Solomon River Basin
The Solomon River Basin drains approximately 6,840 square miles of land in northwest and north central Kansas. It is located within Sherman, Thomas, Decatur, Sheridan, Norton, Graham, Phillips, Rooks, Smith, Osborne, Jewell, Mitchell, Lincoln, Cloud, Ottawa, Dickinson and Saline counties. The western part of the Solomon basin falls under the jurisdiction of the Northwest Kansas Groundwater Management District #4.
It is characterized by two distict regions of the Great Plains: the High Plains and the Smoky Hills. The High Plains region extends from the western stateline eastward into Graham County. The topography is characterized by flat to gently rolling hills with narrow, shallow valleys of low relief. Sand, gravel and porous rock cover most of the region.
The Smoky Hills Physiographic Region covers most of Rooks County and extends as far east as Clay County. The Smoky Hills are composed of Cretaceous age rocks that form three distinct hill ranges. The western range of hills is characterized by steep chalk bluffs that can be found in areas south of the Solomon River and along the Smoky Hill River. The middle range of hills is capped by the Greenhorn Limestone. This area is known as "post rock country" because quarried limestone was used as fence posts by farmers. The easternmost range of hills is capped by the Dakota Sandstone. The eastern boundary of the Smoky Hills is in Clay County where the Flint Hills Physiographic region begins.
The elevation varies from approximately 3,300 ft. in the western part of the basin to 1,150 ft. in the eastern part near the town of Solomon. The average gradient for the North Fork and South Fork regions is approximately 14-15 ft/mile. The average gradient for the main stem is 5 ft/mile.
Three aquifer systems lie within the Solomon River Basin including alluvial, Ogallala and Dakota. The alluvium can be found in the channels and flood plains of all the major streams. The thickness of the deposits vary from approximately 10 to 60 feet. The Ogallala component of the High Plains is the main aquifer in the western part of the basin. It varies in saturated thickness from less than 50 feet to greater than 200 feet. The Dakota formation exists under both confined and unconfined conditions in the basin. The Dakota is confined by the Graneros Shale in the western Solomon basin. The Dakota is unconfined as it outcrops in the eastern part of the basin in Mitchell, Lincoln, Ottawa and Cloud counties. The water quality is generally poor in the eastern part.
The Solomon River Basin has three federally operated reservoirs with associated irrigation districts. The reservoirs were constructed by the US Bureau of Reclamation to provide flood control and irrigation storage for the area. Kirwin Reservoir was completed in 1955, followed by Webster Reservoir in 1956 and finally Glen Elder Reservoir (Waconda) was completed in 1969. The Kansas Department of Wildlife and Parks manages Webster and Glen Elder state parks and the US Fish and Wildlife Service operates and manages the Kirwin Wildlife Refuge. Approximately 25,394 acres are located within the three irrigation districts of the basin.
Issues:
- Groundwater depletion due to pumping in the Ogallala-High Plains and alluvial aquifers
- Depleted streamflow and inflows into reservoirs
Goals:
- Manage the alluvial aquifer system and surface water in the Solomon Basin for long-term sustainability.
- Extend and conserve the life of the Ogallala-High Plains Aquifer.
Current Activities:
- Develop management scenarios in the Northwest Kansas Model Area.
- In coordination with Solomon Working Group, SWRMP is running management scenarios for the Upper North and South Forks Model.
- Monitoring streamflow and groundwater throughout the basin.
Groundwater Flow Model:
- The Republican River Compact Model (RRCA) was refined by S.S. Papadopulos and Associates (SSPA) for use in Northwest Kansas. The model is an extension of the Republican River Compact Model used by Colorado, Nebraska and Kansas. Participants involved in this Northwest Kansas modeling effort were USBR, KWO, KDA-DWR and GMD 4. This model focused on Ogallala-High Plains Aquifer in GMD 4. GMD 4 is in the process of developing management options and implementing them.
- The Upper North Fork and Upper South Fork models were also developed by SSPA as an extension onto the Northwest Kansas Model. These models had the same participants as the Northwest Kansas Model. The Solomon Working Group discussed and submitted management scenarios to be run by SSPA.