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Groundwater Sources and Supply (Figure WS-01)

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Groundwater Sources and Supply (Figure WS-01) Water Supply Hydrologic models have been developed for many areas to further understand groundwater availability and use Groundwater Sources and Supply (Figure WS-01). Models help define the total water budget of a region and predict the response of the water system to Kansas regulations broadly define groundwater as “water changing conditions, such as droughts or floods, increased located under the surface of the land that is or can be the withdrawals or conservation measures. source of supply for wells, springs, or seeps, or that is held in aquifers or the soil profile” (K.A.R. 28-16-28b(dd)). In addition to the areas shown in Figure WS-01, a comput- Groundwater in Kansas occurs in all of these features and er model is under development for the Western Kansas is present across the state in various quantities, qualities Groundwater Management District No. 1 (GMD) region and depths. Progressing west to east across the state, deep which includes portions of Greeley, Wichita, Scott, Wal- saturated aquifers change to shallower alluvial aquifers in lace and Lane counties. The Ogallala portion of the High most areas. Plains aquifer is the primary source of water in this region. In western and south central Kansas, groundwater has histori- cally been the most reliable source of large volumes of water for municipal, industrial and irri- gation use. Quantities of availa- ble groundwater are declining in many areas, often due to overde- velopment. The Ogallala portion of the High Plains aquifer re- charges at about one-half inch per year. Current irrigation prac- tices pump water from the aqui- fer at a rate of two to four feet per year, and more. In western Kansas, naturally lim- ited surface water supplies, char- acteristic of a semi-arid climate, has been exacerbated by the de- cline of groundwater levels that historically provided baseflow to Figure WS-01. Locations of Hydrologic Models streams. In the past 50 years, many streams have gradually changed to intermittent or Aquifers in Kansas even ephemeral streams as the effects of lowering of the water table have manifested. Alluvial Aquifers Scientists in local, state and federal agencies have been Alluvial aquifers are associated with areas bordering compiling information about groundwater resources for streams and rivers. Alluvium is a general term for the un- many years to recognize, understand and track trends and consolidated sediments (sand, gravel, silt and clays) de- to inform decisions about management of the resource. In posited by streams in river valleys. Alluvial deposits range 2012, a Master Groundwater Well Inventory was estab- in thickness from a few feet to as much as 300 feet. Depth lished with support from the State Water Plan Fund to water is typically shallow and water stored in alluvial (SWPF), and is maintained at the Kansas Geological Sur- aquifers is usually directly connected to the stream. vey (KGS). This inventory provides an online central data Where hydraulically connected, a distinction usually is not repository for all the primary groundwater data sets in the made between alluvial aquifer and the underlying High state. Well completion logs, water rights information, an- Plains aquifer. nual water use and water well level data are accessible at the Kansas Master Ground-Water Well Inventory website. Groundwater level declines in many stream valleys and Secure, Protect & Restore Kansas Water 19 SECTION 2: STATEWIDE WATER ASSESSMENT - WATER SUPPLY associated alluvial aquifers have separated the intercon- Since 2007, the KGS, supported by the KWO, has hourly nection with the stream and groundwater no longer pro- data in three index wells in the northwest, west central and vides baseflow into the stream. For example, in portions of southwest to gain a full understanding of the aquifer con- the Pawnee, Walnut, Smoky Hill, Arkansas and Solomon ditions, including recovery patterns when no irrigation is rivers the groundwater no longer feeds the streams, and occurring. surface flows are intermittent, occurring only after large precipitation events or during releases from upstream res- Development of the Ogallala portion of High Plains aqui- ervoirs. fer is mature; most of the region is closed by order of Chief Engineer to new water right appropriations, or effec- Groundwater recharge rate studies are useful in defining tively closed through safe yield rules and regulations of safe yield criteria for alluvial aquifers. An example is a Groundwater Management Districts. study of the Lower Arkansas-Ninnescah River Alluvial aquifer from north of Wichita to Arkansas City and the The High Plains aquifer, particularly the Ogallala portion, Ninnescah River from Clearwater to its confluence with has had long term declines in most regions due to wide- the Arkansas River. spread irrigation development and pumping. High Plains Aquifer A 2010 model of the Southwest Kansas GMD 3 region indicated groundwater pumping caused a nearly 30% de- In Kansas, the Ogallala, Great Bend Prairie and Equus crease in aquifer storage from pre-development to 2007, beds are the primary aquifers that form the High Plains for an average decline of roughly 70 feet. As groundwater aquifer. Where interconnected, the alluvial aquifers are levels declined, eventually there was a loss in the ground- also considered part of the High Plains aquifer. Composed water discharging to streams. primarily of silt, sand, gravel and clay, from rock debris washed off the Rocky Mountains and other sources, the Droughts in southwest and south central Kansas in 2011 High Plains aquifer lies beneath eight states, covering ap- and throughout the State in 2012 led to increased irrigation proximately 174,000 square miles; in Kansas it includes pumping. Drought is persisting into early 2013. Until the 30,500 square miles. drought conditions end, steep declines in the Ogallala aq- uifer are expected to continue. The water level declines in In 2000, an estimated 21 million acre feet of water was southwest Kansas from 2011 to 2012 averaged just over 4 pumped from the High Plains aquifer eight state region. In feet; the five (2007 to 2012) year cumulative declines for Kansas, an estimated 4.4 million acre feet of water was the region average 13.24 feet. This region has had the larg- removed from the High Plains aquifer, 2.4 million acre est declines. It is also the region that has the heaviest with- feet from the Ogallala portion. In contrast, the average an- drawals, reflecting the greater aquifer storage. nual recharge to the Ogallala aquifer in Kansas is estimat- ed at 0.72 million acre feet. Dakota Aquifer The Ogallala aquifer is the largest component covering the The Dakota aquifer underlies most of the western two western third of the state. The eastern extension is formed thirds of the state. Thirty six counties in the state have wa- by younger sediments deposited during the Ice Ages: the ter rights permitted in the Dakota aquifer as a sole or par- “Great Bend Prairie” aquifer in Stafford, Edwards, Pratt, tial component. The Dakota aquifer is developed as a wa- Kiowa and parts of other counties, and the “Equus beds” ter supply where fresh (<300 mg/L total dissolved solids) aquifer in McPherson, Reno, Harvey and Sedgwick coun- or only slightly saline, and other freshwater is not more ties. easily available. In north central, central and parts of the southwest, the aquifer has substantial freshwater supplies. The High Plains aquifer is highly variable. The hydraulic conductivity, or how easily water moves through the aqui- In 2011, 2,237 wells reported active use of the Dakota aq- fer, varies from less than 25 to over 200 feet/day. Depth to uifer. Use of the Dakota aquifer is highest in southwest water varies from less than 25 to 50 feet in the Equus Kansas (~86% of reported total use), primarily for irriga- Beds, to over 350 feet in Haskell County, based on meas- tion. Most of these wells are where the Dakota underlies urements from 2010 to 2012. Southwest Kansas has the the High Plains aquifer. Estimated annual average with- greatest saturated thickness with over 300 feet still occur- drawals of 117,000 acre feet/year occurred between 2006 ring in Seward and Stevens counties. West central Kansas and 2010. Although the total amount of water withdrawn averages less than 50 feet of saturated thickness. from the Dakota is a relatively small percentage, new con- 20 Secure, Protect & Restore Kansas Water SECTION 2: STATEWIDE WATER ASSESSMENT - WATER SUPPLY struction of High Plains aquifer wells often is completed in variable both in yield and transmissivity. Sustainable yield both the High Plains and Dakota aquifers, so use of the is difficult to estimate as little is known of the aquifer hy- aquifer is increasing. There are an estimated 11,000 do- drologic properties or its response to pumping. There con- mestic wells screened at least partially in the Dakota. Most tinues to be development of the glacial drift aquifers, par- of these are in north-central Kansas. Large areas of the ticularly in Jefferson and Atchison counties in northeast Dakota aquifer are saline with concentrations that exceed Kansas. Geologic mapping of this region (due 2014), will 10,000 mg/L total dissolved solids. Other water quality further define the hydrologic resources. Chemical quality concerns with the Dakota include fluoride, arsenic, nitrate, is generally hard, but suitable for most uses. Elevated ni- uranium, and radioactivity from radium isotopes and alpha trate (>10 MCL) is a concern in some of these areas. particles. Minor Aquifers Ozark Plateau Aquifer System The Wellington aquifer, part of the Sumner Group aquifer, The Ozark aquifer system consists of the Ozark aquifer occurs in eastern Sedgwick and western Butler Counties in and the overlying Springfield Plateau aquifer, with a dis- extensively fractured shales of the Permian aged Welling- continuous confining unit separating the two aquifers.
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