Table 3-7: Agricultural/Rural Best Management Practices Groundwater Protection Assessments

(Back to Document)
1. Private Wells:  Contaminants of any kind should be prevented from entering the well directly. Contaminants should also be prevented from entering the soil in the vicinity of the well. The casing and well cap (seal) should be in good condition. There should be adequate backflow protection in the plumbing carrying water from the well. The water from the well should be periodically tested for contaminants, especially if it is a very old well or a well of questionable design.
2. Abandoned Wells: The well should be checked to see if it was properly abandoned according to the standards of the Oregon Water Resources Department. If it was not, and it is suspected of posing a threat to the groundwater, a judgement should be made as to whether or not additional steps can be taken to correct or improve the abandonment. In any case, contaminants should be prevented from entering the abandoned well directly or through the surrounding soil surface, particularly if the abandonment method is in question.
3. Pesticide Storage and Handling Areas: As the amount of pesticide stored or handled increases, the care with which it is managed should also increase. The more leachable pesticides should also be handled more carefully. If dry or liquid formulations are stored and handled, care should be taken that they not leak or spill onto the soil where they might leach to groundwater. The pesticides should be stored such that only properly trained workers have access to them. They should be stored downslope (or downgradient), and a sufficient distance away from, any wells. There should be adequate containment to prevent spills or leakage from reaching the soil and groundwater. Mixing and loading should be done in such a way as to prevent leaks, spills, or overflows onto the soil. Plans and equipment should be in place for containment or cleanup in case a spill does occur. The water source for mixing should have adequate backflow protection. Sprayer tanks and equipment cleaning rinsate should be properly disposed of (sometimes it can be applied to crops that might benefit from it). Used containers should be properly disposed of (SEE: "Pesticide Container Management Program" in the Resource List).
4. Fertilizer Storage and Handling Areas: Many of the general BMP's for pesticide storage and handling areas can also be applied to fertilizer storage and handling areas. The goal is simply to prevent large amounts of fertilizer from reaching the groundwater. Spills and leaking should be prevented if possible or at least minimized. Any fertilizer not being used by the plants is not only a potential threat to the groundwater, but also a waste of the farmer's money.
5. Livestock Waste Storage and Treatment: If large amounts of manure are being stored outside for an extended period of time, care should be taken to prevent leachate from reaching the groundwater. Large manure piles should be covered and/or on a non-permeable surface such that rainwater can't carry large amounts of leachate to the groundwater. If manure or liquid waste is stored in an unlined lagoon or pit it should be downslope and far enough away from any wells to prevent leachate from reaching the groundwater.
6. Petroleum Product Storage and Handling:

Fuel Tanks: The volumes of fuel added to, and dispensed from, underground tanks should be checked regularly to determine if leaks are occurring. Abandoned tanks should be properly removed or sealed to prevent leakage to groundwater of any residual fuel. Tanks, especially if underground, should be downslope and far enough away from any wells. Old tanks, without adequate corrosion protection, should be checked more frequently for possible leaks. Protection should exist to prevent overflows, spills and leaks from reaching the groundwater. Pumps, piping and hoses should be checked periodically for leaks. If serious questions remain about the integrity of an underground tank, groundwater and/or soil testing in the vicinity may be helpful. Overflows, spills and leaks of fuel can threaten the groundwater.

Lubricants/Hydraulic Fluids/Coolants: If large quantities of these materials are stored or handled the same precautions as for fuel may apply. Smaller amounts should be stored under cover to prevent rainwater from carrying contaminants to the soil or weather conditions from damaging containers. All materials should be labeled properly to prevent misuse. Overflows, spills and leaks should be prevented as much as is reasonably possible. Used materials should be recycled or disposed of properly.

7. Hazardous Waste Management:  Farm, vehicle/equipment maintenance, and home chemicals should be recycled or disposed of properly if not used up for their intended purpose. These chemicals should not leak, or be disposed of, onto soil in the vicinity of any wells. Empty containers for chemicals should be recycled or disposed of properly. Temporarily stored hazardous materials (solids or liquids) should be safely transported to a proper disposal facility in a timely fashion. The storage of hazardous materials near wells should be avoided. Used vehicle/equipment batteries should be recycled or disposed of properly.
8. Household Wastewater Management:  Chemicals which might harm the organisms in the septic tank, and thus make treatment less effective, should not be disposed of into the wastewater system. Drainfields should be downslope and away from any wells. Septic tanks need to be pumped out periodically (every 2 to 3 years) to maintain proper function.
9. Farm or Farm Household Waste Disposal/Fill Areas:  Materials which have the potential to readily leach through the soil and contaminate groundwater should not be disposed of onto the soil in the wellhead protection area. Animals should not be buried in the wellhead protection area if there is a significant chance that infectious organisms or nitrates from decaying corpses might contaminate the groundwater. Rendering companies may be willing to remove dead stock and the poultry industry is studying composting of dead birds. The risks of groundwater contamination may increase with the number or mass of animals buried. There should not be unmonitored public access to a disposal area that could lead to improper, or unknown, disposal.
10. Milking Center Wastewater Handling Facilities:  The storage or discharge of untreated milking center wastewater, such that it might contaminate groundwater, should be avoided. Discharge of wastewater should be downslope and away from any wells. If the wastewater is stored in unlined lagoons, or lined lagoons that might leak, there should be confidence that significant amounts are not leaching to the groundwater. These facilities must have permits. In Oregon, permit conditions require that adequate steps are taken to collect, store, and agronomically apply the wastewater.
11. Confined Animal Feeding Operations (CAFO):  CAFOs or feedlots should preferably be downslope and away from any wells. If a CAFO is unpaved, it should be determined if excess nutrients from manure pose a threat to groundwater. Runoff from paved CAFOs, if collected, should be diverted into treatment systems, and away from any wells. Where possible, excess solid wastes should be scraped off yards periodically to reduce nutrient concentration of runoff. Greater concentrations of livestock pose a higher threat to groundwater if wastes are not managed properly.
12. Livestock Grazing and Pastures:  Livestock watering facilities should be set up such that excess nutrients from manure are not readily leached to groundwater. If chemicals are applied to grazing areas for weed or pest control, management should take any threat to groundwater into consideration. The threat to groundwater may increase with increasing herd density.
13. Crop Production - Non-Irrigated and Irrigated:  Targeted control of "volunteer" crop plants (those that sprout in the field prior to planting season) eliminate these hosts of crop pests. Timely control of volunteer plants may reduce the need for pesticides later in the growing season. Application of pesticides and fertilizers should be matched to the actual need and uptake rates. Chemicals with a high leaching potential should be avoided on highly permeable soils. The location of different soil types in the fields should be known and soil tests should be done periodically to ensure proper application of chemicals and fertilizers. Animal waste and plant residue contributions to soil nutrient levels should be taken into account before application of fertilizer. Nitrification inhibitors and slow release nitrogen may protect the groundwater and provide more cost effective fertilization for the farmer's investment. Designated paths through fields for the tractors ("tramlines") can allow for more precise, and therefore efficient, application of fertilizers and chemicals. Any opportunity to apply fertilizers or chemicals more efficiently may reduce the threat to groundwater and save the farmer money in the long run. Sprayers, for example, should be well maintained and calibrated for this reason. Also, the rotation of chemicals used with different modes of action may reduce the total amount of chemicals used while still effectively controlling pests. Private, public and irrigation wellheads should be protected by vegetated "buffer zones" to reduce the chance of contamination.

Dry land, riparian, or wetland vegetation along borders of ag lands help slow surface runoff and trap excess nutrients, and can thus help to prevent their movement from fields to groundwater. Crop rotation and post-harvest cover crops can be helpful in reducing the amounts of pesticide and fertilizer needed. This is another general BMP that can save the farmer money while protecting the groundwater.

Chemical application rates or timing may be adjusted to better protect the groundwater. Information is available from the BMP guides and other resources listed in the Resource List. Organic farming is an alternative that some farmers have chosen over chemical application and if it exists in the wellhead protection area, chemical application would obviously not be a concern there (but nutrient/manure application still might be). Information on this and other ag practices are listed in the Resource List.

Fertilizer application would include applications of any soil nutrients or amendments which might pose a threat to groundwater and could exist on any farm. Some farmers have experienced savings in fertilizer costs, as a result of more frequent soil testing, and the subsequent application rate adjustment of manures and inorganic fertilizers, without a decrease in yield.

Irrigated crops may have the added factors of irrigation equipment, chemigation, fertigation and water management practices to consider. Water should ideally be applied when the plants need it and when it has the lowest tendency to evaporate or run off the soil surface. Application of water should be matched, as well as possible, to crop need and soil water holding capacity. Over watering should be avoided. Chemigation and fertigation systems should have backflow prevention and other safeguards against contaminating their water source. Local Extension agents and/or the Oregon Department of Agriculture should be consulted for the safety requirements for these systems if they exist in a wellhead protection area.

(Back to Document)

GW\WH5868BF