The Ohio River Alluviam Aquifer
Louisville, Kentucky

by

Chris Jung

GO 571 Geohydrology, Emporia State University

Figure 1. Photo courtesy of Greater Louisville Convention & Visitor Bureau.


Introduction
Hydrology/Geology
Climate
Recharge
Water Resources
Susceptibility to Contamination
Conclusion
References


Introduction

The Ohio River Alluvium aquifer is an important resource for the citizens and industries of Louisville, Kentucky. The study area is located in north Jefferson County, Kentucky and consists of approximately 39,600 acres. The Ohio River Alluvium aquifer is bounded by the Ohio River and terraces deposits. The land surface in the river valley ranges from 383 to 440 feet above mean sea level with occasional terraces as high as 460 feet. Most of the area is used for industrial or residential purposes (USGS, 1986).

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Hydrology/Geology

The study area lies within the Ohio River Alluvium physiographic region of Kentucky. Deposits in the county include limestone, shale, dolomite, lacustrine, and alluvial deposits. The Ohio River Alluvium is primarily made up of Pleistocene glacial outwash material and unconsolidated alluvium, which consists of sand, gravel, clay, and silt. Regionally, the lithology is comprised of a 5 to 45-feet thick layer of clay, silt, and fine sand that overlays sand and gravel containing discontinuous lenses of clay. Beneath the aquifer are relatively tight shale and limestone bedrock (USGS, 1986).

Figure 2. Image adapted from Kentucky Geological Survey geospatial data.

Many aquifer tests have been conducted on the Ohio River aquifer, and the derived estimates for transmissivity is approximately 121,000 (gal/d)/ft with a storage coefficient of 0.0003. Based on United States Geological Survey (USGS) gage data from this section of the Ohio River, the average annual flow rate is 116,800 cubic feet per second; the average thickness of the aquifer is approximately 100 feet; and the groundwater flow direction is toward the Ohio River(USGS, 2006).

Figure 3. Basic lithology of the aquifer.

According to the Soil Survey of Jefferson County, Kentucky, the area of study is situated in the Wheeling-Weinbach-Huntington association, which consists of level to sloping soils on terraces and bottoms along the Ohio River. The soils in this area formed a mixed sediment that washed from the upper part of the Ohio River basin.

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Climate

The Midwestern Climate Center (MCC) in Champaign, Illinois was consulted to determine the climate condition for Jefferson County, Kentucky. According to MCC data from the monitoring station at the Louisville WSO Airport Station, January is the month with the lowest mean temperature (24.9 degrees Fahrenheit), and July is the month with the highest mean (87.0 degrees Fahrenheit). Typically, a wet season exists between November and May with May having the highest mean precipitation (4.88 inches) and October having the lowest (2.79 inches). Snowfall typically occurs between October and April, with January and February having the highest mean snowfall accumulation of 5.1 and 4.5 inches, respectively (MCC, WEB).

. Figure 4. Graph that shows the daily precipitation for Louisville from May 1, 2006 to May 1, 2007 (USGS, 2007). .

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Recharge

The Ohio River is hydraulically connected to the Ohio River Alluvium aquifer. Small streams in the area also influence the aquifer but to a much lesser degree than the Ohio River. Recharge to the aquifer occurs through flow from small streams, valley walls, precipitation, and infiltration from the Ohio River during high river stages and periods of high groundwater withdrawal. Discharge of the aquifer occurs to the Ohio River and production wells (Unthank, 1998).


Water Resources

The Ohio River Alluvium is the most dependable source of groundwater for Jefferson County. Domestic wells drilled in the alluvium are generally drilled to a depth of 100 feet below ground surface and can produce approximately 1,000 gallons of water per minute. Of the domestic wells located in the upland region outside of the alluvium, less than half produce adequate amounts of water for domestic purposes and often suffer during dry periods (Davidson, 2004).

Water is often described in terms of its “hardness,” or the degree to which lather produces when using soap. Hard water primarily results from an abundance of magnesium and calcium. The groundwater throughout Jefferson County is typically classified as hard to very hard. The magnesium and calcium in the groundwater are likely due to leaching from carbonate and sedimentary rocks in the region (Davidson, 2004).

Figure 5. This graph is a compellation of hardness in four aquifers in Kentucky (DOW, WEB).

The Ohio River Alluvium is the most dependable source of groundwater for Jefferson County. Domestic wells drilled in the alluvium are generally drilled to a depth of 100 feet below ground surface and can produce approximately 1,000 gallons of water per minute. Of the domestic wells located in the upland region outside of the alluvium, less than half produce adequate amounts of water for domestic purposes and often suffer during dry periods (Davidson, 2004).

Figure 6. Adapted from KGS geospatial data.
Note alluvium is located in a high sensitivity area.

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Susceptibility to Contamination

According to a groundwater sensitivity map generated by Kentucky’s Groundwater Branch, the study area is considered to be located in a “high sensitive” area. Groundwater flow in coarse, unconsolidated material has the potential to move contaminants very rapidly. Locally, Louisville has many industrial facilities (see Figure 7) located within the recharge zone for this aquifer, which poses a potential source for contamination. The presence of a discontinuous layer of clay is present from the surface elevation to approximately 45 feet below land surface. This clay layer provides some protection to the aquifer from surface spills (Ray, 1994).

Figure 7. Image obtained from EPA Enviromapper website.
Several facilities containing hazardous materials are located in the alluvium.

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Conclusion

Groundwater quality continues to be a major consideration in growing communities such as Louisville. In general, groundwater water supply systems are significantly less costly to operate and maintain than are surface water systems. Once aquifers become contaminated they are difficult and expensive to remediate. Data acquired from groundwater analysis in areas like Louisville should be used to shape current and future regulatory policy and to inform regulatory agencies, municipalities, industries, and individuals of areas that are sensitive to contamination so that appropriate land use practices may be followed to ensure water sources are protected for future use.

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References

EPA Enviromapper, World Wide Web URL: http://www.epa.gov/enviro/html/em/index.html [Retrieved on April 25, 2007].

Davidson, B., Carey, D., Greb, S., Generalized Geologic Map for Land Use Planning: Jefferson County, Kentucky. Kentucky Geological Survey, 2004.

Kentucky Division of Water, World Wide Web URL: http://www.water.ky.gov/ [Retrieved on April 21, 2007].

Kentucky Geological Survey (KGS), World Wide Web URL: http://www.uky.edu/KGS/ [Retrieved on April 22, 2007].

Midwestern Regional Climate Center, World Wide Web URL: http://mcc.sws.uiuc.edu/ [Retrieved on April 18, 2007].

Palmquist, J. R. and Hall, F.R. 1960. Availability of Ground Water in Bullett, Jefferson, and Oldham Counties, Kentucky. Hydrologic Investigations Atlas HA-22, U.S. Geological Survey, Washington, D. C.

Peck, D.,U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1151-H, World Wide Web URL: http://www.usgs.gov/pubprod/, [Retrieved on April 24, 2007].

Ray, J.A., Webb, J.S., O’dell, P.W. 1994. Groundwater Sensitivity Regions of Kentucky, Kentucky Department for Environmental Protection, Division of Water Groundwater Branch.

Soil Survey of Jefferson County, Kentucky. U.S Department of Agriculture, Soil Conservation Service, 1966. p. 21, 35, & 36.

United States Geological Survey. USGS 03294500 OHIO RIVER AT LOUISVILLE, KY. World Wide Web URL: http://waterdata.usgs.gov/nwis/, [Retrieved on April 22, 2007].

Unthank, M.D., Nelson, H.L. 2006. Summary of Available Hydrogeologic Data for the Northeast Portion of the Alluvial Aquifer at Louisville, Kentucky, Open File Report 2006-1146, USGS, p. 9.

Unthank, M.D., Hydrogeology and Simulation of Ground-Water Flow in the Ohio River Alluvial Aquifer Near Carrollton, Kentucky, USGS Report 98-4215, 1998, p. 19.

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This web page was created to fulfill the requirements for GO 571 Geohydrology at Emporia State University.
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This page was created on 4/24/07.