The Mount Morris Dam is a concrete gravity dry dam on the

Genesee River The Genesee River ( ) is a tributary of Lake Ontario flowing northward through the Twin Tiers of Pennsylvania and New York (state), New York in the United States. The river contains several waterfalls in New York at Letchworth State Park and Roch ...

. It is located at the northern end of

Letchworth State Park Letchworth State Park is a New York State Park located in Livingston and Wyoming Counties in western Upstate New York. The park is roughly long, following the course of the Genesee River as it flows north through a deep gorge and over several ...

, south of

Rochester, New York Rochester is a city in and the county seat, seat of government of Monroe County, New York, United States. It is the List of municipalities in New York, fourth-most populous city and 10th most-populated municipality in New York, with a populati ...

in the towns of

Leicester Leicester ( ) is a city status in the United Kingdom, city, Unitary authorities of England, unitary authority area, and the county town of Leicestershire in the East Midlands of England. It is the largest city in the East Midlands with a popula ...

and Mount Morris in

Livingston County, New York Livingston County is a county in the U.S. state of New York. As of the 2020 census, the population was 61,834. Its county seat is Geneseo. The county is named after Robert R. Livingston, who helped draft the Declaration of Independence a ...

. It is the largest dam of its type east of the

Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...

and its purpose is to mitigate downstream flooding between Mount Morris and

Lake Ontario Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north, west, and southwest by the Canadian province of Ontario, and on the south and east by the U.S. state of New York (state), New York. The Canada–United Sta ...

History

The Mt. Morris Dam was built between 1948 and 1952 by the Buffalo District office of the

U.S. Army Corps of Engineers The United States Army Corps of Engineers (USACE) is the military engineering branch of the United States Army. A direct reporting unit (DRU), it has three primary mission areas: Engineer Regiment, military construction, and civil wor ...

(USACE). The project was authorized by the

United States Congress The United States Congress is the legislature, legislative branch of the federal government of the United States. It is a Bicameralism, bicameral legislature, including a Lower house, lower body, the United States House of Representatives, ...

in the

Flood Control Act of 1944 The Pick-Sloan Flood Control Act of 1944 (P.L. 78–534), enacted in the 2nd session of the 78th Congress, is U.S. legislation that authorized the construction of numerous dams and modifications to previously existing dams, as well as levees ac ...

at a cost of $25 million. Prior to the construction of the dam, the Genesee River Valley and the city of Rochester had experienced periodic flooding. The flood of 1865, which developed flows exceeding per minute, resulted in massive destructions with flows equating to half the flows of

Niagara Falls Niagara Falls is a group of three waterfalls at the southern end of Niagara Gorge, spanning the Canada–United States border, border between the Provinces and territories of Canada, province of Ontario in Canada and the state of New York (s ...

. Severe floods occurred every seven years on average between 1865 and 1950. Prior projects in Rochester, including retaining walls and a deepening of the river, were insufficient to stop a major flood event. The USACE states that, in the years since the completion of the dam, an estimated $1 billion in flooding damages have been prevented. In June 1972,

Hurricane Agnes Hurricane Agnes was the List of costliest Atlantic hurricanes, costliest hurricane to hit the United States at the time, causing an estimated $2.1 billion in damage. The hurricane's death toll was 128. The effects of Agnes were widespread, ...

passed over the Genesee Valley, causing over 7 inches of rain to fall across the entire valley in a short period of time. The water inflow due to Hurricane Agnes exceeded the storage capacity of the reservoir and it was necessary to release water through the gates of the dam, causing minor downstream flooding. These releases were made to prevent overtopping of the spillway. Had the spillway overtopped, accumulated debris in the reservoir would have passed downstream, causing log jams and additional damage. Inflows of this magnitude are only expected to happen an average of every 300 years. An estimated $210 million in damages was prevented by the dam during the storm.

Commemorations

June 2002 commemorated the 50th anniversary of the completion of Mount Morris Dam. A celebration and dedication of the commemorative kiosk was held to honor and recognize the men and women employed by the U.S. Army Corps of Engineers, Buffalo District and Mount Morris Dam Builders, 1948–1952. The kiosk rests on a foundation of bricks, each of which is inscribed with the name and occupation of the builders.

Visiting Centers

The William B. Hoyt II Visitor Center at Mount Morris Dam, opened by the U.S. Army Corps of Engineers in 1999, was built to accommodate the thousands of people who visit the dam each year. This center features a large atrium, museum, theater and public restroom facilities.

Project facts

General
Distance from mouth of Genesee River: .
Drainage area above dam: .
Drainage area below dam: . Dam
Type: Concrete Gravity/Dry.
Total length: .
Top width: .
Maximum height above river bed: .
Top elevation: above sea level. Spillway
Total length: .
Crest elevation: . Reservoir
Length in River Miles: at Maximum flood control pool.
Water Surface Elevation: above sea level at Maximum flood control pool.
Storage Volume: at Maximum flood control pool. Outlet Works
Type: Rectangular conduits.
Location: Base of spillway.

References

External links