Figure 1. Average monthly precipitation (in inches) in Darke County, Ohio (1961-1990); data collected at Greenville Water Plant.
James R. Sutherly
Karen T. Ricker
Larry C. Brown
Water is a resource often taken for granted. In recent years, water availability and quality have become important public concerns in Darke County. The county's population of 53,619 (1990 census data) is predominantly rural, and 75 percent of the households rely on ground water for their water supply. This fact sheet provides a brief overview of Darke County's water resources, and is intended to help increase public awareness and understanding about this vital resource. By understanding where water is obtained and how it is used in the county, residents can gain a better appreciation for their water supply. The 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. Ohio State University Extension publications are available through all Ohio county Extension offices.
An average of approximately 37 inches of precipitation falls on Darke County annually. Figure 1 illustrates the average monthly precipitation for the county for the period 1961 to 1990. Based on this 30-year record, the average precipitation is 3.1 inches per month, with January (1.9 inches) typically being the driest month, and July (4.3 inches) the wettest. However, there can be extreme variations in some years and in certain months within a year. Such seasonal and yearly extremes may have serious consequences, and are not always apparent from the long-term precipitation information.
Figure 1. Average monthly precipitation (in inches) in Darke County,
Ohio (1961-1990); data collected at Greenville Water Plant.
Eighty-five percent of Darke County lies within the Great Miami River Basin which ultimately empties into the Ohio River. Most of the county is drained by the Stillwater River, Greenville Creek and their tributaries. The northwest corner of the county is drained by the Wabash River and the Mississinawa River. A generalized surface-water map of Darke County is given in Figure 2.
Surface waters are affected by the soil type and topography of the land adjacent to them, and the way humans use the land. Land use, such as residential development, construction, and agricultural production, can increase the amount of sediment entering a body of water. The type of soils in an area also influences surface water because of the soil's infiltration and water holding characteristics. With some soils, rainfall is more likely to run off, while other soils allow water to infiltrate more readily.
The county contains approximately 383,800 land acres, of which 85 percent is farmland. Thirty-three soil types have been identified in the county and vary in drainage ability from well drained to poorly drained. A large portion of the soils are medium textured and formed by glacial till and loess, while some other soils are medium to coarse textured and formed by glacial outwash. The county water acreage consists of about 140 acres of lakes, including the 57-acre Wabash Reservoir. The remaining water acreage consists of smaller ponds that range in size from 5 to 17 acres, most of which are privately owned and maintained. The county contains approximately 250 linear miles of major streams and rivers [estimated from river basin maps, Ohio Department of Natural Resources (ODNR) Division of Water]. In addition, 225 miles of county maintained ditches and numerous miles of privately maintained ditches are used for land drainage. This availability lends itself to many uses by both communities and individuals.
Figure 2. Surface-water resources in Darke County, Ohio (adapted from
ODNR Division of Water river basin maps; illustration prepared by H.
Landfried).
Darke County's primary ground-water source is the carbonate aquifer composed of limestone and dolomite bedrock. Limestone is composed of calcium carbonate, while dolomite is composed of calcium and magnesium carbonates. Together they form a popular construction material that most Ohioans refer to as limestone.
The limestone and dolomite aquifer in the northern part of Darke County produces yields that exceed 100 gallons per minute (gpm). Farm and domestic supplies at rates of over 10 gpm can be achieved at depths of 128 feet or less in this region. The carbonate aquifer in the southern half of the county typically yields 25 to 100 gpm from wells 80 to 125 feet deep. Several buried valleys running northeast to southwest, that have been filled with interbedded layers of silt, clay, sand and gravel, also exist in the county. Yields from properly screened wells in this aquifer can exceed 500 gpm in areas near Greenville and Versailles.
Ground-water supplies in the county, whether they are developed from bedrock or glacial deposits, have a high natural mineral content resulting in hard water. This water usually is treated for domestic use. Varying amounts of iron are found, and objectionable amounts of hydrogen sulfide generally increase with the depth drilled. An overview of the ground-water resources in the county is given in Darke County Ground-Water Resources, AEX-490.19.
The yield of a well will vary considerably depending on the age and depth of the well, well construction, the diameter of the casing, pump capacity and age, and more importantly, properties of the geologic formation. Specific information on ground-water availability and wells can be obtained by contacting ODNR Division of Water.
Based on long-term weather records, Ohio receives an average of 38 inches of precipitation per year. These 38 inches move through a complex path called the hydrologic cycle. Of these 38 inches, about 10 inches (26 percent) become runoff, which moves immediately to surface-water bodies such as streams and lakes. Two inches are retained at the ground surface and evaporate back into the atmosphere in a relatively short period of time. Twenty-six of the 38 total inches enter the soil surface through infiltration. Twenty of these 26 inches go into soil storage and later are returned to the atmosphere by the combination of evaporation and transpiration (evapotranspiration). The remaining 6 inches of precipitation (16 percent of the total) have the potential to recharge the ground-water supply. Two of these 6 inches eventually move to springs, lakes, or streams as ground-water discharge. The remaining 4 inches either return to the atmosphere by evapotranspiration or are withdrawn to supply water needs. For further reading, refer to Ohio's Hydrologic Cycle, AEX 461.
Statewide averages applied to the county's average annual precipitation, provide a rough estimate of how many inches will result in runoff and how many inches have the potential to reach aquifers. Based on statewide averages of runoff and ground-water recharge, Darke County's 37 inches of average annual precipitation result in about 9.6 inches of runoff to streams and lakes, and approximately 5.9 inches have the potential to recharge aquifers annually. Values for particular locations will differ according to local conditions.
Water use for each of Darke County's public water-supply systems is given in Table 1. For each water system, this table presents an estimate of the population served, water source, estimated daily usage and treatment plant capacity. The county's largest public-water system is the City of Greenville, which uses Greenville Creek and Mud Creek, in conjunction with seven ground-water wells for its supply. All other water sources used by citizens of the various towns and villages come from ground-water sources in each respective locality.
Ground water is a major water source for rural households in Darke County. Approximately 53 percent of all households obtain their water from private wells. Based on an estimated usage of 75 gallons per person per day, 2,134,125 gallons per day (gpd) from private wells are used. Additional private water uses include industry (1,930,000 gpd) and livestock use (1,230,000 gpd), mostly from ground-water supplies. The remaining 47 percent of households use public-water supplies with ground water and surface water as the source, as identified in Table 1.
Some water users in Ohio must register their withdrawals with the ODNR Division of Water. Through the Water Withdrawal Facility Registration Program, owners of facilities capable of withdrawing 100,000 gpd (70 gpm) or more must register those facilities. Information collected through this program includes withdrawal capacity, ground- or surface-water sources, location and type of water use, and location of discharge points. The program is for registration only, and not for allocation or permission. Registered withdrawers file annual reports of their water use. This information helps planners at ODNR to determine the availability of water for projected needs, and to better manage and protect Ohio's water resources. Documenting water use also provides official records for individual uses. For more information, contact ODNR Division of Water.
| Table 1. Water Use in Darke County, Ohio.1 | ||||
|---|---|---|---|---|
| Public Water System | Population Served | Primary Water Source | Water Usage (GPD)2 | Treatment Plant Capacity (GPD) |
| Ansonia | 1,267 | Ground Water | 220,000 | 504,000 |
| Arcanum | 1,957 | Ground Water | 224,000 | 410,000 |
| Bradford | 2,006 | Ground Water | 216,000 | 430,000 |
| Gettysburg | 539 | Ground Water | 48,300 | 144,000 |
| Greenville | 13,200 | Ground&Surface | 1,983,000 | 6,000,000 |
| New Madison | 1,008 | Ground Water | 98,500 | 170,000 |
| Union City | 2,000 | Ground Water | 159,000 | 360,000 |
| Versailles | 2,400 | Ground Water | 266,000 | 720,000 |
| Other3 | 787 | Ground Water | 76,600 | N/A |
| 1 Estimates from Ohio EPA using adjusted 1993 data; information is based on available data at time of publication. | ||||
| 2 GPD = gallons per day. | ||||
| 3 Includes mobile homes parks, and Northtown Apartments; total treatment plant capacity figure not available. | ||||
Natural processes and human activities affect the quality of our water supplies. Throughout Ohio, human activities contribute to both point and nonpoint source pollution. Point source pollution is the introduction of impurities into a water supply source (ground water or surface water) from an identifiable, known location. Examples of point sources can include industrial plants, power plants, commercial businesses, and wastewater treatment facilities.
Nonpoint source pollution also involves the introduction of impurities into a surface-water body or an aquifer, except the route is usually non-direct and the sources are "diffuse" in nature. A major portion of the sediment, nutrients, acids and salts, heavy metals, toxic chemicals, and pathogens enter the state's water resources through nonpoint source pollution, affecting both ground and surface water. Examples include automobile emissions, runoff from parking lots, and runoff and drainage from agricultural fields, feedlots, home lawns and gardens, residential development, construction, mining, and logging activities.
As water moves through the fractured limestone and unconsolidated material underlying Darke County, it dissolves the minerals contained in these formations and carries them in solution. Publication AEX 490.19 summarizes some of the county's natural ground-water quality aspects.
Human activities, such as agricultural production, domestic waste disposal, and lawn and turf care, may have some influence on the county's ground-water quality. In a 1987 study by Heidelberg College, 101 wells in the county were sampled for nitrate-nitrogen content, of which 94 (93 percent of total) contained nitrate-nitrogen concentrations in the range of 0 to 0.3 parts-per-million (ppm). This range is assumed to represent natural background levels. Two wells (2 percent) tested in the 0.3 to 3.0 ppm range; these values may or may not indicate human influence. The 3 wells (3 percent) that tested in the range of 3.0 to 10 ppm, may indicate elevated concentrations resulting from human activities. Only 2 wells (2 percent) tested at over 10 ppm for nitrate-nitrogen, which exceeds the safe drinking-water standard. The average test value for the 101 wells sampled was 0.45 ppm.
In 1993 an additional study was conducted by the Darke County Extension Office in which 92 wells were sampled. The sampling, conducted by the Greenville Water Plant, evaluated nitrate-nitrogen concentrations, coliform bacteria, and pH levels. Of the 92 samples taken, 78 (84 percent of total) contained nitrate-nitrogen concentrations in the range of 0 to 0.3 ppm. Twelve of the 92 wells sampled (14 percent) were in a range of 3.1 to 10 ppm which could indicate that human activities influenced the elevated concentrations. Only 2 wells in this sample (two percent) contained nitrate-nitrogen concentrations of 10 ppm, which exceeds the safe drinking-water standard. Design, location, and condition of a well, combined with the characteristics of the soils and geologic formations in which the well is constructed, influence the potential for pollutants to enter the well. Bacterial counts are another indicator of ground-water quality. The Darke County Department of Health tests water samples for concerned citizens, and results of these tests generally indicate safe drinking water in the county.
Runoff and sediment from residential development, construction sites and agricultural lands may enter the county's streams and lakes. Also, runoff may carry other pollutants, such as lawn and agricultural chemicals (pesticides and fertilizers), effluent from septic systems, oil and gas from spills, and industrial wastes.
Through the Ohio Nonpoint Source Assessment and Water Resources Inventory, the Ohio Environmental Protection Agency (Ohio EPA) and ODNR have identified 13,000 stream miles in Ohio that have been affected by nonpoint source pollution. Darke County contains portions of several streams and their tributaries that have been classified by the Assessment as being affected by nonpoint source pollution. Based on the findings of the Assessment and Inventory, the Ohio Nonpoint Source Management Plan has been implemented to help improve the quality of the state's waters. For specific information about the streams and tributaries listed in the Assessment and details of the Management Plan for the county, contact the Ohio EPA Southwest District Office (40 S. Main St., Dayton, OH 45402).
Overall, Darke County has a safe supply of water. County citizens have a major challenge to protect water resources from pollutants that could affect the quality of the water supply. For more information about nonpoint source pollution, refer to Nonpoint Source Pollution: Water Primer, AEX 465, available from your county Extension office.
Water availability and quality are important public concerns. Water problems can be both costly and inconvenient. While the present and future availability of water is good for Darke County, water is a precious resource that must be conserved and protected. We must all work together to maintain an adequate supply of good quality water.
This fact sheet provides information about the water resources in Darke County. For more information concerning water resources or drinking-water quality in the county, contact the Darke County office of Ohio State University Extension (700 Wayne St., Greenville, OH 45331). In addition, the following agencies may be able to provide information on other water resources topics in the county: Darke Soil and Water Conservation District; Darke County Health Department; ODNR Division of Water (Fountain Square, Columbus, OH 43224); US Geological Survey (USGS), Ohio District (975 W. Third Ave., Columbus, OH 43212); Ohio EPA (1800 WaterMark Dr., Columbus, OH 43215-1099); and Ohio Department of Health (ODH; P.O. Box 118, Columbus, OH 43226).
Darke County Ground-Water Resources. 1994. J. R. Sutherly, J. M. Raab, L. C. Brown, and K. T. Ricker. AEX-490.19. Ohio State University Extension.
Darke County, Ohio Soil Survey. 1979. USDA-SCS.
Darke Soil and Water Conservation District Resources Inventory. 1986. USDA-SCS.
Doane's Agricultural Report. 1992. Farm Water Systems.
Estimated Water Use in Ohio, 1990, Public Supply Data. 1993. USGS Open-File Report 93-72.
Gazetteer of Ohio Streams. 1960. Ohio Water Inventory Report No. 12. ODNR Div. of Water.
Ground-Water Resources of Darke County. 1993. J. M. Raab. ODNR Div. of Water. (map).
Hydrologic Atlas for Ohio: Average Annual Precipitation, Temperature, Streamflow, and Water Loss for the 50-Year Period 1931-1980. 1991. L. J. Hartstine. Water Inventory Report No. 28. ODNR Div. of Water.
Inventory of Municipal Water-Supply Systems by County, Ohio. 1977. Ohio Water Inventory Report No. 24. ODNR Div. of Water.
Inventory of Ohio's Lakes. 1980. Ohio Water Inventory Report No. 26. ODNR Div. of Water.
Monthly Station Normals of Temperature, Precipitation, and Heating and Cooling Degree Days, 1961-90, Ohio. 1992. Climatology of the United States, No. 81 (by state). NOAA.
Nitrate and Pesticides in Private Wells of Ohio: A State Atlas. 1989. Water Quality Laboratory, Heidelberg College.
Nitrate In Drinking Water. 1987. K. M. Mancl. Bulletin No. 744. Ohio State University Extension.
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. USGS Water-Supply Paper 2325.
Ohio Ground-Water Resources. USGS National Water Summary-Ohio. 1984. USGS Water-Supply Paper 2275.
Ohio Nonpoint Source Management Program. 1993. ODNR.
Ohio Population by Governmental Unit. 1991. Ohio Data Users Center, Ohio Department of Development.
Ohio Surface-Water Resources. USGS National Water Summary-Ohio. 1985. USGS Water-Supply Paper 2300.
Ohio Water Firsts. 1985. S. L. Frost and W. S. Nichols. Water Resources Foundation of Ohio, Inc.
Ohio Water Resource Inventory: Executive Summary and Volumes 1-4. 1992. Ohio EPA.
Ohio's Hydrologic Cycle. 1990. L. C. Brown and K. M. Coltman. AEX 461. Ohio State University Extension.
Private Water Systems Handbook. 1987. MWPS-14. Midwest Plan Service, Ames, IA.
Southwest Ohio Water Plan. 1976. ODNR Div. of Water.
State of Ohio Nonpoint Source Assessment: Volumes 1-6. 1990. Ohio EPA.
Surface and Ground Water Terminology. 1990. L. C. Brown and L. P. Black. AEX 460. Ohio State University Extension.
Water-Ohio's Remarkable Resource. 1982. ODNR Div. of Water.
Withdrawal and Distribution of Water By Public Water Supplies in Ohio, 1985. 1989. USGS Open-File Report 89-423.
This publication was produced through the Ohio Water Resources Education Project, in cooperation with: ODNR Division of Water; Ohio EPA; USGS, Ohio District; and ODH. Project leaders are Larry C. Brown and Karen T. Ricker. Partial financial support for this publication was provided by these cooperating agencies: Darke County office of OSU Extension; Darke County Commissioners; Overholt Drainage Education and Research Program; and the Ohio Management Systems Evaluation Area Project (USDA Extension Service Grant No. 90-EWQI-1-9018). The project leaders express appreciation to the following reviewers: Dennis Baker (Darke County Office of OSU Extension); Jim Bennent (USDA Soil Conservation Service, Darke County); James M. Raab, David Cashell and Leonard Black (ODNR Division of Water); Scott Golden (Environmental Health, ODH); Steve Hindall (USGS, Ohio District); Robert Burris (USDA Soil Conservation Service, State Office, Columbus); Jay Fleming (Ohio EPA Division of Drinking and Ground Waters); and Larry Antosch (Ohio EPA Division of Surface Water).
A special thanks to Michelle Roby (Agricultural Engineering Undergraduate Assistant) for help in manuscript and illustration preparation, and Kim Wintringham, Associate Editor (Section of Communications and Technology, Ohio State University 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