An increase in pollutants like nitrogen and phosphorus have resulted in declining water quality in southern Idaho’s Eastern Snake River Plain Aquifer (ESPA), according to a new report from the Idaho Conservation League (ICL).
While the aquifer supplies drinking water to 300,000 Idahoans, the ICL says that water is being contaminated by human activity, including the rapid growth of the state’s dairy industry. The report says an estimated 417,000 Magic Valley dairy cows produce the manure equivalent of 12 million people.
“That manure has to go somewhere,” said Josh Johnson, conservation associate in ICL’s Ketchum office. “Combine that animal waste with the fertilizer that’s used on the Snake River Plain and it’s too much for typical crops to absorb. The rest is free to drain into the aquifer or the river.”
Johnson said it is possible that groundwater recharge may be introducing polluted water to the aquifer. But he believes the root cause is more likely excess nitrogen and phosphorous from large industrialized dairy operations and irrigated agriculture.
The Conservation League’s report outlined four conclusions regarding aquifer water quality:
Nitrate contamination is a widespread and growing issue in the ESPA, with over two-thirds of sampled wells in the Magic Valley having measured concentrations above natural background levels, and in some areas, exceeding state/federal water quality standards. Limited phosphorus data indicates that this type of contamination is also growing and has the potential to exacerbate existing problems in the Snake River. Available data and modeling studies strongly indicate that nitrate and phosphorusconcentrations will continue to increase in the coming decades. These water quality issues will increasingly have more severe implications for Idaho’s ability to meet water quality standards and protect the health of residents in the Snake River Plain.
The ICL believes a combination of stricter state regulation of fertilizer and animal manure application and industry-wide implementation of best-management practices is necessary to begin addressing groundwater issues. Those practices include such things as cover crops, residue management, and no-till planting.
The Idaho Conservation League says the aquifer is emblematic of similar water quality issues across the state. In some areas, it claims, “it is now unsafe to swim or eat fish from the Snake River, due to a combination of over-allocation of the river’s water and pollution discharge from factories, municipalities, dairies, and farm fields.”
You can see the complete ICL report here.