Mortenson Lake National Wildlife Refuge


Wyoming toad, Mortenson Lake National Wildlife Refuge

Until recently, Mortenson Lake was the only known breeding place of the endangered Wyoming toad. Then the US Fish & Wildlife Service established a captive breeding population at Lake George (on nearby Hutton Lake National Wildlife Refuge) and the toads have a better chance of survival now.

Mortenson Lake NWR is composed of 1,776 acres and contains parts or all of four lakes. The property is southwest of the city of Laramie and the lakes are collectively known as "Laramie plains lakes." This is an alpine area covered with a mix of greasewood, grasslands and wetlands. The mean elevation of Mortenson Lake NWR is 7,256 feet.

The Wyoming toad used to be quite widespread across the environs of Albany County but habitat changes coupled with agricultural, grazing and pesticide pressures pushed the toad to the brink of extinction. The toad was first described as a separate species in 1946 but disaster set in so quickly that scientists thought the toad was extinct by 1980. Then, in 1987, a small population of them was found surviving at Mortenson Lake. The Nature Conservancy came up with funds and bought the land around the lake. After Congress did their thing, the US Fish & Wildlife Service was able to purchase the land from them and the refuge was officially established in 1993. Fish & Wildlife immediately went about capturing all the Wyoming toads they could find and began a captive breeding operation. Releases of individuals back into Mortenson Lake have been occurring since 1995 but the overall success of the program has yet to be seen. Because of the critical nature of the program, Mortenson Lake National Wildlife Refuge is closed to the public.

Mortenson Lake itself is managed solely to enhance the survivability of the Wyoming toad. The other lakes on the property are managed for waterfowl and other water birds. The uplands surrounding the lakes are managed to enhance the growth of native short grasses that support savannah sparrows, horned larks, western meadowlarks, Wyoming ground squirrels and pronghorn antelope. Cattle are allowed to graze on the property, too, because that grazing helps to keep open areas along the lakes' shorelines (the Wyoming toad has been shown to need that open area along the edge of the water).

Mortenson Lake National Wildlife Refuge is administered by Arapaho National Wildlife Refuge in Walden, Colorado.

Map of Mortenson Lake National Wildlife Refuge