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Reservoir Watershed Management Program

A voluntary interagency partnership to protect the major reservoirs in Metropolitan Baltimore

One of the region’s most valuable natural assets  is our reservoir system

The Loch Raven, Prettyboy and Liberty Reservoirs together provide high-quality water for approximately 1.8 million people in Baltimore City and the five surrounding counties. In addition, more than half the homes and several communities in the 467-square-mile reservoir watershed area depend on wells that draw from the watersheds’ groundwater.

The majority of the reservoir watershed area (290 square miles) is in Baltimore County.  Another 165 square miles are in Carroll County. Very small portions are in Harford County and southern Pennsylvania.  Only six percent of the watershed is owned by Baltimore City, which owns the three reservoirs and operates the central regional water system.

Reservoir Watersheds

In addition to being the principal water supply source for the region, the reservoirs and their tributary streams offer extensive recreational opportunities and provide extensive and diverse habitats for fish and other wildlife.  The reservoirs and their tributaries are aesthetic and recreational treasures.


Pollution problems in the reservoir watersheds became very apparent during the 1970s and early '80s when algal blooms caused treatment problems and taste and odor issues for drinking-water customers.  In the early 1970s, all three reservoirs were found to be in various states of eutrophication caused by too much phosphorus. Coordinated action had to be taken to correct the problems and to establish a basis for continual improvement in water quality in the reservoirs.

Reservoir Watershed Management Agreement

The above concerns led to an early Reservoir Agreement in 1979, which was significantly trengthened in 1984. This has been replaced by an expanded Reservoir Agreement signed in 2005. Signatories include Baltimore and Carroll Counties, Baltimore City, Baltimore County Soil Conservation District, Carroll Soil Conservation District, the Maryland Departments of Agriculture and the Environment, and the Baltimore Metropolitan Council. Other governments which participate include Anne Arundel, Harford and Howard Counties, all of them major users of reservoir water.


The 2005 Agreement has the fundamental goal of ensuring that the three reservoirs and their respective watersheds will continue to serve as sources of high-quality raw water for the Baltimore metropolitan water-supply system. Other goals address future loadings to the reservoirs of phosphorus, sediment, bacteria, sodium and chlorides; reducing the risk of contamination by hazardous materials; and promoting beneficial patterns of land use in the three watersheds. (See the actual agreement for more details.)

Roles and Responsibilities

Local elected executives and state agency heads approved the 2005 Agreement (pdf: 100 KB) and the 2005 Action Strategy (pdf: 56 KB). The Reservoir Watershed Protection Committee provides program oversight and guidance. The Reservoir Technical Group, composed of water quality staff from the signatory and participating organizations, meets bi-monthly to address emerging issues, to coordinate program work efforts, to review technical work, and to prepare reports called for in the Action Strategy.

In most cases, specific action items are implemented by the state and local agencies, working through their regulatory programs, planning and zoning programs, development ordinances, public works services, and other programs, such as farm conservation planning and nutrient management, which provide direct assistance to landowners.

Action Strategy

The Action Strategy is a set of implementation actions (policies, studies, and new efforts) by the participating organizations that support the goals. Included are policies or actions in the following areas: water quality monitoring and analysis; point source management (i.e. wastewater and industrial discharges); nonpoint source management (i.e., agricultural practices; stormwater and sewerage systems; septic systems); planning, zoning & development; resource protection and restoration; management of city-owned watersheds; toxics, spills, pathogens, and disinfectant by-products; reservoir watershed program coordination; and public awareness. A progress report on the implementation of the Action Strategy commitments since 2005 was released by the program in October 2009.

Public Awareness

The Reservoir Watershed Management Program promotes public awareness through collaboration with local stakeholder groups and by giving talks, presenting workshops, and preparing information and exhibits. Program meetings are open to the public. Watershed residents and groups receive e-mailed notification of upcoming meetings. From time to time, the Program releases technical and progress reports to the public. 

The 2004 Technical Report: Water Quality Assessment, Targeted Studies and Ongoing Water Quality Issues in the Baltimore Metropoliotan Water Supply Reservoirs and Their Watersheds is available online.

For more information:
Jim Slater, This email address is being protected from spambots. You need JavaScript enabled to view it.

Last Updated on Tuesday, 25 July 2017 18:24