Grassy Lake Dam facts for kids
Quick facts for kids Grassy Lake Dam |
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 Location of Grassy Lake Dam in Wyoming
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| Location | Teton County, Wyoming, near Yellowstone National Park |
| Coordinates | 44°07′51.52″N 110°49′07.77″W / 44.1309778°N 110.8188250°W |
| Construction began | 1937 |
| Opening date | 1939 |
| Operator(s) | U.S. Bureau of Reclamation |
| Dam and spillways | |
| Type of dam | Zoned earthfill dam |
| Impounds | Grassy Creek |
| Height | 118 ft (36 m) |
| Length | 1,170 ft (360 m) |
| Spillway capacity | Ungated bathtub |
| Reservoir | |
| Creates | Grassy Creek Reservoir |
| Total capacity | 15,200 acre-feet (0.0187 km3) |
| Catchment area | 3.65 sq mi (9.5 km2) |
The Grassy Lake Dam is a small dam in Wyoming. It is operated by the U.S. Bureau of Reclamation. You can find it in Teton County, Wyoming, just south of Yellowstone National Park.
The dam is located in a special area. This area is part of the Bridger-Teton National Forest. It runs between Yellowstone and Grand Teton National Parks. The dam itself is very close to Yellowstone's southern border.
Workers built the Grassy Lake Dam between 1937 and 1939. It is an earthfill dam, which means it's made mostly of earth and rock. The dam is part of a bigger plan called the Minidoka Project. This project helps bring water to farms in Idaho's Snake River Plain.
The dam's main job is to store water. It can hold about 15,200 acre-feet (0.0187 km3) of water. Since Grassy Creek is a small stream, more water is added. A ditch about 0.7-mile (1.1 km) long brings water from Cascade Creek into the reservoir. This helps make sure there's enough water for the farms.
Contents
Why Grassy Lake Dam Was Built
Early Ideas for Water Storage
Before Grassy Lake Dam, there were big plans to use water from Yellowstone National Park. This water was needed to help farms in Idaho, Montana, and Wyoming. Many ideas for dams and reservoirs were suggested starting in 1919.
Protecting Yellowstone National Park
One major idea was to build a reservoir in the Bechler Meadows area. This area is in the southwest part of Yellowstone Park. It is just north of where Grassy Lake Dam is now. In 1926, politicians from Idaho wanted to remove this area from the park. They wanted to build a reservoir there to collect water for Idaho farms.
The Fight for Conservation
This idea caused a lot of disagreement. People who wanted to protect nature, called conservationists, were very upset. They compared this plan to the Hetch Hetchy Reservoir in Yosemite National Park. That reservoir was built inside a national park, which many people thought was a mistake.
There were also arguments between Wyoming, Montana, and Idaho. They disagreed about who had the right to use the water. Because of these disagreements and the strong protests from conservationists, the plan to build a dam inside Yellowstone Park was stopped.
Finding Other Solutions
Instead of building inside the park, new places were found outside. The Grassy Lake Dam and the Island Park Reservoir were built in these new locations. This way, the farms still got the water they needed, and Yellowstone National Park was protected.
