Grassy Lake Dam is a small dam operated by the U.S. Bureau of Reclamation in Teton County, Wyoming

Teton County, Wyoming

Teton County is a county located in the U.S. state of Wyoming. As of 2010, the population was 21,294. Its county seat is Jackson. Teton County contains the affluent Jackson Hole skiing area...

, immediately to the south of Yellowstone National Park

Yellowstone National Park

Yellowstone National Park, established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872, is a national park located primarily in the U.S. state of Wyoming, although it also extends into Montana and Idaho...

. The dam lies in a corridor of Bridger-Teton National Forest

Bridger-Teton National Forest

Bridger-Teton National Forest is located in western Wyoming, United States. The forest consists of , making it the second largest National Forest outside of Alaska. The forest stretches from Yellowstone National Park, along the eastern boundary of Grand Teton National Park and from there rides...

 that runs between Yellowstone and Grand Teton National Park

Grand Teton National Park

Grand Teton National Park is a United States National Park located in northwestern Wyoming, U.S. The Park consists of approximately and includes the major peaks of the long Teton Range as well as most of the northern sections of the valley known as Jackson Hole. Only south of Yellowstone...

s. The dam structure and outlets are within a few hundred feet of the south boundary of Yellowstone. The zoned earthfill dam was built between 1937 and 1939 as part of the Minidoka Project

Minidoka Project

The Minidoka Project is a series of public works by the U.S. Bureau of Reclamation to control the flow of the Snake River in Wyoming and Idaho, supplying irrigation water to farmlands in Idaho...

, which provides water to irrigate farmland in Idaho

Idaho

Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....

's Snake River Plain

Snake River Plain

The Snake River Plain is a geologic feature located primarily within the state of Idaho in the United States of America. It stretches about westward from northwest of the state of Wyoming to the Idaho-Oregon border. The plain is a wide flat bow-shaped depression, and covers about a quarter of Idaho...

.

The dam provides only water storage, impounding 15200 acre.ft. Given the small catchment area of Grassy Creek, inflow is augmented by a 0.7 miles (1.1 km) ditch that moves water from Cascade Creek into the reservoir.

Bechler Meadows dam proposals

The Grassy Lake Dam and the Island Park Reservoir in Idaho were the outcome of an ambitious plan to use the abundant waters of Yellowstone National Park for irrigation in Idaho, Montana and Wyoming. A variety of projects were proposed starting in 1919, the most advanced of which involved a proposed reservoir in the Bechler Meadows and Falls River regions of the southwest corner of the park, immediately to the north of the Grassy Lake site. In 1926 Idaho politicians led by Representative Addison T. Smith

Addison T. Smith

Addison Taylor Smith was a United States Representative from Idaho. Smith served as a Republican in the House from 1913 to 1933....

 proposed the withdrawal of the Bechler area from the park for construction of a reservoir to collect water for use in Idaho. The backlash from conservationists, who compared the proposed reservoir to the Hetch Hetchy Reservoir

Hetch Hetchy Reservoir

Hetch Hetchy Reservoir is a reservoir in Yosemite National Park, about northeast from the city of Merced, California. The reservoir has a capacity of and is formed by the concrete gravity O'Shaughnessy Dam in Hetch Hetchy Valley on the Tuolumne River...

 in Yosemite National Park

Yosemite National Park

Yosemite National Park is a United States National Park spanning eastern portions of Tuolumne, Mariposa and Madera counties in east central California, United States. The park covers an area of and reaches across the western slopes of the Sierra Nevada mountain chain...

, derailed the plan, along with disagreements between Wyoming, Montana and Idaho over water rights. The Grassy Lake and Island Park reservoirs

Island Park Dam

Island Park Dam is operated by the U.S. Bureau of Reclamation in Fremont County, Idaho. The dam lies in Targhee National Forest near Island Park...

were built outside the park as alternative storage sites.

External links

• Grassy Lake Dam at the Bureau of Reclamation