DEALING WITH NITRATES IN DRINKING WATER SOURCES

In the United States, strict limits have been adopted on the permissible level of nitrates in finished water provided by public water supplies. These limits were developed particularly out of concern for infants who may be vulnerable to higher nitrate levels in drinking water.

Nitrates in ground water and surface water tend to be associated with agricultural areas where chemical fertilizers and animal manure appear to be the primary cause.

In March, 2012 the University of California at Davis released a study which allegedly found that nitrate contamination of ground water is pervasive in certain agricultural communities, where some wells have exceeded the standard. According to the study, nitrate leaching from agricultural land has caused 96% of current ground water contamination.

Nitrate impacts on surface waters such as rivers can occur from storm water farm run-off and from farm drain tiles, particularly in significant Spring rain events.

To deal with elevated nitrate levels in source waters, utilities may face complex challenges and resulting costs...costs that will have to be recovered from their customers. Installing effective treatment facilities particularly may be expensive for smaller water systems. Seeking alternative ground water supplies may not be feasible if nitrates have spread in an aquifer.

One midwest water utility which uses river water as its source of supply found that nitrate levels in the river exceeded the standard primarily only during Spring rain periods. So, it acquired an nearby empty gravel quarry to store river water during low nitrate periods, which then is blended with higher nitrate Spring river water to achieve compliance with the standard.

The same midwest utility also became proactive to work with the farm community to educate as to the impacts of over-fertilization of crop land. Through such an organizing effort, farmers began to understand not only such impacts but also the potential savings from reducing the types or quantities of fertilizer applications.

Along the same lines, a California trade group representing fertilizer manufacturers and retailers has stated that the California Department of Food and Agriculture has developed "best management practices" to mitigate nitrate contribution from fertilizer by optimizing fertilizer usage, matching nutrient supply with crop requirements to minimize nutrient losses. Such practices now may include split application of fertilizer based soil and plant testing and use of sensors for more precise nitrogen management.

So, it appears that parties concerned with both potential causes and effects of nitrate levels in drinking water sources are trying to deal with the issue.