A Review Of Ground-Water Resources in the Havana Lowlands Region From the Illinois State Water Survey
A Division of the Illinois Department of Energy and Natural Resources – Springfield, Illinois
The ground-water resources in the Havana Lowlands are among the most plentiful in the State. Water is stored and transported underground in unconsolidated (as opposed to consolidated or bedrock) sand and gravel deposits.
These sand and gravel "aquifers" have two origins.
- First, during the time of the retreat of the last great ice age (approximately 12,000 to 15,000 years ago) sand and gravel deposits were washed into ancient river valleys. These valleys were filled, or buried, with sands and gravels which, today, form the aquifers where ground water is stored and transported. The most prominent of these ancient buried valleys is the Mahomet Valley, a tributary of the Teays Valley, which is believed to be the preglacial ancestor of the present Ohio River. The Mahomet Valley enters Mason County from the east where is joins a number of small-drained into the ancient Mississippi River Valley, which corresponds generally to the present Illinois River. The presence of these buried valleys provides an ideal environment for abundant ground-water resources.
- The second source for sand and gravel deposits is the outwash from the present day Illinois River. These deposits are in hydraulic connection with those in the buried valleys, so they are considered to be one aquifer system. Ground water in that aquifer system generally moves from the east-northeast to west-southwest toward the Illinois River. The river is the major point of discharge for the ground water in the Havana Lowlands.
Jake Wolf Memorial Fish Hatchery
The thickness of the sand and gravel deposits that are saturated with water ranges from about 60 feet near the Illinois River to as much as 180-200 feet in the vicinity of San Jose. The deposits are thickest in the areas where the ancient valleys were the deepest and where the maximum amount of glacial filling occurred.
In the western half of the region (roughly following a line through South Pekin, Green Valley, Easton, Kilbourne, and Chandlerville) ground-water recharge is estimated to be 490,000 gallons per day per mile square, or about 30 percent (10.3 inches per year) of average annual precipitation.
To the east of that line, recharge is estimated at 270,000 gallons per day per mile square, or about 16 percent (5.7 inches per year) of average annual precipitaion.
The water yielding characteristics of the sand and gravel deposits in the Havana Lowlands are good to excellent. The transmissivity (the capacity of a formation to transmit ground water) ranges from about 200,000 to 270,000 gallons per day per foot (gpd/ft) in the eastern part of the region and from about 560,000 to as much as 1,250,000 probably averaging about 0.10. These hydraulic characteristics allow individual wells to be pumped at high rates for extended periods of time. Wells intended for high capacity use are usually pumped at rates from 600 to 1,500 gallons per minute and generally range in depth from about 60 to 140 feet. They are equipped with lengths of commercial well screen and artificially placed gravel pack appropriate for the intended use rate and specific site conditions.
The Havana Lowlands area has been extensively developed for agricultural irrigation since about 1960; at that time there were an estimate 11 irrigation systems in use. Now there are more than 800 systems in use with about 100,000 acres irrigated. Ground-water withdrawals for irrigation in the region are estimated at about 55 million gallons per day (mgd) on an annual basis in 1986. Another 32 mgd were withdrawn for public water supply and industrial uses. Ground-water use in the area in 1986 amounted to about 25 percent of the potential yield of 350 mgd as estimated be Walker et al., in 1965.
*The ground-water resources in the region are capable of supporting continued expansion of agricultural irrigation and other beneficial uses of ground water as the resource development is well planned and managed.