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Lagoon Management for the Rainy Seasons
Lagoon Liquid Level Management
Author: James C. Barker, Emeritus Faculty, Biological and Agricultural, North Carolina State University
Proper lagoon liquid level management should be a year-round priority. Its importance is especially magnified during extended rainy and wet periods.
Lagoons consist of permanent storage volumes which provide bacterial treatment of the manure and storage for sludge accumulations. Liquids are not normally removed from these lower parts of the lagoon.
The top part of the lagoon, usually the upper 3-4 feet, is for temporary storage of the accumulated wastewater until it can be irrigated onto crops, grasses, or trees during periods when runoff is unlikely to occur. The National Resources Conservation Service can determine the depth in the lagoon where the permanent storage stops and the temporary storage begins. This depth should be marked by driving a stake in the bank. When the water level gets down to this depth, stop irrigating.
Maximum storage capacity should be available in the lagoon for periods when the receiving crop is dormant such as the wintertime or when we have extended rainy spells such as the thunderstorm season in the summertime. This means that at the first signs of plant growth in late winter / early spring, irrigation according to a farm nutrient management plan should be done on every occasion that the land is dry enough to receive the lagoon liquid, to make lagoon storage available for the thunderstorms. Similarly, in late summer / early fall, the lagoon should have been pumped down to the marker to allow for storage during the winter. Having a cool season grass, small grain or cover crop will also allow some winter irrigation.
Waiting until the lagoon has reached its maximum storage capacity before starting to irrigate does not leave any room for storing excess liquids during an extended wet period and negates the reason forhaving temporary storage in the lagoon in the first place. Overflow from the lagoon during this period foranything less than the 25-year, 24-hour storm would be in violation of water quality regulations and subject to penalty action.
Anerobic Lagoon Diagram
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