Lacreek National Wildlife Refuge
Mountain-Prairie Region

Moist-Soil Management

Lacreek Refuge has 13 water impoundments creating nearly 5,400 acres of shallow flooded marsh and open water habitat. Water can be added or removed from each impoundment via water control structures. Controlled water level manipulations are one of the most effective ways to manage wetlands for migratory birds. A perennial flow of water coming onto the refuge via Lake Creek, Cedar Creek, and Elm Creek coupled with the water control structures allow for moist-soil management opportunities. The term "moist-soil" refers to manipulating conditions within wetlands so that seeds from wetland plants (mostly annuals) can germinate, grow, and set seed. Typically at the refuge, the draw down stage will begin in late March and continue through early May. Draw downs during this time tend to maximize vegetation growth and seed production. In addition to the timing of the draw down, the rate of draw down plays an important role in determining which plants will grow. Generally speaking, all draw downs on the refuge are conducted at a gradual rate. Exposed mud flats created by slowly removing the water provides optimal feeding opportunities for migrating birds, especially shorebirds. As the growing season draws to a close, usually in early September, the moist soil units are shallowly flooded to provide feeding opportunities for migrating waterfowl. In addition, moist soil vegetation such as arrowhead produced during the summer months serves as important winter food resource for wintering trumpeter swans utilizing the refuge.

Drying out a wetland

Refuge staff intentionally dry some wetlands out through the summer to cause the break down of nutrients, stimulate germination and growth of desireable wetland plants, and kill carp.

Photo:USFWS, Tom Koerner

Annual Smartweed in seed

Many of the most desireable wetland plants, such as annual smartweed (Polygonum lapathafolium), are heavy seed or tuber producers and also support high numbers of aquatic insects.

Photo: USFWS, Tom Koerner

Waterfowl on Moist Soil

Wetlands that have been drawn down through the summer are shallowly flooded in the fall or the following spring. This provides critical food resources for migrating ducks, geese, and shorebirds as well as a natural winter food source for the many trumpeter swans, Canada geese, and mallards that remain with the open water provided by the springs.

Photo: USFWS, Tom Koerner

Last updated: November 2, 2012