wet years and dry ones, there are competitive demands for water resources.

12. 12 Mirant Power Plant, Dickerson, MD

13. 13 Combine water demands with water resources and their operations. Combine water demands with water resources and their operations.

14. 14

15. 15 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

16. 16

17. 17 Combined use of River flow and reservoir storage. Combined use of River flow and reservoir storage.

18. 18 Potomac River Flow upstream of water supply intakes, 1930 Historical Drought vs. a Synthetic Drought (reservoir releases are not included)

19. 19 Little Seneca Reservoir

20. 20 JENNINGS RANDOLPH LAKE

21. 21 T. Howard Duckett Dam

22. 22

23. 23 Reservoir refill is as, or more, important than withdrawals

24. 24

25. 25 Patuxent Storage 2001 - 2002

26. 26 Competition for reservoir storage and releases Competition for reservoir storage and releases

27. 27 Reservoir Storage Types Outlet Works Inactive Storage Water Quality Storage Water Supply Storage Spillway Total Usable Storage Flood Control Storage Conservation Storage

28. 28 Streamflow vs Suspended Sediment

29. 29 Sedimentation Effects Inactive Storage Water Quality Storage Water Supply Storage Flood Control Storage

30. 30

31. 31

32. 32 Wastewater Facilities:- It all Starts Here

33. 33 And with too much rain, it ends here

34. 34 Increased rainfall intensity worsens sewer overflows and flooding

35. 35 Blue Plains AWWTP

36. 36 Rising sea level could affect discharges to tidal waters

37. 37 Increased rainfall intensity challenges stormwater management

38. 38 Water and wastewater treatment facilities are vulnerable to flooding

39. 39

40. 40 Treatment plants are out there somewhere

41. 41

42. 42 Brighton Dam – all gates open

43. 43 Reinforcement of Loch Raven Dam, Baltimore

44. 44 For a relatively small dam, a high cost job

45. 45 Possible Climate Change Impact on Rainfall Distribution