Ground-Water Conditions in the Smoky Hill Valley in Saline, Dickinson, and Geary Counties, Kansas
Authors: Latta Bruce F. 
Published: January 2025

This report gives the results of an investigation of ground water in the Smoky Hill Valley and its major tributary valleys in Saline, Dickinson, and Geary Counties, in central Kansas. Situated in this area are the cities of Salina, the chief distribution center for the central Kansas area, Abilene, Junction City, and numerous smaller towns, the cantonment areas of the Fort Riley Military Reservation and Camp Phillips, and the Smoky Hill Army Air Base. Agriculture is the dominant enterprise of the area and most urban industries are related to the agriculture.
The strata in the central Kansas region dip gently to the west, but have been beveled by an erosional plain that slopes eastward, Smoky Hill River and its major tributaries have cut below this old plain and lire now flowing in rather wide, flat-bottomed valleys that are underlain by thick unconsolidated alluvial deposits of Quaternary age. These deposits are the most important source of water in the area.
The bedrock formations that underlie the unconsolidated alluvial deposits and form the uplands bordering the valleys include sedimentary rocks of Permian and Cretaceous age. East of Abilene the bedrock consists of alternating beds of limestone and shale of the Wolfcampian Series (Permian). West of Abilene the Wellington formation (Permian) underlies the alluvial deposits and forms the uplands. The Wellington formation consists chiefly of shale, but includes also thick beds of gypsum and thin beds of impure limestone. Clay, shale, and thick lenticular beds of sandstone of the Kiowa shale (Cretaceous) unconformably overlie the Wellington formation along parts of the Smoky Hill and Saline Valleys in Saline County.
Dune sand, ranging from a featheredge to about 40 feet in thickness, covers an area of about 20 square miles along the north side of Smoky Hill Valley between Abilene and Solomon. Stream-laid terrace deposits of Pleistocene age underlie the dune sand and rest unconformably on shale, limestone, and gypsum of the Wellington formation and the upper part of the Wolfcampian Series. The terrace deposits are 50 to 65 feet thick near the valley and thin to a featheredge at the north. They consist principally of overlapping lenses of unconsolidated silt, sand, and gravel. Domestic and stock wells derive water of excellent quality from the terrace deposits. There are no large wells in this area, but test drilling indicates that in some places the sands and gravels are sufficiently thick and coarse to supply several hundred gallons of water a minute to properly constructed wells.
The only spring (Sand Springs) of importance in the Smoky Hill Valley area is on the north bank of Smoky Hill River about 2.5 miles west of Abilene and is the source of the Abilene water supply. Water is discharged at the spring from a solution opening between bedding planes in Permian limestone (Herington limestone member of the Nolans limestone). The limestone through which the water issues is about 7 feet thick and extends only a short distance northward beneath the water-bearing terrace deposits. Water moves from the terrace deposits into fractures and solution openings in the limestone and is discharged at the spring. The flow of the spring ranges from less than 900 gallons a minute during periods of low rainfall to about 1,200 gallons a minute during wet periods.
All large water supplies in this area, with the exception of the Abilene supply, are obtained from wells that tap the Quaternary alluvial deposits beneath the valley plains. The logs of 93 test holes drilled by the State Geological Survey in Smoky Hill Valley and its tributary valleys and the logs of 30 test holes and 23 wells obtained from city officials and private drilling companies are included in this report. These data are shown graphically by 14 cross sections, nine of which are of Smoky Hill Valley and one each of Republican, Solomon, Saline, Mulberry, and Dry Creek Valleys. The alluvium in these valleys consists of unconsolidated clay, silt, sand, and gravel. The finer materials commonly occur in the upper part and the coarser materials in the lower part. Most of the large wells penetrate the entire thickness of alluvium.
Smoky Hill Valley in the area considered is about 72 miles long and 1 to 5 miles wide. It is underlain by alluvium ranging in thickness from less than 30 to more than 90 feet. The greatest thickness of alluvium, 94 feet, was encountered about 1 mile southeast of Mentor in southern Saline County. The yields of wells that tap alluvium in Smoky Hill Valley range from a few gallons a minute for small domestic and stock wells to 1,500 gallons a minute for larger wells. Moderate to large supplies of water are available from wells in most places in Smoky Hill Valley in this area. The Cities of Assaria, Salina, Solomon, Enterprise, and Chapman obtain their water supplies from wells in Smoky Hill Valley.
Alluvium in the part of the Republican Valley in Geary County ranges in thickness from a few feet to 82 feet, the average being about 45 feet. The sands and gravels in the lower part of the alluvium furnish large supplies of water to wells that tap them. The Cities of Milford and Junction City, the Cavalry Replacement Training Center of the Fort Riley Military Reservation, and Fort Riley obtain water from these deposits. The yields of the wells range from 150 to 1,200 gallons a minute.
Nine test holes drilled in Solomon Valley in Saline County penetrated 44 to 65 feet of alluvium. No large wells have been drilled in Solomon Valley in this area, but the test drilling indicates that wells having moderate to large yields could be developed here. In places, however, the water in the alluvial deposits is too highly mineralized for ordinary uses.
In Saline Valley in Saline County the thickness of alluvium in six test holes ranges from 20 to 92 feet and averages 64 feet. The thickness of alluvium in five test holes drilled in Mulberry Valley, a tributary of Saline Valley, ranges from 36 to 66 feet. No large wells have been drilled in either Saline or Mulberry Valley but the test drilling indicates that moderate to large supplies are available in these valleys.
The alluvium in the valley of Dry Creek, which flows northward along the west edge. of Smoky Hill Valley and is tributary to Mulberry Creek, is a few feet to more than 50 feet thick, It consists principally of silt and clay with thin lenses of sand and gravel at the base. Small supplies of very hard water are obtained from these deposits for farm use.
The use of ground water for irrigation is not extensive in the Smoky Hill Valley area. In 1943 there were only seven irrigation wells in this entire area. Five of these wells were in the vicinity of Abilene and two were in the vicinity of Salina.
Ground waters from the alluvial deposits in the Smoky Hill Valley area are hard to very hard. The hardness of 61 samples analyzed ranged from 274 to 1,980 parts per million. Many of the samples. contained undesirable concentrations of iron. Of 64 samples analyzed for iron, 51 contained more than 0.1 part per million and 32 contained more than 1 part. Some ground waters in the alluvium of Solomon and Smoky Hill Valleys in the vicinity of Solomon are unfit for most uses because of the high concentrations of chloride. Concentrations of chloride in excess of 10,000 parts per million were found in some samples of water taken from the lower part of the alluvium in this area. However, in places the upper waters in the Solomon area are relatively low in chloride.