Ohio State University Extension

Food, Agricultural and Biological Engineering

590 Woody Hayes Dr., Columbus, Ohio 43210

Allen County Ground-Water Resources

AEX-490.02-97

David A. Jones
James M. Raab
Larry C. Brown
Karen T. Ricker

Water stored under the earth's surface is a plentiful, yet precious, resource in most areas of Ohio. Many human activities may affect the quality and quantity of this resource. However, the availability and quality of this resource are influenced directly by the properties of the geologic formations that hold 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 and formations. This publication contains information about the ground-water resources underlying Allen County. Its purpose is to help the reader better understand the factors that influence the quantity and quality of ground water. An overview of the county's water resources is provided in the publication Water Resources of Allen County, AEX-480.02.

Much of the water-resource and water-quality terminology used in this publication is described in Extension Fact Sheets AEX 460 and 465. Ohio Extension publications are available through the Allen County office of Ohio State University Extension.

Aquifers

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, sand and gravel 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 aquifer underlying Allen County is the porous limestone and dolomite bedrock of the Bass Island and Lockport Groups. Limestone consists of fossilized sea shells, shell fragments, calcareous sand, and consolidated lime mud. The main mineral in limestone is calcium carbonate, CaCO₃. Dolomite is similar to limestone but has few recognizable fossils; its main mineral is calcium magnesium carbonate, (Ca,Mg)CO₃. Both limestone and dolomite are commonly referred to as carbonate rocks. The limestone and dolomite formations that underlie most of the western portion of Ohio were deposited about 400 to 500 million years ago. These formations are covered by a layer of glacial till, which is an unsorted mixture of clay, silt, sand, gravel, and boulders deposited by glacial processes.

Carbonate formations usually provide adequate sources of ground water because of their naturally formed solution channels, joints, and fractures which provide water storage capacity and pathways for water movement. The number of fractures and other openings in the carbonate rock 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 in limestone.

Ground water also occurs in lenses (or pockets) of sand and gravel deposited by glacial processes. In Allen County, these deposits occur interbedded within the glacial till, and in either of two buried valleys that cut through the county.

Well Yield

The 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.

Ground-Water Availability

To support the development of ground-water availability assessments in Ohio, the Ohio Department of Natural Resources (ODNR), Division of Water, maintains a statewide database of more than 700,000 well logs. The 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 the ground-water resources in Ohio (since the early 1950's, well drillers have been required by State law to file a construction log of each new well). Geologists and hydrogeologists continue to study the state's ground-water resources. As a result, Ohio is one of only a few states that has been completely mapped for ground-water availability (each county has a published, county-specific, ground-water map).

Estimates of the size, shape, geologic make-up, and yields of aquifers have been mapped for Allen County. The map presented in Figure 1 is a generalized representation of the water-bearing formations underlying Allen County (adapted from map by Kostelnick, 1981). This illustration is based on a hydrogeologic interpretation of the well-log data from Allen County and surrounding areas. It should be used only as a guide to understanding the ground-water resources in the county. The section below provides a brief description of the types of aquifers illustrated on the map in Figure 1.

Figure 1. Ground-water resources of Allen County, Ohio (adapted from Ground-Water Resources of Allen County map, R.J. Kostelnick, 1981, ODNR Division of Water; illustration prepared by Carlos Lopez).

AREA A: Limestone and Dolomite

Area A in Figure 1 is the primary and most productive aquifer in Allen County. Large-diameter wells drilled several hundred feet into this carbonate aquifer typically yield from 100 to 500 gpm. Farm and domestic wells usually obtain a sufficient supply at depths of less than 100 feet. Ground water from the carbonate bedrock sometimes contains hydrogen sulfide (H₂S), and wells drilled deep into the bedrock aquifer may also yield ground water high in sulfate (SO₄) and dissolved solids. These bedrock formations are covered with 10 to 70 feet of glacial till, which is an unsorted mixture of clay, sandy clay, and lenses of sand and gravel. In some areas, lenses of sand and gravel occur within the till layer in sufficient thickness to be used as a source of ground water for domestic and farm purposes.

AREA B: Sand and Gravel within the Ancestral Teays Valley

Located in two buried valleys, illustrated as Area B, are tributaries to the ancestral Teays River Valley. Commonly misunderstood to be an underground river, the Teays Valley is a remnant of an ancient drainage system that cut valleys into the carbonate bedrock before the area was glaciated. One of the valleys runs approximately north and south, nearly bisecting the county. The other valley turns north from the county line in Perry Township, then curves west to join the first buried valley in the vicinity of Fort Shawnee. Glacial advances filled both valleys with clay, silt, sand, and gravel, virtually erasing all surface evidence of their existence. At some locations, the glacial deposits may be over 300 feet thick. Isolated layers of sand and gravel are occasionally found deep within the buried valley deposits. The layers are usually capable of yielding 10 to 20 gpm to drilled wells. If permeable material is not encountered, wells should be drilled deeper into the underlying bedrock.

Figure 2 is a generalized cross section (referenced in Figure 1 as the line X-X'), which shows the range of depth to bedrock, as well as the variation in the composition of the glacial deposits within the buried valleys. The cross section illustrates the two buried valleys discussed above.

Figure 2. Generalized cross section of Allen County, Ohio (adapted from Ground-Water Resources of Allen County map, R.J. Kostelnick, 1981, ODNR Division of Water; illustration prepared by Kim Wintringham).

Ground-Water Levels

The water level in any well usually does not remain constant, but changes in response to several factors. Rainfall distribution and amount may affect ground-water recharge and discharge, and subsequently may affect the water level in area wells. Also, wells that are hydraulically connected to a stream may show fluctuations in the water-table level as the stream level changes. In some cases, depending upon the hydraulic properties of the geologic formation, the intense pumping of a well, or number of wells, may cause the water level in some nearby wells to be lowered.

The ODNR Division of Water, in cooperation with the USGS, manages a statewide network of water level observation wells. The network currently consists of 102 State-operated sites equipped with continuous water-level recorders. Water-level data are collected to provide a database for scientists and water resources managers to learn about short- and long-term water-level fluctuations.

While the ODNR Division of Water does not monitor ground-water levels in any wells in Allen County, it does monitor wells in neighboring Putnam and Hardin counties. These wells provide some indication of how ground-water levels may change in similar aquifer materials in Allen County. Observation Well PU-1, located in Putnam County (Columbus Grove, just north of the Allen County line), has been continuously monitored since July 1946. Observation Well HN-1, located in Hardin County (Alger, just east of the Allen County line), has been continuously monitored since April 1946. Well PU-1 is 110 feet deep, and has a land surface elevation of 770 feet above sea level. Well HN-1 is 40 feet deep and has a land surface elevation of 975 feet above sea level. Both wells are drilled into a limestone aquifer.

Continuous daily ground-water level measurements at Observation Well PU-1 shows a record low water-level measurement of 24.3 feet below the land surface in August 1962; and a high water-level measurement of 8.8 feet in December 1990. At Observation Well HN-1, a record low water-level measurement of 23.9 feet below land surface was recorded in August 1991; and a high water-level measurement of 5.8 feet recorded in July 1946.

Ground-Water Quality

Various state and federal agencies have participated in programs to determine ground-water quality in Ohio. For five wells in Allen County, water-quality data were available from the ODNR Division of Water. These wells are noted as Chemical Analysis Sites 1 through 5 in Figure 1. These sites are test wells.

The results from some of the chemical tests performed on these Allen County wells are given in Table 1. The chemical constituents listed are total dissolved solids, hardness (as CaCO₃), calcium, magnesium, chloride, sulfate, hydrogen sulfide, and fluoride. For comparison purposes, secondary drinking water-quality standards for these chemical constituents also are 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.

Table 1. Chemical constituents of selected Allen County, Ohio, wells.1
Well No.	1	2	3	4	5	WQ Std2
Well Depth (feet)	260	300	360	360	370
Capacity (gpm)	75	600	150	300	175
Depth to Bedrock (feet)	6	15	10	6	15
Water-Bearing Formation3	LS	LS	LS	LS	LS
Chemical Constituents4
Total Dissolved Solids	899	765	629	734	604	500
Hardness (as CaCO3)	661	587	478	590	463	none5
Calcium (Ca)	156	136	109	139	108	none
Magnesium (Mg)	66	60	50	59	47	none
Chloride	32	28	44	28	30	250
Sulfate (SO4)	404	295	197	256	197	250
Hydrogen Sulfide (H2S)	22	17	1.0	7.0	2.9	none
Fluoride	1.6	1.6	1.0	1.4	1.4	2
1. Data on these wells taken from map by R. J. Kostelnick, 1981; general location of each well is shown on Figure 1.
2. USEPA Secondary Water Quality Standard.
3. LS--Limestone.
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. Calcium and Magnesium: Important contributors to water hardness. When water is heated, these break down and precipitate out of solution, forming scale. Magnesium concentrations above 125 ppm may have a laxative effect on some people. 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. Hydrogen Sulfide: Gas that is readily water soluble. Considered highly undesirable in drinking water supplies because of its objectionable odor (rotten egg smell). Fluoride: At concentrations greater than 1.5 ppm, fluorosis (mottling) of teeth may occur. USEPA Primary Standard is 4 ppm.
5. No USEPA Secondary Standard.

The total dissolved solids in each of the five test wells are in excess of 500 ppm, above which adverse taste and deterioration of domestic plumbing and appliances are possible. It is recommended that waters containing more then 500 ppm of dissolved solids not be used if other less mineralized supplies are available. Total dissolved solids at levels between 600 and 900 ppm are found in Allen County. While the water is safe for human consumption, municipal and industrial users may find it less desirable. Many households throughout the midwest U.S. use drinking water supplies with concentrations of 2000 ppm and greater for human and agricultural uses.

Hardness is the property where the water forms an insoluble scum with soap, primarily because of the presence of calcium and magnesium. Water that is hard has no known adverse health effects, and may actually be more palatable than soft water. Hard water is primarily of concern because it requires more soap for effective cleaning, forms scum and crud, causes yellowing of fabrics, toughens vegetables cooked in the water and forms scale in boilers, water heaters, pipes, and on cooking utensils. The hardness of good quality water should not exceed 270 ppm measured as calcium carbonate. Unfortunately, water from Allen County wells has a measured hardness in the 460 to 660 ppm range making it less desirable for human and industrial uses.

Three of the five test wells indicated sulfate levels above 250 ppm, which can produce a laxative effect in persons unaccustomed to the water. These effects vary with the person and appear to last only until one becomes accustomed to using the water. Sulfate levels in excess of 250 ppm adversely affect the taste of water, and will result in scale formation on boilers and heat exchangers. Of concern is the intermittent occurrence of sulfate in well water. High sulfate content may make the water less desirable as a domestic or agricultural source. For these reasons the upper recommended limit for sulfate is 250 ppm. A small percentage of the wells in Allen County exceed this level.

The presence of sulfur may produce water that contains objectionable quantities of hydrogen sulfide gas (rotten egg odor). Hydrogen sulfide concentrations as small as 1 ppm can result in an offensive, rotten egg odor and taste. In general, the probability of obtaining sulfur in objectionable amounts increases with the depth of the well.

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. This information provides a general representation of the water quality at the time of sampling, which was not the same for all wells. In most cases, the data provided in Table 1 were taken from a water sample obtained just after the well was put into operation. Even though all 5 of these wells were developed in the limestone underlying Allen County, and these wells are in the range of 260 to 370 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 (see AEX 465).

Summary

The availability and quality of ground-water resources are directly influenced by the properties of the geologic formations underlying the county. While Allen County's productive carbonate formations have the potential to provide more than adequate quantities of water for domestic and agricultural uses, the quality of the water does present some limitations for municipal and industrial uses. By understanding the physical and chemical nature of the ground water in Allen County, better decisions can be made about ground-water protection, management, and use. This publication provides 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.

Where to Get More Information

The Allen County office of Ohio State University Extension can provide other publications on the county's water resources. Your Extension agent, the Allen County Health Department, and Ohio EPA (Northwest District Office, 347 North Dunbridge Rd., Bowling Green, OH 43402) can provide information on well-water testing and drinking-water quality. Your local health department and county Extension office also will be able to provide information about proper well construction and requirements for private water systems. For example, State law requires that each new well constructed must be cased to a minimum depth of 25 feet. The health department issues permits and inspects new well construction.

The ODNR Division of Water--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 Allen County, and other information available through the Division. This map is much more detailed than that given in Figure 1, and the Water Resources Section can provide detailed information on ground-water availability and wells. Currently the Water Resources Section is conducting a ground-water pollution potential study for the county. For information, contact the Division. In regard to constructing a new well, the Division maintains a list of the State's registered and bonded well drillers. Hydrogeologists in the Division may be able to provide you with a list of well drillers who are familiar with geological conditions in your area, and provide technical assistance on proper well construction.

An additional excellent source of Ohio ground-water information is the USGS, Ohio District (975 W. Third Ave., Columbus, OH 43212). The USGS has conducted and published a number of ground- and surface-water investigations in Ohio. Additional information on Ohio's geological formations can also be obtained through the USGS, and through ODNR's Division of Geological Survey.

Bibliography

Flood of June 13Ð15, 1981, in the Blanchard River Basin, northwestern Ohio. U.S. Geological Survey Water-Resources Investigations Report 82-4044.

Ground- and Surface-Water Terminology. 1994. L. C. Brown and L. P. Black. AEX 460. Ohio State University Extension.

Ground-Water Resources of Allen County. 1981. R. J. Kostelnick. 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. 1996. R. P. Leeds, L. C. Brown, and N. L. Watermeier. 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.

Underground Water Resources (maps of various river basins). 1958Ð1962. ODNR Division of Water.

Water Resources Data, Ohio, Water Year 1995. Volume 1. Ohio River Basin Excluding Project Data. 1996. U.S. Geological Survey Water-Data Report OH-95-1.

Water Resources Data, Ohio, Water Year 1995. Volume 1. St. Lawrence River Basin and Statewide Project Data. 1996. U.S. Geological Survey Water-Data Report OH-95-2.

Water Resources of Allen County. 1995. D. A. Jones, K. T. Ricker, and L. C. Brown. AEX-480.02. Ohio State University Extension.

Water Testing. 1988. K. Mancl. AEX 314. Ohio State University Extension.

Acknowledgments

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 Karen T. Ricker. Partial support for this publication was provided by these cooperating agencies and programs: Ohio State University Extension, Allen County; Allen County Farm Bureau; Allen Soil and Water Conservation District; Overholt Drainage Education and Research Program; and the Ohio Management Systems Evaluation Area project (USDA CSREES Grant No. 94-EWQI-1-9057).

The project leaders acknowledge the following reviewers: John Kellis (USDA-NRCS, Allen County); Bill Kelly (Allen County Health Department); Scott Golden (Environmental Health, ODH); Steve Hindall (USGS, Ohio District); Dave Cashell (ODNR Division of Water); and Tim Fishbaugh (Ohio EPA, NWDO). A special thanks to Carlos Lopez and Kate Weber (Undergraduate Engineering Assistants) for help in illustration preparation, and Kim Wintringham (Associate Editor, Section of Communications and Technology, Ohio State University Extension) for editorial and graphic production.