Rural Communities Tackle the Problem of Nitrate Contamination

Jan 24, 2014  | 00:06:26  | Ep3922

In 2013, Iowa recorded its wettest April in 141 years.    Nitrogen not absorbed by crops the previous year, meandered its way into local waterways and streams as run off, and the two rivers that supply water to Des Moines, the state’s largest city, contained record levels of nitrates.  By law the Environmental Protection Agency requires that drinking water contains no more than 10 milligrams of nitrates per liter.  But the Raccoon River tested at 24 milligrams per liter last spring, while the Des Moines River contained 18.

And the person responsible for maintaining safe drinking water for half-a-million central Iowans points the finger directly at agriculture as the source of the problem.

Bill Stowe, Des Moines Water Works: “...there are urban contributors to runoff and pollution. I don’t mean to disparage that, but the idea that “feeding the world” is somehow this password that lets us get by poisoning our neighbors is a real problem for me.”

In response to the record level of nitrates, the Des Moines Water Works switched on its $3.7 million nitrate-removal facility for the first time since 2007. The system, which is believed to be the largest in the world, costs $7,000 a day to run and the bill for the nearly three months of operation amounted to over half-a-million dollars.

Becky Ohrtman, Source Water Protection Coordinator - Iowa DNR:  “Operating and maintenance, that’s very costly when you start putting in treatment systems.  A lot of communities will look at drilling a new well but that’s not a guarantee if they drill a new well that it’s not going to be drawing a contaminant such as nitrates into that new well.”

Becky Ohrtman is the Source Water Protection Coordinator for Iowa’s Department of Natural Resources.  According to Ohrtman, 30 percent of Iowa’s 880 municipal water supplies are highly susceptible to contamination from nitrates.  Many of those municipalities serve small communities, where an expensive nitrate removal system would be unfeasible.

Becky Ohrtman, Source Water Protection Coordinator - Iowa DNR:  “Most communities that are proactive will say, I want to take care of this before they reach the maximum load that they’re allowed to. EPA designates you can have 10 mcl is what the nitrate level is and so once they hit that then they have to find alternate sources of drinking water for their community.   It’s kind of like planting the tree.  The best time to plant a tree is 20 years ago.  The second best time is today.”

Over 70 percent of Iowa’s drinking water comes from groundwater which is tapped by drilling wells.  Because it is subsurface, does not mean it is pollution free.

Jeff Metheny, Water Superintendent, Griswold, Ia: “Every town does testing.  They regulate how much you have to test according to where your levels are.  So since we’re at an 8 average test every month we send a sample in.  That gets reported to the DNR.  We at Griswold, we test it ourselves every day just for our knowledge.  We’re not required to do that but we test every day.”

Perilously close to test numbers that would cap its wells, the town of Griswold turned to the Iowa DNR to explore possible solutions.  With a population of only around a thousand, less expensive solutions aimed at preventing contaminated water rather than treating it were explored.    

Becky Ohrtman, Source Water Protection Coordinator:  “Our primary objective when we go into a community that has an existing contaminant problem is to identify if that contaminant is a point source or a non-point source and then to try to better define the capture zone area of where their drinking water is coming from.” 

The capture zone is the area where the well draws its water.  Once a capture zone is identified the source of the pollution can be determined and addressed. 

In Griswold it was found that the source of contamination was determined to be agriculture.  But a solution proved elusive until area farmers were invited to help develop a strategy that would reduce the amount of nitrates entering the water supply..

Drue Kirchhoff, Griswold SWP Chairman: “We were just trying to do it all ourselves and once we asked them it was like they come in and they were so much enthused about helping protect our water, not only the city’s water but they’re also, since we’ve started this they have started doing it in other areas around Griswold that’s not in our capture zone.”

The solution reached in Griswold was to plant cover crops in the identified capture zone.  According to the Iowa Nutrient Reduction Strategy; 92 percent of the nitrates in Iowa’s waterways comes from non-point sources and cover crops are the best single farming practice to keep both soil and nitrates from running off farmland.  The finding is the culmination of two years of work by the Iowa Department of Agriculture, the Iowa Department of Natural Resources and Iowa State University,

Kenny Cousins, Griswold, Iowa:  “We had some land that lays around the city wells and we’re doing a cover crop to try to control the nitrates in the water, the nitrates in Griswold water has been moving up slowly.  It’s not dangerous levels yet but we’re trying to get ahead of it before they do.”

Cousins chose a cover crop of ryegrass which was seeded by plane on standing corn.  It is not the first conservation measure he has adopted to protect Griswold’s water supply. 

Kenny Cousins, Griswold, Iowa:  “we put a buffer strip around here, it’s a 200 foot radius around the well, probably 15 years ago, something like that thinking at that time it would help and it probably did help some but now we’re putting cover crops in to help control the nitrates.  And we’ve also gone to spring applied anhydrous plus another split application where we’re putting on some more liquid in.”

There are many solutions to the puzzle of how to protect municipal water supplies.  Next week we’ll look at some of the alternative cover crops farmers are planting as well as other conservation practices employed by rural communities to keep nitrates out of their water.

For Market to Market, I’m Paul Yeager.

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