For related articles and more information, please visit OCA’s CAFO’s vs. Free Range page, Minnesota News, Iowa News, and our Illinois  News page.

In a recent piece, I fretted about one problem with our reliance on industrially produced fertilizers: They come from scarce and non-renewable sources, meaning we’ll eventually run out of them. But there’s another, much more immediate downside to the synthetic nitrogen and mined phosphorus that drives industrial agriculture: They tend to leach out of soil and foul up water: both for drinking and recreation.

Environmental Working Group has just released an excellent report (available here) ON the impact of that pollution on water quality in Iowa, ground zero of US industrial agriculture. The condition of that state’s water is, in short dismal. EWG looked at data kept by Iowa’s Department of Natural Resources on 72 free-flowing streams across the state, comparing the 1999-2002 period and the 2008-2011 period. In the chart, right, note that the majority of streams are rated either “poor” or “very poor”-and that the situation has improved little if at all over time. The main culprits are nitrogen and phosphorus. Here’s EWG:

 The two pollutants most responsible for poor water quality ratings in the Index are nitrogen and phosphorus. In 55 percent of the monthly samples across all sites, nitrogen was the single worst pollutant, followed by phosphorus in 30 percent. Together, high levels of nitrogen and phosphorus set off a cascade of pollution problems that contaminate drinking water and damage the health of Iowa’s streams and rivers.

The health consequences are dire. Even at low levels, nitrates can cause reproductive and thyroid problems; while phosphorus, along with nitrogen, feeds toxic blue green algae blooms in lakes.

Now, Big Ag would like you to believe that much of the nutrient load in streams comes from municipal sewage and industrial runoff. That’s absurd. Citing Iowa DNR numbers, EWG debunks that claim. reporting that just 8 percent of the nitrogen and 20 percent of the phosphorus polluting Iowa’s streams comes from those sources. The rest comes from “non-point sources”-mostly agriculture. And whereas runoff from sewage and industrial operations is heavily regulated by the state of Iowa, EWG points out, water pollution from crop production isn’t.