Reservoirs in Maryland

Reservoirs in Maryland
Name	Reservoirs in Maryland
Caption	Loch Raven Reservoir, Baltimore County
Location	Maryland, United States
Type	reservoir
Basin countries	United States
Inflow	Susquehanna River; Potomac River; Patuxent River; Patapsco River
Outflow	Chesapeake Bay tributaries
Created	19th–20th centuries

Contents

Reservoirs in Maryland Maryland contains a dense network of artificial lakes and impoundments that supply drinking water, flood control, hydroelectric power, and recreation across jurisdictions including Baltimore County, Montgomery County, Prince George's County, and Washington County. These impoundments interact with major waterways such as the Potomac River, Patuxent River, Patapsco River, and Susquehanna River, and are tied to institutions like the Baltimore City Department of Public Works, the U.S. Army Corps of Engineers, Montgomery County Department of Environmental Protection, and the Maryland Department of the Environment. Major reservoirs support municipalities including Baltimore, Annapolis, and Rockville, and influence ecosystems connected to the Chesapeake Bay and protected areas such as Patapsco Valley State Park and Gunpowder Falls State Park.

Overview

Maryland reservoirs range from municipal systems like Loch Raven Reservoir serving Baltimore City to federal impoundments such as Conowingo Dam on the Susquehanna River operated by Exelon Corporation and regulated under the Federal Energy Regulatory Commission. Many reservoirs originated with projects by the U.S. Bureau of Reclamation and state agencies to support urban growth in Baltimore County, Prince George's County, and Montgomery County. Watersheds feeding these reservoirs intersect with sites like Catoctin Mountain Park, Patuxent Research Refuge, and the Piedmont Plateau, and are monitored by networks such as the United States Geological Survey and the Maryland Department of Natural Resources.

Notable impoundments include Loch Raven Reservoir and Prettyboy Reservoir (Baltimore City water supply), Triadelphia Reservoir and Rocky Gorge Reservoir (Washington Suburban Sanitary Commission), Conowingo Dam (hydropower on the Susquehanna River), Deep Creek Lake (recreation and hydroelectric in Garrett County), and Liberty Reservoir (reservoir on the Patapsco River). Other significant structures are Brighton Dam, Little Seneca Lake (flood control and potable reserve near Gaithersburg), Jennings Randolph Lake (U.S. Army Corps project on the North Branch Potomac River), WSSC facilities, and municipal reservoirs supplying Annapolis and Frederick. Dams such as Conowingo Dam, Jennings Randolph Dam, Brighton Dam, Brighton Dam (Brighton, Maryland), and Pleasant Valley Reservoir are focal points for agencies including the National Park Service where projects abut parks such as Green Ridge State Forest and Cunningham Falls State Park.

Reservoir construction in Maryland accelerated with 19th-century urbanization of Baltimore and 20th-century electrification tied to companies like Exelon Corporation and utilities regulated by the Maryland Public Service Commission. Early projects referenced engineering practices from firms linked to the American Society of Civil Engineers and used design approaches shaped by flood events such as the Flood of 1936 and policy responses influenced by the National Flood Insurance Act of 1968. Federal involvement increased with the U.S. Army Corps of Engineers projects on the Potomac River and Conowingo Dam controversies involving U.S. Fish and Wildlife Service and the Chesapeake Bay Program. Reservoir siting considered colonial-era mills, transportation corridors like the Baltimore and Ohio Railroad, and landholdings associated with families documented in the Maryland Historical Trust.

Reservoir operations balance inflows from tributaries including the Gunpowder Falls, Prettyboy Creek, Rock Creek (Potomac River tributary), and Antietam Creek with withdrawals for municipalities such as Baltimore City and Silver Spring. Water quality and quantity are assessed via monitoring by the United States Geological Survey and managed under permits from the Maryland Department of the Environment and the Environmental Protection Agency. Interbasin transfers link systems across counties including Baltimore County, Howard County, and Montgomery County, while drought planning references frameworks from the Chesapeake Bay Program, Interstate Commission on the Potomac River Basin, and local utilities like the Washington Suburban Sanitary Commission (WSSC). Sediment transport from upstream agriculture and urban runoff involving stakeholders like the Maryland Farm Bureau and environmental NGOs such as the Chesapeake Bay Foundation affect reservoir storage and treatment requirements overseen by water treatment utilities including the Baltimore City Department of Public Works.

Reservoirs provide habitat for fishery resources including largemouth bass, striped bass, walleye, and migratory species that connect to the Chesapeake Bay estuarine system; their management involves agencies like the Maryland Department of Natural Resources and the U.S. Fish and Wildlife Service. Recreation at sites such as Deep Creek Lake, Loch Raven Reservoir, and Patuxent Reservoir supports boating, fishing, hiking, and birdwatching connected to organizations like the Audubon Society and state parks including Gunpowder Falls State Park. Issues such as invasive species (monitored by the Maryland Invasive Species Council), algal blooms studied by researchers at the University of Maryland, College Park, and riparian restoration projects funded by the National Fish and Wildlife Foundation shape ecological outcomes. Cultural resources near reservoirs are recorded by the Maryland Historical Trust and intersect with recreational planning by county parks departments in Baltimore County and Garrett County.

Management responsibilities are distributed among entities including the U.S. Army Corps of Engineers, Exelon Corporation, Washington Suburban Sanitary Commission, Baltimore City Department of Public Works, and the Maryland Department of the Environment. Regulatory frameworks draw on the Clean Water Act, permitting administered by the Environmental Protection Agency regional office, water allocation disputes mediated by the Interstate Commission on the Potomac River Basin, and licensing by the Federal Energy Regulatory Commission for hydroelectric projects like Conowingo Dam. Collaborative programs such as the Chesapeake Bay Program, watershed restoration initiatives with the Natural Resources Conservation Service, and academic partnerships with the University of Maryland Center for Environmental Science guide long-term planning, climate adaptation, and infrastructure investment coordinated with county governments including Montgomery County and Baltimore County.