Geological Survey Water-Supply Paper 1475-Q Present and Future Water Supply for Mammoth Cave National Park, Kentucky

The purpose of this progress report is to summarize the available information on the quantity and quality of all sources of water in the area and to evaluate the information for use by National Park Service engineers and planners. Specifically, the report presents information to answer the questions: (1) Where can additional water supplies be obtained, (2) what is the chemical quality and dry-weather yield of the potential sources, (3) what is the type and extent of present or potential pollution of the sources, (4) how are the several potential supplies interrelated, and (5) which of the potential supplies can be developed to meet present and future needs?

Mammoth Cave National Park, in south-central Kentucky (fig. 71), is one of the best known national parks in the Eastern United States; it operates on a year-round basis for a steadily increasing number of visitors. For the past several years the water system of the park was not adequate to supply all the water needs during the period of peak visitor load (late July and August), and water-conservation measures or water hauling was resorted to during the critical period. Because of the increased water use and because the Mission 66 program includes plans for the expansion of the overall facilities at Mammoth Cave National Park, a water supply much larger than that now developed is needed.

FIGURE 71.—Physiographic features, streams, wells, and springs in the Mammoth Cave area, Kentucky. 1, Sand Cave Spring; 2, Echo River; 3, Styx River; 4, Eaton Valley well; 5, Three Springs; 6, Bransford well; 7, Bransford Spring; 8, Blair Spring; 9, Pike Spring; 10, Spring at CCC No. 1; 11, Collins Spring; 12, Cooper Spring; 13, Adwell Spring; 14, well at CCC No. 1; 15, Union City well; 16, Chaumont well. (click on image for an enlargement in a new window)

At the request of the National Park Service, an investigation of the water resources of Mammoth Cave National Park was undertaken by the U.S. Geological Survey in 1961. In addition to an overall appraisal of the hydrology of the area, the study includes an evaluation of the dry-weather yield of the developed sources of supply and the quantity, quality, and dependability of all potential sources of supply.

WATER REQUIREMENTS

The increase in the number of visitors to Mammoth Cave National Park in the past several years and the estimated range of attendance to 1980 under the Mission 66 program are shown in figure 72. Any water supply that is planned must be able to meet not only the present water needs of the park but also future needs.

FIGURE 72.—Increasing numbers of visitors and increasing per-capita water use require additional water-supply development for Mammoth Cave National Park. (click on image for an enlargement in a new window)

The greatest demand for water is during June through September because of increased visits during the vacation months. Unfortunately, the period of greatest demand is also the period when the available supply is nearing its annual low. The maximum use recorded was 623,000 gallons during the week of July 25-31, 1962 (Perry E. Brown, Superintendent, Mammoth Cave National Park, written commun., 1963), or an average daily rate of 89,030 gallons. On a peak day, June 27, 1962, 97,000 gallons were consumed by park visitors (Glenn C. Farrar, Engineer, Mammoth Cave National Park, written commun., 1962).

The existing supply was inadequate during the drought of August 1962, and it was necessary to supplement the supply by pumping from Blair Spring and hauling water by truck from Adwell Spring (fig. 71). Signs asking users to conserve water were posted.

Long-term flow records of the developed supply are not available to evaluate the frequency of a drought of this magnitude. The mean discharge of the Green River during August 1962 is an approximate measure of the severity of the drought as it affects the park water supply during the period of greatest demand. The disadvantage of using Green River flow as an indicator is that the flow represents an integrated resultant of that part of the hydrologic cycle occurring in several thousand square miles of central Kentucky, whereas the present supply of Mammoth Cave comes from a perched aquifer that has a recharge area of only a few square miles. An advantage of using the mean flow of the Green River during August as an indicator is that the flow during August not only reflects the precipitation during August but the carryover effect from antecedent precipitation. Records for the gaging stations on Green River at Munfordville, Brownsville, and Calhoun were correlated to give an estimated mean August discharge at Brownsville for each missing year of record during the years 1915-22, 1925-62. This list of actual or estimated mean August discharges of Green River at Brownsville for the 46-year period shows that a mean August flow of about 230 cfs (cubic feet per second) or 148 mgd (million gallons per day) has a recurrence interval of about 50 years, and that the 1962 mean August discharge of 367 cfs or 237 mgd has a recurrence interval of about 12 years. This recurrence interval in no way implies that, once an August mean discharge of 367 cfs occurs, it will not recur for another 12 years. It means that on the basis of past experience at Brownsville an August mean discharge of 367 cfs or lower can be expected to occur on an average of once every 12 years. If the flow at Brownsville is a valid indicator of the present water supply at Mammoth Cave, the deficiency experienced in 1962 can be expected to be equaled or exceeded every 12 years. However, it must be emphasized that the use of this indicator is an approximation only, owing to the large drainage area of the Green River being compared to the small recharge area of the perched aquifer and the small watersheds in the park.

On the basis of the estimated increase of visitors to the park to 1980 and the expanded facilities, the water consumption by 1980 will be at least 200,000 to 250,000 gpd (gallons per day) during the summer season. The present supply is not capable of furnishing this amount of water during the summer seasons.

AVAILABLE WATER INFORMATION

In addition to the data obtained during the present investigation, this report is based in part on studies of the geology and hydrology of the area in 1953 by R. F. Brown.¹ Also available are intermittent gage-height and discharge measurements of outlet streams of Mammoth Cave since 1953, daily staff-gage readings of Green River at Mammoth Cave since 1938, continuous record of the water level in Mammoth Cave since 1958 and of Green River since 1960, chloride determinations of water from Green River at Munfordville since 1950 and at Mammoth Cave since 1958, periodic and intermittent chemical analyses of water from Styx, Echo, and Green Rivers since 1953, and continuous record of water level in three deep wells at Mammoth Cave since 1953. Gaging-station records are published in reports of the U.S. Geological Survey for the Green River at Munfordville (1915-22, 1927-31, 1936-37, 1937-63), at Mammoth Cave (1938-50), and at Brownsville (1924-31, 1936-37, 1938-63). The above data were obtained by the U.S. Geological Survey in cooperation with the Kentucky Geological Survey and the National Park Service.

---

¹Brown, R. F., 1953, Reconnaissance of the geology and ground-water hydrology in the vicinity of Mammoth Cave National Park, Kentucky: U.S. Geol. Survey adm. rept. to Nat. Park Service, unpublished data, 16 p., duplicated.

---