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Stephen G. Custer

Publications and source records attributed to Stephen G. Custer.

2 recordsLinked to original sources

Hydrologic landscape units and adaptive management of intermountain wetlands

daptive management is often proposed to assist in the management of national wildlife refuges and allows the exploration of alternatives as well as the addition of ne w knowledge as it becomes available. The hydrological landscape unit can be a good foundation for such efforts. Red Rock Lakes National Wildlife Refuge (NWR) is in an intermountain basin dominated by vertical tectonics in the Northern Rocky Mountains. A geographic information system was used to define the boundaries for the hydrologic landscape units there. Units identified include alluvial fan, interfan, stream alluvi um and basin flat. Management alternatives can be informed by ex amination of processes that occu r on the units. For example, an ancient alluvial fan unit related to Red Rock Creek appear s to be isolated from stream flow today, with recharge dominated by precipitation and bedrock springs; while other alluvial fan units in the area have shallow ground water recharged from mountain streams and precipitation. The scale of hydrologic processes in interfan units differs from that in alluvial fan hydrologic landscape units. These differences are important when the refuge is evaluating habitat management activities. Hydrologic landscape units provide scientific unde rpinnings for the refuge’s comprehensive planning process. New geologic, hydrologic, and biologic knowledge can be integrated into the hydrologic landscape unit definition and improve adaptive management.

Montana↗

Saline-seep development in the Hailstone Basin, northern Stillwater County, Montana

As a result of an increase in saline seep occurrence in Montana, a study was begun in 1974 to determine the hydrogeology of saline seeps in the Hailstone basin. The aquifer is composed of colluvium of Holocene age. The impermeable Cretaceous Niobrara Formation underlies the saturated zone basinwide. The ground-water system is shallow, unconfined, and locally recharged. Ground-water levels and size of the saline seeps respond rapidly to precipitation in the basin. The appearance and growth of saline seeps are related to precipitation patterns; the agricultural practice of summer follow; topography; the presence of a shallow, unconfined, and locally recharged ground-water system; and a soluble salt source. Continuous cropping could reduce the amount of water percolating beneath local recharge areas, and thus minimize the water available for seep formation and growth. The lateral variation in chemical quality of water from wells suggests a shallow flow system. The field specific conductance of 29 ground-water samples collected in 1976 ranged from 2,160 to 14,000 micromhos per centimeter and averaged 6,660 micromhos per centimeter. Water from saline seeps in the study area contains principally sodium, magnesium, calcium, and sulfate. Nitrate is present in the ground water in concentrations of as much as 855 milligrams per liter. The high nitrate concentrations are interpreted to originate primarily from oxidation of organic material once native sod is broken by cultivation. (USGS).

Montana↗