Niobrara River Basin (Overview) HUC# 101500Basin Geography:
The Niobrara River flows east out of Wyoming and Niobrara County into Nebraska. The town of Lusk is centrally located in this small hydrologic unit. Rivers of the plains region of Wyoming, such as the Niobrara, exhibit different hydrology than other mountainous regions of the state. Streams are ephemeral or seasonal and not supplied by mountain runoff. Instead, spring snowmelt on the plains, summer thunderstorms and groundwater contribute to variable flows. Two seasonal flow peaks, in March and June, are characteristic.
High plains aquifers of the Ogallala Formation underlie the Niobrara River Basin in Wyoming. This factor sets this basin apart from other northeastern Wyoming basins. Niobrara basin aquifers produce good quality water for most purposes. However, aquifer levels are declining in the Ogallala region overall.
Relevant Compacts and Decrees:
The Upper Niobrara River Compact was signed by Nebraska and Wyoming in 1962. This agreement placed limitations on reservoir supply and direct flow water rights. Groundwater studies are stipulated if surface water supplies are impacted by groundwater development. Approximately 6700 acre-ft or two-thirds of the available streamflow is depleted by irrigation and evaporation before the Niobrara leaves Wyoming.
Wyoming Water Development Commission. 1990. Wyoming Water Atlas. University of Wyoming, Laramie. pp. 47.
US Geological Survey. 1985. National Water Summary-Wyoming: Surface Water Resources, Water Supply Paper 2300. pp. 494.
US Geological Survey. 1984. National Water Summary-Wyoming: Groundwater Resources, Water Supply Paper 2275. pp. 454.
Wyoming Water Development Commission & Wyoming State Engineer's Office. 1996. Wyoming Water Planning: A Report for Updating the Process. Cheyenne, WY. pp.16.