The Blanca Wetlands Area of Critical Environmental Concern, or Blanca Wildlife Habitat Area, is an area of the San Luis Valley in Colorado, which serves as a refuge for birds, fish and other wildlife. The wetlands had been completely destroyed by pumping and diversion of water for irrigation. Starting in 1965 the Bureau of Land Management began to restore them, and they have become an increasingly important ecological habitat for shorebirds, water birds and other wildlife and native plants.. The region has a cool, dry climate, with about 107 frost-free days each year. Temperatures range from 30 °F to 85 °F (29 °C). Annual rainfall is about 7 inches (180 mm). The landscape is flat. Sand dunes carry sparse vegetation such as greasewood, rubber rabbit, salt grass, Sandhill muhly and sand drop seed. The areas of dunes are intermingled with depressions and basins of historical playas. As late as the 1800s the area was wet, and the bones of fish show that some of the water was at least 12 feet (3.7 m) deep. Loss of water and destruction of wetlands occurred in the twentieth century due to pumping and redirecting surface water for irrigation. By the mid-1900s the basins had completely dried up, and the area became known as "Dry Lakes".
In 1965 the San Luis Resource Area of the Bureau of Land Management began a project to restore some of the dry playas in the San Luis Valley to their former condition as wetlands. The Blanca Wildlife Habitat Area covers almost 10,000 acres (4,000 ha) south of San Luis Lakes and near to the Great Sand Dunes National Park and Preserve. In contains about two hundred shallow basins floored by layers of sand and clay, holding wet meadows, salt flats, marshes and fresh water ponds. As of 1989 the Habitat Area contained 1,400 acres (570 ha) of pond and wetlands, with another 475 acres (192 ha) of historical wetlands to be developed. Wetland vegetation in the playas includes soft stem bulrush, cattail, alkaline bulrush, spike rush, sago pondweed, longleaf pondweed and watermilfoil. About 1,200 acres (490 ha) are watered each year, while other parts are deliberately allowed to dry up.
Wildlife: The wetlands is one of the most important areas for birds in Colorado since it provides habitat for migrating water birds or shorebirds. It hosts thirteen threatened, endangered and sensitive species. The bald eagle and the peregrine falcon use the wetlands. The snowy plover and the white-faced ibis have been documented as nesting. Other Species of Management Priority that have been documented are American bittern, avocet, common yellowthroat, eared grebe, Forster''s tern, greater Sandhill crane, hen harrier, Savannah sparrow, snowy egret, sora rail, western grebe and yellow-headed blackbird. Shorebirds such as gulls, sandpipers and pelicans are at home in the salty environment, as well as 158 other species. There is a breeding population of snowy plover. The wetlands is a duck breeding concentration area, with mallards by far the most common, but good numbers of pintail and green-winged teal also visiting.
The wetlands could become critical for conserving amphibians in the valley. There is a healthy population of Great Plains toads. Other documented amphibians include the plains spadefoot toad, western chorus frog, leopard frog and tiger salamander. There are several species of bat in the wetlands. The least chipmunk is common in the greasewood parks that adjoin the wetlands and the Ord''s kangaroo rat lives in the sand dunes. Muskrats and coyotes are present, and mule deer and elk are often seen in the wetland area.