Agricultural Pollution Threatens Water Supplies in Central Iowa

Friday, August 5, 2016

On Thursday, Des Moines Water Works warned customers of elevated levels of microcystins, the toxins created by cyanobacteria, in their drinking water. These toxins cause acute problems with the liver, including liver failure, among other serious health problems. 

The utility was forced to switch water supplies and caution some residents to avoid consuming too much water.

Ironically, despite the presence of these toxins in drinking water, Water Works was not obligated to warn the public about the problem at all. The Environmental Protection Agency has set no legal limit for mycrosystin in water supplies, and federal law allows 10 days of elevated levels before utilities are required to inform consumers of any potential problems.

The utility accelerated the public warning due to increasing concerns about the effects of these agrotoxins on human health.

Des Moines regularly faces nutrient levels three times the allowable standard in its source water, and Water Works is currently involved in a lawsuit attempting to get the growers applying nutrients to take responsibility and clean up the mess.

But as pollution problems driven by industrial agriculture have received more attention, additional research has raised new concerns. 

Nitrogen has received the most attention to date, but phosphorous an often-overlooked hazard. Excessive quantities of both substances predominantly result from the application of fertilizer and manure to row crops – the nitrogen from synthetic fertilizers and the phosphorous from manure generated by animal feeding operations. Phosphorous feeds algae blooms and leads to the toxins in water.

But recent research demonstrated that when it comes to cyanobacteria and its toxic brethren, the two pollutants combine to amplify the problematic effects.

The levels and toxicity of microcystins are controlled by the amount of available nitrogen.  In an environment where excess phosphorous drives algae blooms and excess nitrogen is present, the nitrogen amplifies the toxic effects of the algae, making the byproducts more dangerous. 

In the past, visible algae blooms were the primary warning of microcystin problems. Now toxins being produced in Iowa rivers are fed by the two nutrients in highly excessive quantities, and visual blooms are no longer a solid indicator. 

The problem has become, in effect, invisible as smaller quantities of microcystin become more toxic when fertilized. Because the drinking water standards are so far behind the current science, Water Works has adopted new, more aggressive testing and outreach efforts. It notified the public when the problem was discovered, and enabled individuals act according to their own needs and concerns.  

Des Moines is fortunate because it has two major rivers from which to draw drinking water, and switching the source water allowed Water Works to dilute the toxins to safe levels. Most cities don’t have that option, and in coming weeks, those downstream from Des Moines will face the challenge of removing the agrotoxins or may forego using tap water altogether.

Cities and drinking water utilities shouldn’t face these problems alone. 

The EPA needs to update data on agrotoxin problems, lay out clear limits of what is acceptable in drinking water, and require warning procedures when problems arise. Also, the EPA and state governments continue to ignore the volumes of evidence that demonstrate that voluntary, subsidy-dependent, agricultural conservation programs with no goals, no timelines and no regulations are simply not working. 

Despite billions of dollars in annual subsidies, this year’s gulf hypoxia report noted that even with decades of investment in voluntary programs, “no progress has been made” in reducing nitrogen levels flowing down the Mississippi River

We must change our approach before Des Moines, and the rest of the Midwest, find its drinking water permanently polluted by agrotoxins.


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