Author of Response: Thomas Harter, Cooperative Extension Specialist, Groundwater Hydrology, University of California-Davis, thharter@ucdavis.edu
The most effective management practices for preventing pathogens from entering surface water is to prevent runoff of feces-contaminated water into surface water bodies. Where animals are produced on range or pasture, runoff cannot be contained. Field-based management includes using diversions to keep water from running onto a field treated with animal waste, utilizing no-till practices to minimize the amount of surface runoff that a field generates, and maintaining a sufficient buffer between a field edge and a flowing body of water. Timing of waste application can avoid the obvious problem of generating runoff just after waste application. As waste ages, the amount of pollution lost from it decreases. Applying waste just before a storm event is considered very poor management.
Utilizing a sound nutrient management plan will help to ensure that excess waste is not applied. Composting animal waste is not always a practical option, but where it is feasible, it will kill most pathogens in the waste, prior to land application. Surface water runoff prevention is particularly important in feedlots, corrals, exercise yards, and other forms of concentrated animal farming. It is important to control roof runoff onto feedlots, barnyards, milking parlors, etc. by piping the runoff safely away from whatever building generated the water in the first place. Keeping animals out of streams and lakes and maintenance of a vegetative buffer strip around streams, ponds, and lakes is of prime importance. The vegetative buffer strip provides a rough soil surface, forcing surface runoff to move into and out of the soil surface layer, and thereby providing ample opportunity for pathogens, especially larger pathogens such as Cryptosporidium and Giardia, to be removed prior to runoff entering a stream. There is no conclusive evidence that incorporation of manure during land application significantly affects the survivability and transportability of pathogens when compared to surface application. However, incorporation would minimize the potential for pathogen transport to surface water.
For groundwater protection, best management practices include proper well maintenance and the establishment of a protection zone around the well-head, particularly around shallow domestic wells. Good well maintenance includes construction and maintenance of a proper well seal and a sealed surface pedestal, installation of backflow prevention devices, and proper abandonment of inactive wells. This will prevent leakage of surface runoff into the well casing or into the annular space around the well pipe. Backflow prevention devices will keep water pumped into a reservoir (containing fertilizer, pesticides, or manure) from being sucked back into the well after the pump is shut off.
