The Sixes Bridge Impoundment and Saving the Monocacy River (part 1)

Lacking local historical awareness, we may sometimes think in Frederick County that those folks who’ve lived here fewer years and who present an environmentalist viewpoint are outsiders, but in truth, when you know the history of water quality and water sourcing issues here, you see that the environmental movements grew right out of farmers and property rights advocates. The fight to stop the Army Corps of Engineers from building the Sixes Bridge Dam here as proposed in 1963 proves the point.

Proposed Sixes Bridge Impoundment on the Monocacy River (click on the image to open a larger version)

Proposed Sixes Bridge Impoundment on the Monocacy River (click on the image to open a larger version)

Historical attention to water quality issues originated from health impacts on humans. By the 1890’s epidemics of cholera and typhoid led public health officials to begin bacteriological testing. Legal issues with controlling pollution soon became interstate issues because farms in one state were being impacted by pollution from neighboring states.

Filtration and chlorination of drinking water for urban areas ensued. Long before larger public awareness resulted in Chesapeake Bay regulations and concerns, the property rights movement fought to protect landowners whom pollutions effects. Early movements by groups like the Izaak Walton League in the 1920’s for water quality led to initial conservation efforts.

Studies and reports continued to demonstrate issues with national waters until Congress began to notice and react. Water supply meant that upstream pollution, at first sewage, must be mitigated.

The Flood Control Act of 1936 resulted in the Army Corps of Engineers moving from navigational improvements to large-scale dam and river basin planning.

By 1940 Federal water quality regulations were adopted nationally, and in our region the Interstate Commission for the Potomac River Basin (ICPRB) was formed to help the Potomac basin states and the federal government to enhance, protect, and conserve the water and associated land resources of the Potomac River basin through regional and interstate cooperation.

In 1946 the Washington Aqueduct and District of Columbia jointly published a four stage future water supply plan. Stages I and II increased water filtration and distribution improvements, Stage III a new intake at Little Falls, and Stage IV filters to increase existing capacity and other distribution improvements. It was already known that Potomac low flow was 502 Mgd and that droughts would cause water restrictions. “Thus it is evident that storage facilities on the Potomac River are needed now.” reported the study. Civil defense of integrated supply was also noted as a benefit.

The same year the Army Corps produced a survey study recommending a series of Potomac dams to aid flood control, water supply, highways, navigation and recreation, and water power. The dam plans and a highway proposed along the C&O canal led to development of the national park. The Corps list included over 100 potential dam sites.

A Riverbend Dam of 235 feet height at Seneca would supply needs until 2025, and a couple lesser dams would cover until 2080. The Riverbend Dam would’ve backed water up the Monocacy River to Walkersville. The second scenario was a lower Riverbend and smaller reservoirs at eight locations including the Monocacy. A third plan omitted Riverbend for more medium reservoirs.

There are at least two broad patterns in the story of the proposal for the Sixes Bridge Dam in Frederick County, Md. First, once government starts an idea, it barely changes and all officials are on board spouting the exact same party line, correct or not. Two, only after citizens fight and question a long time does the process begin to shift and actually work and make better sense.

Thankfully, while it often seems frustrating to citizens and paints government action and officials with public cynicism, our form of government allows grassroots determination and change to play its role and work out a compromise. It is up to responsible citizens to do their part to insure good governmental actions.


Opponents gained arguments from the 1946 studies, loss of farmland, and a loss of tax base, mud flats, loss of trails and recreation, and diminished fish species.

The studies that predicted the Potomac watershed would run out of drinking water and require augmentation began in the 1950’s. The planning and allocating large resources for a goal of protecting the public sometimes ran to extreme lengths, children were being taught to duck and cover under school desks, and families were constructing backyard concrete bunkers for civil defense. Much like today, science was not being implemented well in policy.

It is interesting to note that the Army Corps was opposed to Loudoun County’s proposal in 1956 to allow Potomac Electric Power’s generation plant on the Potomac there because they were already planning the Riverbend Dam, as well as several others on the main stem.

Consideration of the establishment of the Chesapeake & Ohio Canal National Park provided another context of the dam wars as its legislation set preservation of the Canal property against all encroachments—including water impoundment projects along the main stem of the Potomac River—as an integral part of the proposal to give the area National Historical Park status.

A minor drought in 1955 caused Congress to direct the Army Corps of Engineers to prepare a long range water supply plan.

In 1958, the Department of Health and Human Services, Public Health Service issued the Report of the Potomac River Basin Study in cooperation with the states of Maryland, Virginia, West Virginia, and Pennsylvania. It analyzed water sources and uses and populations served. It was the background to estimate needs and project future needs.

The study recommended several actions. Tributary surveys and evaluation of reservoir sites. A water quality survey was to be conducted. A sub context for managing water supply was that it had to be sufficient to allow wastewater contributions to waterways without excessive pollution effects. Between 1932 and 1956, the District of Columbia had doubled its raw sewage disposal direct to the Potomac River. The very same problem that caused their water concerns beginning in 1898.

In 1963 the US Army Engineer District, Baltimore Region, issued its response report on future water supply for the Potomac watershed. It said the Corps was considering twenty-three potential reservoirs with multiple purposes, to meet water flow requirements and provide supply and protect water quality. It also proposed over 400 minor ponds.

Site number eleven was the Monocacy River above Frederick, Maryland. The dam on the Monocacy River would be near Sixes Bridge Road where natural topography suggested that the damming of a large reservoir was an easily obtainable project that could supply Frederick, Gettysburg and Washington, DC. The dam would be 2240 feet long and 73 feet high. It would create a 3500 acre lake.

The Corps presented five alternative development plan scenarios.

The Army Corps began promoting the reservoir plans and lining up support for funding. The initial construction estimates began to narrow down, first to seven dams, then to the so-called “six pack.” Eventually this further boiled down to two projects, the Monocacy and Verona Va. projects.

Local officials and at first Federal officials supported the project, but local citizens activated against the project plan. For a decade the newspaper accounts argued for and against the project.


In 1966 the Potomac drought reached below the low water flow mark of 500 Mgd to 388 Mgd at Little Falls. The Washington Suburban Sanitary Commission’s drinking water intake went dry.

In 1969 Maryland set up the Maryland Potomac Water Authority agreeing to purchase new reservoir capacity at Bloomington, which became Jennings Randolph Reservoir.

Interconnectedness of water supplies on a large watershed basis was beginning to be understood, but the response to planning water sourcing was based on overkill and inaccuracy. It is generally understood that many Army Corps of Engineers projects of the time, while well purposed and successful in some ways, say flood control, were actually environmentally harmful in the long run.

In September 1969, Democratic Senator Joseph Tydings said, “Unless the Sixes Bridge project is started now, 1985 water demands will exceed the Potomac’s flow.” He also said the project should be separated from five others, which were bogged down in controversy.

Republican Senator Charles Matthias said the project was vital to the health, safety and economic growth of Frederick County.

As described above, in 1963, the Army Corps of Engineers proposed to dam the Monocacy River, and create a huge lake from Sixes Bridge up to Marsh Creek (in Pennsylvania), nearly taking in Emmitsburg. Local farmers and landowners fought it for nearly fifteen years, and won!

Come hear Jack Lynch share the story , this Wednesday, January 6th, at 7:00pm, at the Monocacy Scenic River Board meeting at Winchester Hall. Members of the public are welcome.

The River Board was established to protect the Monocacy, in large part due to this dam proposal, and a citizen led “Save the Monocacy” campaign.

EDITED on January 8th to note the link to Part II of this story: