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

The present water supply in Mammoth Cave National Park is obtained from a group of three springs (appropriately named Three Springs) on Flint Ridge about 6,000 feet northeast of park headquarters, from Bransford Spring about 2,500 feet northeast of Three Springs, and from a deep well at Bransford Spring (fig. 71). Blair Spring, located about 3,000 feet east of Bransford Spring, was used as an emergency supply for about 5 weeks in the summer of 1962 and during at least one other summer season. During the critical period in August 1962, additional water was hauled by truck from Adwell Spring, about 8,000 feet east of Three Springs. Three Springs and Bransford, Blair, and Adwell Springs, along with several other springs and seeps, drain the perched aquifer in the Haney Limestone Member of the Golconda Formation on Flint Ridge. The deep well at Bransford Spring obtains water from the basal aquifer at or near the level of the Green River.

Minimum flows during the critical period in August 1962 and observed minimum flows of presently used sources of water are summarized in the following table.

The flow from the springs is piped by gravity to storage tanks at Three Springs and Bransford Spring. Water from the deep well is pumped into the storage tank at Bransford Spring. Water from Blair Spring was pumped from a basin at the spring through a plastic pipeline on top of the ground to the storage tank at Bransford Spring.

Each of the storage tanks at Three Springs and Bransford Spring has a capacity of 50,000 gallons. Water from these tanks is pumped to the 50,000-gallon tanks on top of Flint Ridge, about 7,000 feet north east of park headquarters. Two additional tanks, each having a capacity of 500,000 gallons, have been constructed (1963) at this site to increase storage from 200,000 gallons to 1,200,000 gallons. From the storage tanks on Flint Ridge water is supplied by gravity flow to park headquarters, Mammoth Cave Hotel, staff living quarters, service station, and other facilities.

During August 19-25, 1962, 590,570 gallons (Perry E. Brown, Supt., Mammoth Cave National Park, written commun., 1963) was used at an average daily rate of 84,370 gallons. The major supply during the critical period in August was 45 gpm (gallons per minute) or 64,800 gpd (the Bransford well was pumped 24 hours per day). This supply was supplemented by water hauled from Adwell Spring by tank truck at the rate of about 17,000 gpd; the total supply was thus 81,800 gallons. The difference between the demand, 84,370 gpd, and the supply, 81,800 gpd, is 2,570 gpd that was obtained from storage in the four 50,000-gallon tanks.

August 1962 was thus a very critical period for the present water system at Mammoth Cave National Park. Even with conservation measures, the demand exceeded the supply at the rate of nearly 3,000 gpd. However, the problem could have been considerably worse if the drought had been more serious, if the pumping equipment had failed, or if a fire had occurred.

As shown previously, hydrologic conditions were not extreme during August 1962; there have been at least three more severe August droughts in the period 1915-22, 1925-62. A failure of equipment at Bransford well would reduce the supply by 14 gpm, or 20,160 gpd. The amount of water needed for fire fighting is difficult to estimate, but the Kentucky Inspection Bureau's rating for eighth-class protection is 500 gpm for 4 hours, or a total of 120,000 gallons.

The addition of the two 500,000-gallon storage tanks has partially alleviated the deficiency of the present water supply but additional supplies are still needed, With the same supply (Bransford Spring, Three Springs, and Bransford well) and demand that existed in May-September 1962 but including the additional storage, the emergency sources (Blair and Adwell Springs) would still be needed. Average daily use was estimated to increase from 60,000 gpd at the end of May to 85,000 gpd in the last week of July and remain constant thereafter to the end of the season. It was also assumed that Bransford well would be pumped continuously at the rate of 14 gpm unless storage was full. Storage decreased from 1,200,000 gallons June 26 to 136,000 gallons August 22 and was completely depleted before August 29. This decrease means that some or all of the emergency methods would have to be initiated again so that either the supply would be increased or the demand would be decreased.