Arkansas River Basin Facts September 2000

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1ndangered Compact Facts Species Arkansas River Compact of 1948 The native greenback cutthroat trout The Compact apportions the - waters of dne Arkansas River between Colorado is the Colorado State Fish. It is (60 %) and Kansas (=10 %) based on the opinion of the U.S. Supreme Court in federally listed as threatened but has Colorado v Kansas, 320 LIS. 383 (1943). The Compact established the Ark-an- been reintroduced into many streams sas River Compact administration to prescribe procedures for Compact and lakes. The Arkansas darter is a administration, including three representatives froth Colorado (a water user federal candidate species for listing from above and below john Martin Reservoir and the Director of the under the Endangered Species Act Colorado eater Conservation Board), three Kansas representatives, and a and is listed as threatened by the federal representative. Colorado Division of Wildlife. Agriculture Agriculture, domestic and The 1980 Operating Principles provide for storage acrnunts in john Martin Unique Reservoir and the release of water from those accounts for Colorado and Charc-Lcteri sties Kansas water users. If the conservation pool in the reservoir is depleted, Colorado is required to administer water rights priorities in District 67 �. Erosion and channel instability in (downstream from John Martin). During such periods, Kansas is not lower reaches of Fountain Creek. entitled to water flowing into the reservoir, .'; An unusual groundwater mound exists at La Junta and is under Colorado and Kansas have litigated claims concerning Arkansas River water investigation, along with substan- since the early twentieth century. Supreme Court decrees establish principles of tial channel degradation. equitable apportionment of water between states. In 1995, Colorado was Development of water supplies found to have depleted stateline flows in violation of the Compact. "Ihe states will be limited and complex due to are now litigating the nature and extent of the injury to Kansas and the method the Compact allocation, interstate of repayment by Colorado before a Supreme Court appointed Special Master. litigation, and salinity concerns. In response to an order of the Special Nfaster, die Colorado State Engineer Litigation with Kansas over promulgated well administration rules to bring Colorado into compliance with compact issues. the Compact. I� ro L1 i'? Ciwate Upper Basin --Above _ Pueblo Reservoir Alluvium BedrockAquifer Aquifer Stream and glacial Dry Union Formation up Characteristics deposits -- silt to large to 500 ft thick. Fractured boulders granite -- Sawatch and basins within theArkan- Mosquito ranges; sas Basin include the carbonate rock -- Upper Black Squirrel and Leadville Primary Uses Domestic Yield Varies widely due to range of materials: up to 500 gpm at Salida to Buena Vista reach Water Quality Generally potable, a few local exceptions of natural and manmade contamination Source: Colorado Department of Natural Resources Domestic Varies widely: 10 to 200 gpm Lower Basin -- Below Pueblo Reservoir ShallowAiluvium Bedrock Aquifer Width varies from 1 to 10 Up to 1,000 ft thick. miles; 30 to 200 ft thick. Sandstone formation in Designated groundwater the Ogallala (Northern basins within theArkan- and Southern High Plains) sas Basin include the The southern part of the Upper Black Squirrel and Denver Basin bedrock Big Sandy. aquifers provides water to Douglas, El Paso and Elbert counties. Agriculture Agriculture, domestic and municipal _ 10 to 4,000 gpm, 50 to 500 gpm depending on location Generally potable, a few Degrades downstream Generally very good local exceptions of from good in the upper natural and manmade portion of the reach to contamination poor, only marginally useful for irrigation and stockwatering due to salinity