problem of supplying water to the 

 Washington Metropolitan Area. This 

 area is already water short, and 

 should we have another drought, 

 there could be problems. 



My co-workers at the Baltimore 

 District are currently conducting a 

 study oriented to solving this water 

 supply problem. One thing is clear. 

 There are a lot of alternatives. An 

 important one of these is a proposal 

 to use Potomac Estuary at Washington 

 as a supplemental water supply 

 source. There are, however, some 

 questions regarding this proposal. 

 First, although the water at the lo- 

 cation where an intake is being con- 

 sidered is normally fresh, the salt 

 wedge intruded to within several 

 miles of it during the last drought. 

 If large quantities of water are 

 withdrawn during one of these 

 droughts, will the salt wedge move 

 far enough upstream to contaminate 

 the water at the intakes? Second, 

 the major wastewater treatment plant 

 for Washington is located about 10 

 miles downstream from the proposed 

 water supply intake. Will withdraw- 

 ing water reverse the flow of the 

 estuary sufficiently to cause the 

 wastewater plume to reach these 

 intakes? And third, will withdraw- 

 ing water during the droughts result 

 in sufficient change in the environ- 

 ment to threaten the integrity of the 

 ecosystem? 



In order to assist in answering 

 these questions, we are going to con- 

 duct a test on the Chesapeake Bay 

 Model. This test will be in 16 

 parts. In each part we will simulate 

 a constant flow into the estuary of 

 zero, 250, 500, or 900 mgd, combined 

 with a water supply withdrawal of 

 zero, 100, or 200 mgd. Under each 

 condition, the level of pollution 

 and the salt content of the water 

 will be determined. These data will 

 be input to the social, economic, and 



environmental analyses that are nec- 

 essary to determine the feasibility 

 of using the estuary as a supplemen- 

 tal water supply source for the 

 Washington Metropolitan Area. 



The water of the Potomac Estuary 

 is already rather polluted and it is 

 anticipated that advanced treatment 

 methods will be required to make it 

 potable. In order to develop these 

 methods, Congress has directed that 

 a pilot treatment plant be construct- 

 ed. We have already started work on 

 this plant and anticipate that it 

 will be completed next year. At that 

 time, a one-year research program 

 will be instituted. 



Last October, the State of 

 Maryland asked us to conduct for them 

 a short test on the Nanticoke River. 

 A large quantity of toxic materials 

 were stored at Sharptown, Maryland, 

 and the state was concerned that they 

 may somehow enter the waterway. 

 Through use of the model, we were 

 able to provide the state with the 

 data needed relative to the fate of 

 any toxic materials that may enter 

 the Nanticoke River. 



Another test which will be done 

 for the State of Maryland is related 

 to the dispersion of the thermal 

 plume from power plants. In this test 

 we will simulate the heated discharge 

 from an existing plant and a proposed 

 one. The thermal plume will be moni- 

 tored over a one-year period to 

 ascertain its rate and extent of dis- 

 persion. This test will also di- 

 rectly benefit the Corps of Engineers 

 as the State has already collected 

 some field data, and we can use these 

 data to verify that the model ac- 

 curately simulates dispersion. 



The High Freshwater Inflow Test 

 is one of our more important tests. 

 The objective of this test is to 



126 



