Upper Arkansas River Subbasin

The Upper Arkansas River subbasin is made up of the Arkansas River and three distinct aquifer systems including the Arkansas alluvial aquifer, the Ogallala-High Plains aquifer and the Dakota aquifer. The Arkansas River originates in Colorado and transverses through Hamilton, Kearny, Finney, Gray and Ford Counties in Kansas as it flows eastward. An appreciable quantity of Upper Arkansas River surface water originates from calls for water out of John Martin Reservoir, irrigation canal return flows in eastern Colorado and alluvial bank discharge after high flow events in the system. The Arkansas River recharges the shallow alluvial aquifer and provides irrigation water to a network of ditches and Lake McKinney, a temporary holding basin for irrigation.

Upper Arkansas Subbasin

The Upper Arkansas subbasin consists of 2,528,124 acres, and contains all or parts of 11 counties. The climate is semiarid with precipitation ranging from 15.8 inches at Syracuse to 21.5 inches at Dodge City. The subbasin lies in the High Plains physiographic region and the dominant economies are agriculture, and oil and natrual gas production. Most irrigation in the subbasin obtains groundwater from the Ogallala-High Plains aquifer, but an extensive network of ditches diverts surface water from the Arkansas River from the Colorado line east to Garden City. The Upper Arkansas working group, consisting primarily of ditch service operators, submitted Recommendations for the Upper Arkansas River Subbasin in 2002 to the chief engineer that address water resource issues in the subbasin.

The water used by the Associated Ditches of Kansas is governed by a compact between Colorado and Kansas, and an Intensive Groundwater Use Control Area is in place along the entire alluvial corridor, as shown on the map above. Most of the Upper Arkansas subbasin falls under the local jurisdiction of the Southwest Kansas Groundwater Management District No. 3, while a small portion is within the Western Kansas Groundwater Management District No. 1.

Colorado-Kansas Interstate Compact

Water flowing in the Arkansas River into Kansas from Colorado is governed by the Colorado-Kansas Interstate Compact. In 1985, Kansas filed a complaint in the United States Supreme Court arguing that post-compact wells in Colorado had materially depleted the waters of the Arkansas River in violation of the compact. In 1994, the compact Special Master asked the United States Supreme Court to determine that Colorado had violated the compact by allowing post-compact well pumping along the Arkansas River and, on May 15, 1995, the Supreme Court agreed. From 1995 to present, the damages and remedies phase of trial have been under way. On April 29, 2005, Colorado paid Kansas more than $34 million in damages for compact violations that occurred between 1950 and 1999. Colorado paid an additional $1 million on June 29, 2006. This money has been deposited into three funds created by Kansas statute that specify how and where the money will be spent. Currently, Kansas and Colorado are waiting for the Special Master's fifth and final report, which will include the final decree.

Issues:

  • Groundwater depletion related to diversion for irrigation agriculture
  • Evapotranspitation by phreatophytes
  • Saltwater intrusion into the groundwater from the Arkansas River
  • Channel impairment by reduction in peak flows, changes in flood plain vegetation, and encroachment onto the channel and floodway by land use changes

Goals:

  • Extend and conserve the life of the associated aquifers
  • Reduce the infestation of phreatophytes
  • Reduce the average concentration of total dissolved salts in the Arkansas River entering Kansas, which will in turn lessen the risk of salt entering groundwater
  • Manage the water flow of the Arkansas River for long-term sustainability, and improve channel and floodway conditions

Current Activities:

  • Promote water rights purchases for stream-aquifer recovery
  • Adoption of a ten-year tamarisk control plan
  • Target water use reduction where water quality benefits will occur
  • Look at potential stretches of the Arkansas River channel to improve to lessen flooding and phreatophyte consumption

Groundwater Flow Model:

  • The Kansas Geological Survey is in the beginning stages of contructing the steady state model, with pre-development calibration, and then will move onto the transient model for Southwest Kansas Groundwater Management District No. 3. The focus of the Southwest Kansas Groundwater Management District No. 3 model is to learn more about aquifer storage and change through time within the Upper Arkansas subbasin. The projected completion date for the model is in 2010