Jeff C. Fisher
James M. Raab
Kristina M. Boone
Larry C. Brown
Water stored under the Earth's surface is a plentiful, yet precious, resource in most areas of Ohio. Humans greatly affect ground water. However, the availability and quality of this resource are influenced directly by the properties of the geologic formation that holds water. The chemical and physical nature of these formations varies from area to area, creating a wide range of water yields and quality at different depths. This publication contains information about the ground-water resources underlying Scioto County. Its purpose is to help the reader better understand the factors that influence the quantity and quality of ground water. Water resources terminology used in this publication is included in Surface and Ground Water Terminology, Fact Sheet AEX-460, which provides a listing of generally accepted water resource definitions. Fact Sheet AEX-460 and the publication Scioto County Water Resources, AEX-480.73, are available through your county Extension office.
Geologic formations (e.g., sand, gravel, limestone, sandstone) have the ability to receive, store and transmit water. In general, if a formation is capable of yielding enough water to support a well or spring, it is called an aquifer. The material from which the formation originally was made influences its ability to store and transmit water. For example, sands and gravels allow water to flow through easily. By comparison, shale, which originated from compacted layers of mud and clay, generally allows very little water to flow through it unless the shale is highly fractured.
The principal bedrock aquifers in southeastern Ohio, including Scioto County, consist of sandstone and shale, which were deposited about 300 to 400 million years ago during the Paleozoic Era. In most areas, these formations are covered by a thin layer of clay, silt or sand. In general, the bedrock formations provide meager amounts of ground water because of their impermeable nature. However, despite low yields, these formations are an important source of domestic water supplies in this region. Recharge is limited in upland areas, and vertical permeability is greatly restricted.
Another source of ground water in the Scioto and Ohio River valley areas in southern Ohio is lenses (or pockets) of sand and gravel, which were deposited by glacial processes. These sand and gravel deposits usually are interbedded with mixtures of clay and silt. These aquifers are some of the most productive sources of ground water in Ohio.
The actual yield of a well, in gallons per minute (gpm), will vary considerably depending on the age and depth of the well, the diameter of the casing, well construction, pump capacity and age, and most importantly, properties of the geologic formation. The exact yield and depth of each well will depend on the properties of the geologic formation at the specific location of the well.
The Ohio Department of Natural Resources (ODNR), Division of Water, maintains a statewide database of more than 700,000 well logs. The Ground-Water Resources Section of the Division manages this valuable database, which includes some information collected by the U.S. Geological Survey (USGS) and the Ohio Environmental Protection Agency (Ohio EPA). Since 1948, well log information has been collected to increase the understanding of ground-water resources in Ohio. Geologists and hydrogeologists continue to study the state's ground-water resources, and as a result, Ohio is one of only a few states that has been completely mapped for ground-water availability (mapped by river basin, from 1959 to 1962).
Estimates of the size, shape, geologic make-up and yields of aquifers are being mapped county by county. Most of Ohio's counties have a completed map. The map presented in Figure 1 is a generalized representation of the water-bearing formations underlying Scioto County (adapted from map by Raab, 1989). This illustration is based on a hydrogeologic interpretation of the well log data from Scioto County and surrounding areas. It should be used only as a guide to understanding the ground-water resources in the county. The remainder of this section provides a brief description of the types of aquifers illustrated on the map in Figure 1.
Figure 1. Ground-water resources of Scioto County, Ohio
(modified from J.M. Raab, 1989, ODNR Division of Water,
by J.A. Humphreys).
An unconsolidated aquifer, indicated in Figure 1 as Area A, is comprised of coarse sand and gravel, deposited by glacier meltwater. Thin mixtures of clay and silt are also present in this aquifer, which lies near the Scioto River. Logs of wells drilled in this area indicate that as much as 100 feet of unconsolidated deposits fill this valley, and the principal water-yielding formation is as much as 35 feet thick. These large underground water supplies are freely recharged from the Scioto River by induced infiltration. Industrial wells, developed in permeable deposits of sand and gravel from 58 to 74 feet deep, have sustained yields of up to 1000 gpm.
The potential yield of wells in Area B ranges from 100 to 500 gpm. This aquifer is coarse-grained sand and gravel and is not recharged by the Scioto River. Test drilling is recommended in this area to locate the coarser, more permeable deposits of sand and gravel.
Wells drilled in these sand and gravel deposits have the potential to yield between 25 to 100 gpm. These sand and gravel deposits are located beyond the direct recharge influence of the Ohio River. Test drilling is recommended in this area to locate the coarser, more permeable deposits of sand and gravel.
In Area D, thick deposits of clay, silt and fine sand, occasionally interbedded with layers of sand and gravel, partially fill the ancient drainage channels. Thin, water-yielding sand and gravel layers or lenses may yield 5 to 25 gpm. Deeper drilling into non-water-bearing shale is not recommended because greater yields generally are not possible.
Deposits of silt and clay interbedded with thin lenses of sand and gravel partially fill the pre-glacial Teays drainage channel and major tributaries of the Scioto River. Wells usually range from 30 to 60 feet deep and yield 3 to 10 gpm. Yields do not usually exceed 10 gpm.
The shale and shaley sandstone aquifer illustrated as Area F is part of the predominant aquifer that underlies much of southeastern Ohio. The bedrock is overlain by thin clay and silt deposits. The potential yield from wells developed in these bedrock formations is less than 2 gpm. Brackish water is encountered at depths of 100 to 150 feet.
The water level in any well typically does not remain constant, but changes depending upon the proximity of adjacent wells and surface streams, and natural rainfall. Ground-water discharge and recharge greatly affect water levels in wells. The ODNR Division of Water monitors ground-water levels in wells throughout the state. However, none of these wells is located in Scioto County. One monitoring well is located in Pike County, near Piketon. This well is located in the same aquifer system as Area A in Figure 1. The observation well, designated as PI-2, is one of a number of wells throughout southern Ohio used to monitor the natural seasonal fluctuation, or the effects of nearby pumping, on water levels in sand and gravel, and bedrock aquifers.
Observation well PI-2 is 60 feet deep and completed in a sand and gravel aquifer within the Scioto River valley. This well is representative of many wells in the region finished in this type of aquifer. Continuous water level measurements have been recorded at PI-2 since September 1969. The lowest level recorded on PI-2 (near Piketon) was 27.5 feet below land surface in February 1977; the highest level recorded was 9.5 feet below land surface in June 1990.
Various state and federal agencies have participated in programs to determine the ground-water quality in Ohio. For four wells in Scioto County, water-quality data were available from the ODNR Division of Water. In Figure 1, these wells are noted as Chemical Analysis Sites 1 through 4. Sites 2 and 3 are test wells, and sites 1 and 4 are public-water supply wells.
The results from some of the chemical tests performed on these Scioto County wells are given in Table 1. The chemical constituents listed are total dissolved solids, hardness (as CaCO3), iron, chloride and sulfate. For comparison purposes, secondary drinking water-quality standards for these chemical constituents are also shown. These standards are established by the U.S. Environmental Protection Agency (USEPA) for public water systems for aesthetic reasons (taste, odor, appearance, etc.), and are not enforceable. These chemical constituents do not pose a risk to human health (see notes in Table 1). For private wells, there are no legally enforceable drinking water-quality standards other than total coliform, which is an indicator of bacteriological quality.
The
information in Table 1 can be used as a guide to what one might
expect from an existing or new well developed in similar geologic
material in the county. Even though all of these wells were developed
in the sand and gravel underlying Scioto County, and all are in the
range of 59 to 81 feet deep, some variation exists in the
concentrations of each of these chemical constituents. Just as well
yields differ, water quality will vary depending on aquifer
properties at the specific location of each well. One should not
forget that many human activities also affect the quality of ground
water.
Table 1. Chemical constituents of selected Scioto County wells. | |||||
---|---|---|---|---|---|
Well No. | 1 | 2 | 3 | 4 | WQ Std1 |
Well Depth (feet) | 59 | 60 | 81 | 70 | |
Capacity (gpm) | 600 | 900 | 450 | 12 | |
Depth to Bedrock (feet) | NE2 | NE | NE | NE | |
Water Bearing Formation3 | SG | SG | SG | SG | |
Chemical Constituents4 | |||||
Total Dissolved Solids | 456 | 413 | 152 | 216 | 500 |
Hardness (as CaCO3) | -5 | 380 | 130 | - | None6 |
Iron | 1.8 | 2.6 | 0.04 | 0.3 | 0.3 |
Chloride | 24 | 12 | 2.9 | 10 | 250 |
Sulfate | 96 | 61 | 24 | 60 | 250 |
1 USEPA Secondary Water Quality Standard. | |||||
2 Well constructed in this formation did not encounter bedrock. | |||||
3 SG - Sand and Gravel. | |||||
4 Units are parts-per-million, ppm;
Comments as per "Interpreting Your Water Test Report" (1988); Total Dissolved Solids: Concentrations above 500 ppm may cause adverse taste and deteriorate domestic plumbing and appliances. Use of water containing 500 ppm is common. Hardness: Primary concerns are that more soap is required for effective cleaning, a film may form on fixtures, fabrics may yellow, and scales may form in boilers, water heaters and cooking utensils. Iron: Concentrations greater than 0.3 ppm may cause rust-colored stains on laundry, plumbing fixtures and sinks. Metallic taste may be present which may affect the taste of beverages made from the water. Chloride: High concentrations may result in an objectionable, salty taste to water and the corrosion of plumbing in the hot water system. Sulfate: Concentrations in excess of 250 ppm may have laxative effect on persons unaccustomed to the water. Also affects the taste of water and will form a hard scale in boilers and heat exchangers. | |||||
5 Data not available. | |||||
6 No USEPA Secondary Standard. |
Scioto County's ground-water resources are valuable assets to the county's citizens and industry. The availability and quality of these resources are directly influenced by the properties of the geologic formations underlying the county. By understanding the physical and chemical nature of these resources, better decisions can be made about ground-water protection, management and use. This publication provided an overview of the county's ground-water resources. It should be used as a guide, and not as a substitute for detailed information and professional advice when drilling a well.
The Scioto County office of Ohio State University Extension can provide other publications on the county's water resources. Your Extension agent, the Scioto County Department of Health, and Ohio EPA Division of Drinking and Ground Water (1800 WaterMark Drive, Columbus, OH 43266) can provide information on well-water testing and drinking-water quality. The ODNR Division of Water - Ground-Water Resources Section (Fountain Square, Columbus, OH 43224) is an excellent source of information on ground water. Some of the information in this publication was summarized from the map, "Ground-Water Resources of Scioto County," and other information available through the Division of Water. This map is much more detailed than that given in Figure 1, and the Ground-Water Resources Section can provide detailed information on ground-water availability and wells. The USGS, Ohio District (975 W. Third Ave. Columbus, OH 43212), also provides information concerning ground water in Ohio.
<Ground-Water Resources of Scioto County. 1989. J.M. Raab. ODNR Division of Water. (map).
Interpreting Your Water Test Report. 1988. D. Lundstrom and S. Fundingsland. AE-937, No. 13-AENG-10. North Dakota State University Extension Service.
Nonpoint Source Pollution: Water Primer. 1993. R. Leeds and L.C. Brown. AEX-465. Ohio State University Extension.
Ohio Ground-Water Quality. USGS National Water Summary - Ohio. 1986. U.S. Geological Survey Water-Supply Paper 2325.
Ohio Ground-Water Resources. USGS National Water Summary - Ohio. 1984. U.S. Geological Survey Water-Supply Paper 2275.
Scioto County Water Resources. 1993. J.C. Fisher, K.M. Boone and L.C. Brown. AEX-480.73. Ohio State University Extension.
Surface and Ground Water Terminology. 1990. L.C. Brown and L.P. Black. AEX-460. Ohio State University Extension.
Underground Water Resources (maps of various river basins). 1958-1962. ODNR Division of Water.
Water Testing. 1988. K. Mancl. AEX-314. Ohio State University Extension.
This publication was produced through the Ohio Water Resources Education Project, in cooperation with: ODNR Division of Water; Ohio EPA; USGS, Ohio District; and Ohio Department of Health (ODH). Project leaders are Larry C. Brown and Kristina M. Boone. Support for this publication was provided, in part, by: cooperating agencies; Ohio State University Extension, Scioto County; USDA Water Quality Initiative Funds; Overholt Drainage Education and Research Program; and USDA Extension Service Grant No. 90-EWQI-1-9018. The project leaders acknowledge the following reviewers: David Cashell (ODNR Division of Water); Scott Golden (Environmental Health, ODH); Steve Hindall (USGS, Ohio District); and Michael Preston (Ohio EPA Division of Drinking and Ground Water).
A special thanks to Michelle Roby, John A. Humphreys, and Ross A. Roberts (Agricultural Engineering Undergraduate Assistants) for help in manuscript preparation, and Judy Kauffeld, Publications Editor (Section of Communications and Technology, Ohio State University), for editorial and graphic production.
All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.
Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.
TDD No. 800-589-8292 (Ohio only) or 614-292-1868