DNR targets groundwater threatsPublished 10:20am Thursday, February 13, 2014
By Dan Gunderson
MPR News, 90.1FM
Park Rapids, Minn. — A growing awareness about Minnesota’s groundwater challenges is about to hit the residents of Park Rapids in the wallet.
Fees for city water are going up roughly 25 percent to help pay for a $2.5 million treatment plant. The new plant is needed because the city’s old water supply has become too contaminated with nitrates from fertilizer applied by farmers in the area.
Dick Rutherford, who owns a business and two homes in town, is angry that city residents are paying for pollution caused by agriculture.
“We know where it’s coming from,” he said. “It’s the farmers that are putting this stuff in the ground. I don’t feel we should be paying for the whole thing, I don’t think we should be paying for any of it. We should be billing these people that are putting the irrigators in.”
Irrigation is essential for growing crops in parts of Minnesota. But in the north central part of the state near this city of 3,700 residents, irrigated farm fields contribute to groundwater pollution and threaten a unique fishery.
That’s why what is known as the Straight River watershed, which includes Park Rapids, is one of three groundwater management areas the state Department of Natural Resources will focus on over the next year. As pressure builds on the groundwater available, the state’s goal is to bring farmers, businesses, residents and officials together to figure out how to deal with it, possibly even to restrict use in some cases.
Although the effects of irrigation were first talked about years ago because the Straight River, a valued trout stream, was getting damaged, the biggest single impact recently has been the need for the new water treatment plant Park Rapids will bring on line next month.
The city never needed to treat its water before, said public works superintendent Scott Burlingame. It simply pumped clean plentiful water from a shallow aquifer.
“Water rates were cheap, everybody was happy with that,” Burlingame said. “So things have changed.”
What changed is the level of nitrates in the water. Nitrates come mostly from the nitrogen fertilizer farmers use on irrigated potato and corn crops grown on top of the shallow aquifer.
Nitrate levels in existing city wells, which tap the aquifer about 70 feet below the surface, approach or exceed the safe drinking water standard. Click to view full aquifer map
That forced the city to drill a well into a deeper aquifer, about 120 feet down. That aquifer is at least somewhat protected from nitrate contamination by a layer of clay above it. Hydrologists hope to map the aquifer in the next few years to better understand how water moves and interacts with the shallow, polluted aquifer.
“There’s a lot of water in that well and good quality water,” Burlingame said.
The new treatment plant will remove iron and manganese from the water. Those naturally occurring metals are not a health risk but can stain sinks, showers or clothing.
Based on national water use averages, a typical family of four would see its annual water bill rise about $130 as a result.
Over the past 25 years, farmers in the Park Rapids area sank dozens of irrigation wells because water and lots of fertilizer turned poor, sandy land into highly productive farmland for potatoes and corn.
DNR groundwater specialist Michele Walker said abundant groundwater only 70 feet below the surface made it easy for farmers to expand.
“Back in 1988 we had about 100 permits,” Walker said. “Now we have about 275.” The state requires a permit from the DNR for any well pumping more than 10,000 gallons a day or a million gallons per year.
Nearly eight billion gallons of water are pumped from wells in the Straight River watershed each year, 90 percent of it for crop irrigation.
The sandy soils drain quickly. That’s good for potatoes because wet soil can cause disease.
“The problem is that these soils are very sandy, and if you happen to put your nitrogen out and we get a gully washer, it’s going to go somewhere,” Walker said.
Walker said in the Straight River watershed, it’s likely the nitrogen fertilizer moves down through the soil to the aquifer that in some places is only 40 feet down.
Minnesota Department of Agriculture test wells show nitrate levels two to three times the safe drinking water level. Those wells are tested at the top of the aquifer, closest to the surface where nitrates are most concentrated. But in 2012, the department tested 72 private wells in Hubbard County, wells that typically tap the aquifer farther down, and still found 10 above the safe level.
Elevated nitrates in drinking water are a problem because they can cause blue baby syndrome in infants under 6 months who are bottle fed.
Long-term health effects for older children and healthy adults exposed to elevated levels of nitrate in their drinking water are not yet known or agreed upon in the scientific community. But the National Cancer Institute suggests a link between elevated levels of nitrate in drinking water and an increased risk of non-Hodgkin’s lymphoma.
Even before the creation of the DNR’s groundwater management area, the state Department of Agriculture has been working with farmers in the Park Rapids area to reduce water and fertilizer use.
Fifty farmers in the area took part in a monitoring and education program last year, said Luke Stuewe, who coordinates the program for the department.
“Sixty-five percent of the growers involved in the program found they could make adjustments to their rate and the majority of those were reductions in rate,” Stuewe said. “So they found they could do something differently and ultimately have a lower amount of nitrogen going down on the field.”