Figure 1. Ground-water resources of Clark County, Ohio (modified from J.J. Schmidt, ODNR Division of Water, by R.A. Roberts).
Michael E. Haubner
A.Wayne Jones
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 Clark 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 Clark County Water Resources, AEX-480.12, 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 types of geologic material from which the formation is composed influence 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 carbonate aquifer, which is composed of layers of limestone and dolomite, is a principal source of ground water in west central Ohio, which includes Clark County. Limestone consists of fossilized sea shells, shell fragments and consolidated limy mud. Its main mineral is calcium carbonate, CaCO3. Dolomite is similar to limestone, but has few recognizable fossils; its main mineral is calcium magnesium carbonate, (Ca,Mg)CO3. Limestone and dolomite are collectively referred to as carbonates. The limestone and dolomite formations, which underlie most of the western portion of Ohio, were deposited between about 400 to 500 million years ago. In most areas of this region, glacial till covers the bedrock. Till is an unsorted mixture of clay, sand, gravel and boulders deposited by glaciers.
Limestone formations are good sources of ground water because of their naturally formed solution channels, joints and fractures. The number of fractures and other openings in limestone varies greatly from one location to another and affects the amount of water that may be encountered when drilling a well. The position of such openings rarely can be determined from the land surface; therefore, there is always some uncertainty as to the production capability of a proposed well.
Another source of ground water in some areas in west central Ohio is lenses (or pockets) of sand and gravel that were deposited by glacial activity. These deposits may be embedded in the glacial till or deposited as glacial outwash.
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 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 data base of more than 700,000 well logs. The Ground-Water Resources Section of the Division manages this valuable data base, 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 the 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 Clark County (adapted from map by Schmidt, 1982). This illustration is based on a hydrogeologic interpretation of the well log data from Clark 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 Clark County, Ohio (modified
from J.J. Schmidt, ODNR Division of Water, by R.A. Roberts).
The Mad River buried valley aquifer illustrated in Figure 1 as Area A is one of the most productive aquifers in the state. The permeable sand and gravel deposits adjacent to Mad River can yield in excess of 1000 gpm to properly constructed wells. Average well depths are 80 to 120 feet.
Area B illustrates this high yielding carbonate aquifer, which is confined to the northeast corner of the county. Up to 430 feet of glacial drift overlies the limestone in this area. The limestone and dolomite can yield as much as 300 gpm at depths greater than 275 feet. Farm and domestic supplies of 5 to 15 gpm are developed from thick glacial drift at depths of as much as 225 feet.
The majority of the municipal and industrial wells in Clark County lie in the unconsolidated aquifers of sand and gravel illustrated as Area C. These are buried valley aquifers, but extend beyond the recharge influence of the Mad River. They contain extensive thick permeable deposits of sand, gravel, fine silts and clays. These deposits may yield up to 300 gpm, but extensive test drilling is recommended to locate coarse deposits at depths ranging from 35 to 155 feet.
Area D consists of sand and gravel deposits underlain by the regional carbonate aquifer. These deposits are variable in thickness and may yield up to 100 gpm to properly constructed wells. The carbonate bedrock below may yield up to 100 gpm at depths of less than 325 feet.
The shallow carbonate aquifer, illustrated as Area E, normally yields less than 15 gpm at depths of less than 100 feet. Deeper drilling to the underlying non-water-bearing shaley limestone is not recommended.
Fine-grained aquifers are illustrated as Area F. These aquifers resulted from valley fill of abandoned stream valleys. The permeability of these aquifers is often reduced by high clay and silt content. The underlying shaley limestone is non-water bearing. Thin layers of sand and gravel may be encountered at depths of less than 75 feet. Yields of 3 to 10 gpm may be developed.
Area G illustrates the ancestral Teays River Valley drainage channel that has been filled with glacial deposits. A generalized cross-section of the Teays Valley (referenced in Figure 1 as line X-X') is illustrated in Figure 2. This area contains the same type of deposits as does Area F. The "?" in Figure 2 indicates that sufficient data have not been collected to properly characterize these specific locations.
Figure 2. Generalized cross section of buried Teays drainage channel
in Clark County, Ohio (modified from Underground Water Resources map,
K-1, ODNR Division of Water)
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 effect water levels in wells. The ODNR Division of Water monitors ground-water levels in two wells in Clark County: one located north of Springfield is designated as CL-7 on Figure 1; the other located in New Carlisle is designated as CL-9. These are two of a number of wells throughout west central Ohio used to monitor the natural seasonal fluctuation, or the effects of nearby pumping, on the water levels in the buried valley aquifer.
Observation wells CL-7 (50 feet deep) and well CL-9 (113 feet deep) both are completed in sand and gravel. They are representative of many wells in the region. Continuous water-level measurements have been recorded at CL-7 since 1960 and at CL-9 since 1974. The lowest level recorded on CL-7 (Springfield) was 30.2 feet below land surface in February 1961; the highest level recorded was 8.2 feet below land surface in January 1991. The data from CL-9 (New Carlisle) indicate the lowest level recorded was 31.2 feet below land surface in July 1977; the highest level recorded was 18.2 feet below land surface in July 1980.
Various state and federal agencies have participated in programs to determine ground-water quality in Ohio. In Clark County, water-quality data for four wells were available from the ODNR Division of Water. In Figure 1, these wells are noted as Chemical Analysis Sites No. 1 and 2.
The results from some of the chemical tests performed on these Clark County wells are given in Table 1. The chemical constituents listed are total dissolved solids, hardness (as CaCO3), iron and sulfate. All concentrations are given in parts-per-million (ppm). For comparison purposes, 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). There are no drinking water-quality standards for private wells.
The information in Table 1 can be used as a guide to what one might expect from an existing or new well. Even though both of these wells were developed in formations underlying Clark County, and are in the range of 55 to 100 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 Clark County wells. | |||
|---|---|---|---|
| Well No. | 1 | 2 | WQ Std1 |
| Well Depth (feet) | 55 | 100 | |
| Capacity (gpm) | 100 | 2900 | |
| Depth to Bedrock (feet) | 55 | NE2 | |
| Water-Bearing Formation3 | LS | SG | |
| Chemical Constituents4 | |||
| Total Dissolved Solids | 372 | 452 | 500 |
| Hardness (as CaCO3) | 362 | 400 | None5 |
| Iron | 0.76 | 0.88 | 0.3 |
| Sulfate | 33 | 97 | 250 |
| 1. USEPA Secondary Water Quality Standard. | |||
| 2. Well constructed in this formation did not encounter bedrock. | |||
| 3. LS - Limestone; 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 may also 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 and may affect the taste of beverages made from the water. 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 No USEPA Secondary Standard. | |||
Clark 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 was designed to provide the reader with 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 Clark County Extension office can provide other publications on the county's water resources. Your Extension agent, the Clark County Department of Health and the 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 Clark County, and other information available through the Division of Water. This map is much more detailed than that given in Figure 1 of this publication. In addition, personnel in the Ground-Water Resources Section can provide you with more detailed information on ground-water availability and wells. The USGS, Ohio District (975 W. Third Ave., Columbus, OH 43212), also provides information about ground water in Ohio.
Clark County Water Resources. 1992. M.E. Haubner, K.M. Boone and L.C. Brown. AEX-480.12. Ohio Cooperative Extension Service, The Ohio State University.
Ground-Water Resources of Clark County. 1982. J.J. Schmidt. 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.
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.
Surface and Ground Water Terminology. 1990. L.C. Brown and L.P. Black. AEX-460. Ohio Cooperative Extension Service, The Ohio State University.
Underground Water Resources (maps of various river basins). 1958-1962. ODNR Division of Water.
Water Testing. 1988. K. Mancl., AEX-314. Ohio Cooperative Extension Service, The Ohio State University.
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; Clark County Extension office; Overholt Drainage Education and Research Program; USDA Extension Service Grant No. 90-EWQI-1-9018. The project leaders acknowledge the following reviewers: John H. Grieser (USDA-Soil Conservation Service); David Cashell (ODNR Division of Water); Scott Golden (Environmental Health, ODH); Randall Reeder (Agricultural Engineering, OSU); Steve Hindall (USGS, Ohio District); and Rich Bendula (Ohio EPA Division of Drinking and Ground Water).
A special thanks to Michelle Roby and Ross A. Roberts (Agricultural Engineering Undergraduate Assistants) for help in manuscript and graphics preparation, and Judy Kauffeld and Tonya Ewing (Section of Communications & Technology, OSU Extension), 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