Ohio State University Extension Fact Sheet

Ohio State University Extension

Food, Agricultural and Biological Engineering

590 Woody Hayes Dr., Columbus, Ohio 43210

Avoiding Stream Pollution from Animal Manure


Karen Mancl
Michael A. Veenhuizen

Animal manure is well-recognized as a fertilizer and soil conditioner. Adding manure to the soil has agronomic benefits through the addition of plant nutrients (nitrogen, phosphorus and potash) and organic matter. These same nutrients that are beneficial in soil for plant growth are considered pollutants in water. The objective of any manure land application system must be to keep manure on the soil, where it has value, and out of water where it is a pollutant.

Pollutant Types

Ammonia is the most damaging water pollutant in manure. If conditions are right, the effects of ammonia in a stream can be recognized within a few minutes. Ammonia is very toxic to fish. Even very small amounts of ammonia released to a stream can cause a fish kill.

The toxicity of ammonia to fish depends on three factors: pH, water temperature and oxygen content. The higher the pH of the water, the smaller the amount of ammonia needed to kill fish. The higher the temperature of the water, the smaller the amount of ammonia needed to kill fish. Because of the temperature factor, ammonia discharged to a stream that may not kill fish in the winter could result in a fish kill in the summer. In addition, the lower the dissolved oxygen content of the water, the smaller the amount of ammonia needed to kill fish.

Organic matter discharged to a stream may kill fish. However, the effect is slower than with ammonia. As organic matter is "broken down" or decomposes, the oxygen in the water is used up. Therefore, less oxygen is available to support fish and other aquatic life.

The rate at which a stream can recover from a discharge of organic matter depends on its volume, flow rate, turbulence and water temperature. Large streams can accept more organic matter without adverse affects than can small streams because of dilution. Rapidly flowing, turbulent streams can recover faster from a discharge of organic matter because of re-aeration as the water moves downstream. The effect of adding organic matter to cold water is less than warm water because cold water can hold more oxygen. Also, decomposition of organic matter is slower at colder temperatures. The worst possible situation is to discharge organic matter into a small, slowly moving stream on a hot day.

Nutrients do impact the streams that receive them. The major damage or effect is most often noticed once the nutrients reach a stagnant portion of the stream, a lake or a pond. The plant nutrients nitrogen and phosphorus do a good job of growing plants both on land and in water. Lakes rich in nutrients are called eutrophic and are green with algae and aquatic plants.

Bacteria from livestock manure rarely causes health problems for people or animals, but the potential is there. Diseases are often transmitted in people and animals through the fecal/oral route. Disease-causing organisms may be present in the waste of an infected animal. If the organism is ingested by another animal, through food or water, the animal is exposed and risks being infected. Fortunately, disease-causing organisms do not thrive in the soil or water and are filtered out and die off. Therefore, it is important to maintain adequate separation distances between the potential pollutant and the water source. This provides an opportunity for disease-causing organisms to be filtered out and die off before reaching food and drinking water supplies.

Color is a pollutant not often considered. Water can be stained by animal manure, giving it a brown or reddish appearance. The color may not pose a water quality problem, but may alarm people using the water for recreation or water supply.

Preventative Measures

Avoiding stream pollution from manure is not difficult. Common sense is the rule to follow when handling manure. The principles of proper manure management and land application are presented in AEX 704, Land Application of Manure and Wastewater (part 1). These principles include:

  1. Maintain separation distances and buffer areas between land used for manure application and surface water drainage. With no slope a minimum buffer distance of 10 feet of vegetated ground or 25 feet of bare ground from streams and ditches is recommended (Figure 1). On frozen ground, 60 feet of vegetated ground or 150 feet of bare ground is recommended (Figure 2). Greater setbacks are recommended on sloping ground.

    Figure 1. Minimum buffer areas on non-sloping ground.

    Figure 2. Minimum buffer areas on non-sloping frozen ground.

  2. Restrict surface application of manure on sloping ground when it is frozen or just prior to rain.

  3. Take care when applying manure to fields with subsurface drainage, especially when the soil is dry and cracked. It is advisable to till the soil prior to application if cracks are present. All "blow holes" in the drainage system must be repaired prior to application. Surface inlets and french drains must be avoided.

  4. Limit one-time application volumes of liquid manure to the amount of moisture needed to bring the soil up to field capacity. Heavy applications can result in puddling and runoff.

  5. Limit application of manure nutrients to crop need. Excess application results in buildup of soil nutrients.

  6. Test manure and soil to determine appropriate application rates.

Ohio Regulations

The Ohio Water Quality Standards (Ohio Administrative Code 3745-1-04) specify that all surface waters of the state must be free from the following pollutants as a result of human activity: suspended solids, floating debris, color, odor, toxic substances and nutrients that create nuisance growths of aquatic weeds and algae.

The discharge of pollutants to the state's waters is regulated by the Ohio Environmental Protection Agency through the National Pollution Elimination permit system (NPDES). This applies to any controlled, direct discharges of animal waste to waters of the state regardless of operation size.

Dischargers of pollutants may be liable for civil penalties of up to $10,000 for each day of violation (Ohio Revised Code 6111.07). In addition, criminal penalties can be assessed up to $25,000 or up to one year of imprisonment or both (Ohio Revised Code 6111.99).

The Ohio Environmental Protection Agency also issues Permits to Install (PTI) on all livestock operations of more than 1,000 animal units. The Ohio Department of Natural Resources has pollution abatement responsibilities for livestock operations of less than 1,000 animal units. This program is administered through the Division of Soil and Water and the Soil and Water Conservation Districts.

The legislature has also directed the Ohio Department of Natural Resources Division of Wildlife to protect the wild animals of the state. Anyone found to be discharging pollutants to the state's water can be found in violation of the "Stream Litter Act" and fined up to $500 or sentenced to 60 days in jail, or both, for a first offense. If fish are killed as the result of a pollutant discharge, the party responsible is charged for all damages including the value of the wildlife killed, environmental damages and the costs of investigation. Current market prices are used to set the value of the animals.

In 1989, 16 fish kills in Ohio were caused by animal manure, resulting in the death of more than 20,000 fish and animals. Animal manure was also cited in 19 other pollution investigations that did not result in wild animal deaths. In 1989, agriculture led industry, transportation, municipal government and public service enterprises in the number of wild animals killed.

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 614-292-6181

| Ohioline | Search | Fact Sheets | Bulletins |