Closed Basin Project
Coordinates: 37°32′58″N 105°40′26″W / 37.549486°N 105.673844°W
The Closed Basin Project is a groundwater extraction project in the San Luis Valley in Colorado, United States, operated by the United States Bureau of Reclamation.
A closed basin is a hydrologic basin that has no outlet for the water. Precipitation can only leave through evaporation or seepage. The closed basin of the San Luis Valley covers 2,940 square miles (7,600 km2) between the San Luis Hills in the south, the San Juan Mountains to the west, Poncha Pass to the north and the Sangre de Cristo Mountains to the east. The basin is separated by a hydraulic divide at the southern end from the Rio Grande watershed. It contains the towns of Center, Hooper, Moffat, Mosca and Saguache and the Great Sand Dunes National Park and Preserve.
Streams that flow into the basin include irrigation diversions from the Rio Grande, the Carnero, La Garita, and Saguache creeks from the west, San Luis Creek from the north, and the North Crestone and Sand creeks from the east. The water spreads over the floor of the valley and either sinks into the underground aquifer or evaporates. The lowest part of the basin extends from the San Luis lakes north to the Blanca Wildlife Habitat Area. In this area the water table is very close to the surface. Water can evaporate directly from the soil or be taken up by plants such as salt grass, rabbit brush and greasewood, which release the water through evapotranspiration.
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