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Table of Contents

Abstract

Introduction

Geography

Geology

Ground Water

Water Bearing Formations

Well Records

Well Logs

References

Plates

Ground Water, continued

Utilization of Ground Water

Domestic and Stock Supplies

The domestic use of water generally includes drinking, cooking, washing, and in some cases the disposal of sewage. In Thomas County the ground waters are generally satisfactory for all domestic purposes (see "Quality of Water"), and ground water in sufficient quantity for such uses can be obtained at nearly any locality in the county.

Public Supplies

Brewster--The city of Brewster, located in the west-central part of the county, obtains its water supply from two drilled wells (nos. 69, 70). Water is pumped from these wells to an elevated steel storage tank having a capacity of 50,000 gallons. The daily capacity of the system was reported to be 30,000 gallons, but the average daily consumption is not known. Data on the wells are given in table 9, and a chemical analysis of the water is given in table 5. The water is of good quality and is not treated.

Colby--Colby, the county seat and largest city in the county, obtains its water supply from five drilled wells (44-48) at the west edge of town. Data concerning these wells are given in table 9, and a chemical analysis of the water is given in table 5. Two of the wells are equipped with turbine pumps and the remaining three with double action plunger pumps. Storage is provided in a reservoir at ground level having a capacity of 500,000 gallons and an elevated tank holding 70,000 gallons.

According to O.L. Day, the largest consumption of the year occurs during the months from June to September. The greatest monthly consumption was in August, 1939, when 21,000,000 gallons was pumped. About 115,500,000 gallons, or 845 acre feet, was pumped during 1941. If the annual recharge is 18.3 acre feet (page 33) per square mile this would amount to the recharge from about 25 square miles.

Rexford--The city of Rexford, located in the northeastern part of the county, obtains its water supply from two drilled wells (26,27) at the east edge of town. Water is pumped from the wells to an elevated storage tank having a capacity of 50,000 gallons. Data on the wells are given in table 9, and a chemical analysis of the water is given in table 5.

Irrigation Supplies

The yields of irrigation wells in Thomas County range widely. In 1943, pumping tests were conducted on four of the seven irrigation wells in the county equipped with pumps, by Howard Palmer and Allan Graffham of the Division of Water Resources of the Kansas State Board of Agriculture in cooperation with the State and Federal Geological Surveys. The results of these pumping tests are given in table 4, and the recovery curves are shown in figure 10. It will be noted that the yields of these four wells ranged from 295 to 1,021 gallons a minute and their specific capacities ranged from 11.2 to 56.5. The average specific capacity of the four wells was 30.8.

The most extensive well-irrigation area in Kansas lies due south of Thomas County in the Arkansas River valley and the shallow water basins of Scott, Finney, and Grant counties. In Hamilton and Kearny counties (McLaughlin, 1943, p. 89) the range in yield of eight single-well pumping plants was 480 to 1,280 gallons a minute. The specific capacities of these wells ranged from 8.5 to 55.2 and averaged 20.9. In Finney and Gray counties (Latta, 1944, p. 107), the range in yield of 17 single-well pumping plants was 348 to 1,770 gallons a minute, and the specific capacities ranged from 10 to 141 and averaged 46.9. Although the yields of the four wells tested in Thomas County are slightly lower than in the large irrigation areas to the south, they nevertheless are in the same general range. Also, the specific capacities of these wells compare favorably with wells in Hamilton and Kearny counties but are appreciably lower than the specific capacities of irrigation wells in Finney and Cray counties.

A comparison of depth and diameter of the irrigation wells in Thomas County with those farther south shows that the Thomas County wells are generally deeper and of somewhat smaller diameter. In Hamilton and Kearny counties (McLaughlin, 1948, pp. 92, 98) 77 wells were less than and 19 more than 100 feet in depth, and the prevalent diameters were 16 and 18 inches. In Finney and Gray counties (Latta, 1944, pp. 111, 112) 170 wells were less than and 59 more than 100 feet deep, and the prevalent diameters were 15, 16, 18, and 20 inches. In Thomas County two of the irrigation wells are less than 100 feet in depth and 7 are more than 100 feet. The diameters of the nine wells are: two wells, 14 inches; five wells, 16 inches; one well, 18 inches; and one well, 32 inches.

In 1914 a well-irrigation plant was installed at the Colby experiment station at the southwest corner of the city of Colby, but the irrigation wells were later abandoned. Embert Coles has generously furnished data from his files concerning the operation of this plant. The plant consisted of two wells, 12 feet apart, equipped with 534-inch cylinder pumps powered by an eight-horsepower Fairbanks-Morse engine. The log of the well is given at the end of this report (no. 30). The depth to water level was reported to be 112 feet in 1914, and 112.5 feet in November, 1919. On May 18,1945, the east well was uncovered and measured by George S. Knapp and J. B. Kuska. The depth to water was found to be 114.8 feet below the 1919 measuring point. During 1919 the pumping plant was operated for 318 hours at a rate of 97.8 gallons a minute, which produced about 5.7 acre-feet of water. The cost of fuel and oil per acre foot of water pumped was reported to be $5.62, but it was impossible to determine the cost of plant depreciation, repair, and operation of equipment, so the total cost of the water per acre foot is not known. Although the cost of fuel probably could be lowered by using more economical pumping equipment, the fuel cost will be relatively high where the pumping lift (static water level plus draw-dawn) is great.

Possibilities of Future Development of Irrigation Supplies

The depth to water level and type of water-bearing material determine in part the cost of drilling and pumping. Some wells that may encounter relatively fine-grained material will have relatively small yields. Gravel packing may increase the yield of such wells but it also adds to the cost of construction.

For the purpose of more detailed description, Thomas County may be divided into three general areas. In the order of their irrigation possibilities these are (1) major valleys in northeastern and eastern parts of the county, (2) uplands in the northern and eastern parts of the county, and (3) southwestern upland area.

Major valleys in northeastern area--With respect to supply and cost of water, the major valleys in northeastern Thomas County present the most favorable areas for future irrigation development. Plate 2 shows that the depth to water level is less than 50 feet below the valley of South Sappa Creek from near Brewster to the Rawlins County line, and that the depth to water level below the valley of Prairie Dog Creek is less than 50 feet from east of Colby to the Sheridan County line. From north of Colby eastward the depth to water level below the bottom of South Sappa Creek valley is less than 25 feet and under part of the valley the water table stands only a few feet below the surface. Two irrigation wells are in operation along South Sappa Creek and pumping test data are given for one of these wells (14) in table 4. This well, which is equipped with a 6-inch centrifugal pump, yielded 637 gallons a minute with a drawdown of 15.37 feet, and had a specific capacity of 41.4. The total pumping lift to land surface (the water is discharged through an elevated pipe as shown in pl. 4B) was less than 30 feet. Such a well compares favorably with many of the wells in the extensive irrigation areas to the south (p. 50) and to the north in Nebraska. The cross sections (figs. 3 and 4) show that more than 100 feet of saturated water-bearing material occurs below the bottoms of these valleys and above the bedrock floor of Pierre shale. None of the wells now in operation in these valleys (with the possible exception of well 13) penetrates the entire thickness of water-bearing material; thus deeper drilling to the top of the Pierre shale would make available a larger quantity of water. Several thousand acres of land along South Sappa Creek in north-central Thomas County and Prairie Dog Creek near the east county line have suitable topography for irrigation and wells can be obtained that yield more than 500 gallons a minute with a total pumping lift of 50 feet or less. There are smaller areas having equally good possibilities along the valleys of the South Fork of the Solomon River and the North and South Forks of the Saline River in the eastern part of the county. The character of the water-bearing materials varies in short distances; therefore one or more test holes to determine the character of the sand and gravel are advisable before drilling an irrigation well.

Northern and eastern upland areas--Reference to plate 2 will show that there are extensive areas in northern and eastern Thomas County, in addition to the valley areas, where the depth to water level is less than 100 feet. The cross sections (figs. 3 and 4) show that under the northern, eastern, and central parts of the county there is from 100 to 150 feet of saturated water-bearing material above the floor of Pierre shale. Two of the irrigation wells tested and reported in table 4 are on the upland and intermediate levels in the northeastern part of the county. The static water level in one of these wells was 72.90 feet below the surface and in the other it was 104.32 feet below the surface; they yielded 1,021 and 588 gallons a minute and had specific capacities of 56.5 and 14.0 respectively. One other upland irrigation well north of Colby which was tested had a static water level of 128.01 feet below the surface, a. yield of 295 gallons a minute, and a specific capacity of 11.2. The data on these three wells indicate a wide range in the characteristics of upland wells in these parts of the county.

Quantities of water sufficient for irrigation can be obtained at many places on the upland and intermediate levels of northern, eastern, and central Thomas County. The pumping lifts will range generally from slightly less than 100 feet to more than 150 feet. Wells should be drilled through the entire thickness of the water-hearing material to the Pierre shale. The cost of construction and of pumping water from this depth, in addition to other factors, should be considered in any contemplated irrigation undertaking. Owing to the lateral variation in the water-bearing material of this area, one or more test holes should be put down before an irrigation well is drilled.

Southwestern upland area--As shown on plate 2, the dept to water level under nearly all of southwestern Thomas County is more than 100 feet and at some places it is as much as 200 feet. Cross section B-B' in figure 3 and cross section F-F' in figure 4 show that the thickness of saturated water-bearing material under this area is much less than in other parts of the county - in fact at some places there is less than 10 feet of saturated material above the Pierre shale. Although an adequate quantity of water is available for domestic or stock wells at most places in the southwestern part of the county, yields sufficient for irrigation purposes could be obtained at only a few places. The great depth to water level and relatively small quantities of water available under the uplands of the southwestern part of the county make this area generally unsatisfactory for well irrigation.

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