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How Important Is Water Quality to Livestock?

Updated November 18, 2021
Professional headshot of Robin Salverson

Robin Salverson

SDSU Extension Cow/Calf Field Specialist

A stock pond with algae blooms developing throughout.

Water is the most important nutrient to all livestock animals and is sometimes overlooked. Poor quality water can have a negative effect on growth, reproduction, and general productivity of the animal. In some cases, death could occur within days or hours after consumption of contaminated waters or water deprivation. Therefore, continuous monitoring of water quality and quantity are important to maintain a productive livestock program.

What Are Some Factors That Affect Water Quality?


Salinity refers to the dissolved salts that are found in all water sources. However, salinity can be raised to a concentration that is toxic to livestock. Animals may refuse to drink for several days followed by consumption of large amounts of water or the animal drinks an adequate amount of water but dehydrates as a result of reverse osmosis. In either case, illness or death will result. Animals that have an increased requirement for water (i.e. lactation, pregnancy) will be the most susceptible to the salinity problem. High saline has been detected as a problem in South Dakota in past years. Limited snow run-off and dry conditions along with evaporation are all responsible for increased salinity concentration and should be a warning to producers that possible water problems may exist under these conditions. It is important to understand that limited run-off and drought, increases the risk of poor-quality water; however, there are water sources that are “bad” regardless of environmental conditions. Therefore, monitoring water quality and livestock during good times is just important as during poor years.


Alkali is a common sight in Western South Dakota. Excessive alkali can cause physiological and digestive problems in livestock. However, there are few instances where alkali is too high for livestock consumption.


High levels of nitrates can be detected in water, but more common sources of elevated nitrates are in forages (i.e. sorghum, sudan grass, oats). Nitrates themselves are not toxic, but the conversion of nitrates to nitrites in the rumen are responsible for conversion of hemoglobin into methemoglobin causing red blood incapable of carrying oxygen resulting in suffocation. Dark brown blood is a good indicator that nitrate poisoning was the culprit.

Blue-Green Algae

Blue-green algae has been a known killer among livestock in South Dakota. Ingestion of toxic alga bloom can kill an animal within 24 hours or less. The algae bloom can come and go very quickly as a result of increased moisture and cooler temperature so detection can be difficult. However, producers should be on the watch for bluish-green algae with the possibility of being dark green to brown in color during hot sunny days on surfaces of waters that are stagnant.

Monitoring and Testing Water Supplies

Salinity, alkalinity, nitrates, and blue-green algae are known factors that affect water quality in South Dakota, but contamination of waters sources are not limited to these factors. If you are questioning the quality of your water sources, monitor your water supplies and livestock. Which water supply are the animals drinking from? Are there hoof prints around the water source? Are there other organisms (i.e. fish, ducks, bugs) living in or around the water? What type of condition are your livestock in? What are the climatic conditions? Careful observation may help you solve or limit the possible problems. It is recommended to test your water sources when quality is in doubt.

SDSU Extension offers an on-site quick test at all SDSU Extension Regional Centers and some SDSU Extension County Offices across South Dakota.