Potomac River basin reservoir projects
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The Potomac River basin reservoir projects were U.S. Army Corps of Engineers programs that sought to regulate the flow of the Potomac River to control flooding, to assure a reliable water supply for Washington, D.C., and to provide recreational opportunities. Beginning in 1921 the Corps studied a variety of proposals for an ambitious program of dam construction on the Potomac and its tributaries, which proposed as many as sixteen major dam and reservoir projects. The most ambitious proposals would have created a nearly continuous chain of reservoirs from tidewater to Cumberland, Maryland. The 1938 program was focused on flood control, on the heels of a major flood in 1936. The reformulated 1963 program focused on water supply and quality, mitigating upstream pollution from sewage and coal mine waste.
While several projects came to fruition in one form or another, most were never pursued or were abandoned after significant public opposition. Savage River was the only project from the 1938 program to be built. The largest project to be proposed was Seneca Dam on the Potomac just above Washington, D.C.. The Seneca project was abandoned in 1969 after the creation of Chesapeake and Ohio Canal National Historical Park, which preserved much of the area Seneca Dam would have flooded. The Verona and Sixes Bridge projects survived into the 1970s. Only the Bloomington project was built approximately as originally proposed, creating Jennings Randolph Reservoir.
In 1968 the landmark study The Nation's River was published by the Department of the Interior, examining strategies for the appropriate use and clean-up of the Potomac. It disputed the strategy of dilution and noted that flood control projects could not be economically justified on their own. The report documented absent or inadequate wastewater treatment, discharge from combined sanitary and stormwater sewers, and agricultural runoff.[1] This document became the basis for Potomac study, development and management.[2] The widespread implementation of pollution controls as a result of the Clean Water Act reduced upstream pollution. Water conservation measures meant that water use did not follow the trend expected by the Corps of Engineers, and reservoirs were not required to meet demand.
The river's potential for transportation and hydropower was explored from the beginning of the United States, with George Washington's Potomac Company one of the first consortia to try to exploit the Potomac's route through the Blue Ridge and Allegheny Mountains. The failure of the Potomac Company led to the formation of the Chesapeake and Ohio Canal in 1825 to use the river's route to build a still-water canal to Cumberland. Starting in 1799 the Potomac and Shenandoah rivers were used to power the federal arsenal at Harpers Ferry. A variety of industries grew up in the area, powered by river waters.
The earliest proposals for exploitation of hydropower on the Potomac were made in the 1880s. By the 1920s the U.S. Army Corps of Engineers reviewed the possibilities for hydroelectric power at Great Falls.[3] Power generation capacity was planned at 105 MW[4] and total cost was projected at $18,616,000 in 1921.[5]
1938 Corps of Engineers program
As a result of the catastrophic flood of 1936, Congress mandated a study by the Corps of Engineers on flood control on the Potomac. The Corps report published in 1938 proposed a series of dams on the main stem of the Potomac and on several tributaries. The reservoirs were to start at tidewater at Chain Bridge.
Proposed dams on the Potomac included (unbuilt projects in italics):
- Chain Bridge: planned dam to impound the river beginning at tidewater, backing up to Bear Island. Built on a reduced scale in 1959 as Little Falls Dam, about 3 miles (4.8 km) above tidewater. The built version is 14 feet (4.3 m) high and functions as a weir to impound water at the Washington Aqueduct intake.[6][7]
- Bear Island: proposed to create a reservoir extending from the top of the Chain Bridge pool at Bear Island to the base of Great Falls, never built
- Riverbend: proposed at the sharp bend of the Potomac immediately above Great Falls. The 119-foot (36 m) dam would have created a reservoir extending nearly to Harpers Ferry. Superseded by the Seneca Dam proposal farther upriver, also never built.
- Harpers Ferry: Proposed in the vicinity of Sandy Hook and Weverton, the reservoir would have flooded the lower part of Harpers Ferry with a pool extending past Shepherdstown. It was never built.
- Rocky Marsh: Proposed for a site near Scrabble, never built. The site would have been near the Chesapeake and Ohio Canal's Dam No. 4., which survives.
- Pinesburg Proposed for a site near Pinesburg, never built. The site would have been near the historical and present-day Dam No. 5.
- Orleans: Proposed for a site near Little Orleans, never built.[8]
The Shenandoah would have been dammed at two places:
- Millville: The existing small power generation dam at Millville would have been replaced with a much larger structure with a pool extending to Front Royal. Never built. The original 2.84 MW generating station continues to operate.
- Brocks Gap: Like the Riverbend/Seneca Dam project, the Brocks Gap project survived into the 1960s, when it was defeated by local opposition.[8]
Other reservoirs would have included:
- Edes Fort on the Cacapon River. Never built.
- Springfield on the South Branch of the Potomac. Never built.
- Royal Glen on the South Branch, proposed again in 1963. Never built.
- Patterson Creek Never built.
- Keyser on the North Branch of the Potomac. Never built.
With the intervention of World War II none of these projects were pursued, but they were revived in 1945 as a basis for further study.[8]
- Savage River was the only project of the 1938 program to be built as envisioned. The 184-foot (56 m) rockfill dam was completed in 1952.
