Ohio State University Extension

Food, Agricultural and Biological Engineering

590 Woody Hayes Dr., Columbus, Ohio 43210

Wood County Ground-Water Resources

AEX-490.87

Dan Frobose
A. Wayne Jones
Larry C. Brown
Kristina M. Boone

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. This publication contains information about the ground-water resources underlying Wood County. Its purpose is to help the reader better understand the factors which influence the quantity and quality of ground water. An overview of the county's water resources is provided in the publication Wood County Water Resources, AEX-480.87.

Much of the water resource and water quality terminology used in this publication is described in Extension Facts Sheets AEX 460 and 465. Ohio Extension publications are available through the Wood 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.

Carbonate aquifers that underlie Wood County are composed of layers of limestone and dolomite. Limestone consists of fossilized sea shells, shell fragments, calcareous sand and consolidated limy 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, which underlie most of the western portion of Ohio, were deposited between about 400 and 500 million years ago. In most areas of this region, this bedrock is covered by a layer of glacial till, which is an unsorted mixture of clay, silt, sand, gravel and boulders deposited by glacial processes.

Limestone formations usually are adequate sources of 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 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. Ground water also occurs in lenses of sand and gravel deposited by glacial processes. These deposits occur above the carbonate bedrock and may be embedded in the glacial till or deposited in layers.

Well Yield

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.

Ground-Water Availability

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 Wood County (adapted from map by M. Hallfrisch, 1986). This illustration is based on a hydrogeologic interpretation of the well-log data from Wood 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 Wood County, Ohio (adapted from ODNR Division of Water map by J. Humphreys).

AREA A: Limestone and Dolomite Beneath Thin Glacial Till

The carbonate bedrock illustrated as Area A is the primary aquifer in the central and eastern part of the county. This aquifer consists of 25 to 100 feet of a mixture of clay, silt, sand and gravel, underlain by the limestone and dolomite bedrock. Most of the bedrock wells in the area are drilled for farms or private dwellings at depths of 50 to 150 feet and commonly yield from 15 to 40 gpm. Because of the variation in the fracture pattern of this bedrock formation, extensive test drilling is often necessary in order to locate and develop suitable high-yielding potential wells for towns or industries. Yields of 100 to 500 gpm have been recorded from limestone wells in the basin at depths of up to 400 feet. Figure 2 is a cross section of Wood County (referenced in Figure 1 as the line X-X') illustrating the thickness of glacially deposited material above the carbonate bedrock in the Maumee River and Tontogany Creek regions of Area A.

Figure 2. Generalized cross section of Wood County, Ohio (adapted from Underground Water Resources map, A-11, ODNR Division of Water, by R. Roberts).

AREA B: Limestone and Dolomite Underlying Clay

The limestone aquifer illustrated by Area B is very similar to that in Area A. The primary difference is that this area has more variation in the thickness of the glacial till above the bedrock. Yields as great as 150 gpm are obtained from wells drilled as deep as 200 feet into the limestone and dolomite bedrock. Larger supplies have been obtained from the same formations north of the basin in the vicinity of Toledo. Exploratory drilling in this area in Wood County may prove that similar quantities are available here. Wells drilled into limestone and dolomite are supplied through joints and solution openings in the rock. The number and size of these openings vary from one locality to another within the same rock formation. It is seldom possible to determine the presence of such openings from the surface.

Ground water, whether obtained from bedrock or glacial deposits, may require some treatment. In some areas, water containing concentrations of calcium carbonate (CaCO₃, i.e., hard water) and iron (greater than 0.3 ppm) may require treatment for some uses (see notes in Table 1). Wells drilled into shale or limestone may produce water that contains objectionable quantities of hydrogen sulfide (rotten egg odor). In general, the probability of obtaining sulfur in objectionable amounts increases with the depth drilled.

Ground-Water Levels

The water level in any well usually does not remain constant, but may change depending upon several factors. Rainfall distribution and amount, and fluctuating water level in a stream that is hydraulically connected to an aquifer, may affect ground-water recharge and discharge, and subsequently may affect the water level in area wells. Also, 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 monitors ground-water levels in many wells throughout northwestern Ohio. Currently, no observation wells are operational in Wood County, but observation wells are located in neighboring Hancock, Henry, Lucas, Ottawa, Putnam, Sandusky and Seneca counties. Some of these wells are located in formations that are similar to those in Wood County, and may provide general information about aquifers in the area.

Ground-Water Quality

Various state and federal agencies have participated in programs to determine the ground-water quality in Ohio. For nine wells in Wood 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 9. These sites are either municipal or domestic wells.

The results from some of the chemical tests performed on these Wood County wells are given in Table 1. The chemical constituents listed are total dissolved solids, hardness (as CaCO₃), iron, manganese, chloride, sulfate 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. Except for fluoride concentrations greater than 4.0 ppm, 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. This information provides a general representation of the quality of the water at the time of sampling, which was not the same for all wells. In most cases, the data provided in Table 1 was taken from a water sample obtained just after the well was put into operation. Even though all nine of these wells were developed in the limestone underlying Wood County, and all are in the range of 60 to 500 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 the properties of the geologic formation 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).

Table 1. Chemical constituents of selected Wood County wells1.
Well No.	1	2	3	4	5	6	7	8	9	WQ Std2
Well Depth (feet)	305	250	235	260	230	250	500	60	201
Capacity (gpm)	100	100	25	460	25	10	125	30	300
Depth to Bedrock (feet)	43	48	22	28	20	1	65	58	34
Water-Bearing Formation3	LS	LS	LS	LS	LS	LS	LS	LS,G	LS
Chemical Constituents4
Total Dissolved Solids	600	368	2240	392	1460	874	2850	2772	1400	500
Hardness (as CaCO3)	437	262	1760	362	958	581	2120	1800	984	none5
Iron	-6	1.3	3.1	0.36	1.6	0.03	0.32	1.50	-	0.3
Manganese	0.01	0.03	0.05	0.02	0.5	-	0.08	0.04	-	0.3
Chloride	37	12	18	9	63	222	48	46	25	250
Sulfate	260	136	1410	50	888	110	1910	1720	840	250
Fluoride	1.97	1.0	1.6	0.7	2.1	0.66	1.7	1.4	1	2
1 Data on these wells from map by Hallfrisch (1986); General location of each well is located on Figure 1.
2 USEPA Secondary Water Quality Standard.
3 G - Gravel; 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. Iron and Manganese: Iron concentrations greater than 0.3 ppm and manganese concentrations greater than 0.03 may cause brown or black stains on laundry, plumbing fixtures and sinks. Metallic taste may be present, which may affect the taste of beverages made from the water. Chloride: Concentrations greater than 250 ppm 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 people unaccustomed to the water. Also affects the taste of water and will form a hard scale in boilers and heat exchangers. 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.
6 Data not available.

Summary

Wood 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. The limestone formations underlying Wood County have excellent potential to supply water adequate for domestic and agricultural uses, and most municipal uses. 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.

Where to Get More Information

The Wood County office of Ohio State University Extension can provide other publications on the county's water resources. Your Extension agent, the Wood County Health Department, and Ohio EPA Northwest District Office - NWDO (347 North Dunbridge Rd., Bowling Green, OH 43402) 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 a map titled Ground-Water Resources of Wood 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 about ground-water availability and wells. The USGS, Ohio District (975 W. Third Ave. Columbus, OH 43212), also provides information concerning ground water in Ohio.

Bibliography

Geohydrology and Quality of Water in Aquifers in Lucas, Sandusky and Wood Counties, Northwestern Ohio. 1991. U.S. Geological Survey, Water-Resources Investigative Report 91-4024.

Ground-Water Resources of Wood County. 1993. M.P. Hallfrisch. ODNR Division of Water. (map).

Hydrogeology and Water Quality near a Solid- and Hazardous-Waste Landfill, Northwood, Ohio. 1989. U.S. Geological Survey, Water-Resources Investigative Report 88-4093.

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.

Northwest Ohio Water Plan. 1967. ODNR Division of Water.

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 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.

Wood County Water Resources. 1993. D.L. Frobose, K.M. Boone and L.C. Brown. AEX-480.87. 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 Kristina M. Boone. Support for this publication was provided, in part, by: cooperating agencies; Ohio State University Extension, Wood County; Wood County Commissioners; Overholt Drainage Education and Research Program; and USDA Extension Service Grant No. 90-EWQI-1-9018. The project leaders acknowledge the following reviewers: Larry Sorrells and Kathleen McLaughlin (Wood County Health Department); Lori Shank (USDA-Soil Conservation Service); Scott Golden (Environmental Health, ODH); Steve Hindall (USGS, Ohio District); and Tim Fishbaugh (Ohio EPA, NWDO).

A special thanks to Michelle Roby, Ross Roberts, and John Humphreys (Agricultural Engineering Undergraduate Assistants) for help in graphic and manuscript preparation, and Judy Kauffeld, Publications Editor (Section of Communications and Technology, Ohio State University), for editorial and graphic production.