What are we drinking? Rising nitrate levels in tap water are cost problem for homeowners
ST. PAUL — Tim Figge won’t let his grandchildren drink water from his home.
Like a growing number of Minnesotans, the Dakota County resident has seen the nitrate level in his private well water increase to unsafe heights.
In 1988, nitrate in his well at his home outside Hastings registered below 1 milligram per liter, but by 2013, it had spiked to 10 milligrams per liter, a level considered unsafe by the U.S. Environmental Protection Agency.
“I’m 62, so I’m not going anywhere,” Figge said. “But I would like to see my grandchildren drink water from Grandpa’s tap, and that’s not happening right now.”
As Minnesota looks to protect and improve the quality of its drinking water, rising nitrate levels are emerging as a growing and costly challenge to homeowners and municipalities alike.
Nearly 100,000 Minnesotans in more than a dozen communities and an unknown number of private well owners have already had to address unsafe levels of nitrates in their drinking water.
The cost of these fixes can range from a few dollars to a few thousand dollars per household depending on the level of contamination and what needs to be done. The city of Hastings, for example, spent $3.5 million to upgrade its treatment facilities to reduce nitrates in its drinking water, while on the individual level, private well owners such as Figge can spend $700 to install a reverse-osmosis system to do the same.
The Minnesota Department of Health reported in May that a 2014 study of nearly 1,000 communities across the state found more than 60 had elevated nitrate levels — 3 milligrams per liter or more — in their drinking water. Fifteen had levels of 10 milligrams per liter or more — concentrations that can be dangerous for infants and pregnant women.
Nitrate is an organic compound containing nitrogen and oxygen. It enters the aquifers many communities tap for drinking water mainly through the runoff of fertilizers, animal waste and failing septic systems.
High levels in drinking water can inhibit the blood’s ability to carry oxygen throughout the body. Nitrates are particularly dangerous to infants and can lead to a condition called “blue baby syndrome,” which Minnesota hasn’t seen since the 1940s.
High levels of nitrate also can be an indicator that other contaminants are in drinking water. Cold Spring, Hastings, St. Peter and other Minnesota cities have had to drill new wells, upgrade treatment plants or install new transmission lines to blend water in order to address nitrates.
Gov. Mark Dayton, conservationists and public health officials largely blame farm runoff for increasing nitrate levels in Minnesota’s drinking water supply. This year, the Legislature took a major step to reduce that runoff by tightening rules requiring vegetative buffer strips between row crops and state-protected waters and public drainage ditches.
Previous buffer requirements have been inconsistently enforced, and only a fraction of public drainage ditches required the protective strips.
The law, however, was not without controversy. Farmers say the one-size-fits-all approach of buffer strips isn’t necessary in an age of increasingly precise agricultural practices. They fear the required buffers will mean the loss of productive farmland and — with it — income.
At a recent visit to Vermillion Elevator, an agriculture supply in rural Dakota County, Hampton-area farmer Al Bester said agriculture gets a bad rap when it comes to water quality.
“We get blamed for everything,” Bester said.
Several communities with elevated nitrate levels draw their drinking water from the Prairie du Chien-Jordan Aquifer, which lies beneath much of southern Minnesota, Iowa and Wisconsin. About two-thirds of Twin Cities communities tap aquifers for their water, too.
In the east metro, cities from Scandia and Lake Elmo to Hastings and Rosemount have all reported elevated nitrate levels in their drinking water sources. And Hastings probably has been the hardest hit.
A little more than a decade ago, Hastings saw nitrate levels in its groundwater rise toward unsafe levels. City officials believed farm runoff, likely delivered to the aquifer by the Vermillion River that cuts through miles of farmland, was to blame. In 2008, the city spent $3.5 million on a water-treatment plant upgrade to lower nitrate levels, an estimated cost of $410 per household.
That bought what Mark Peine, the city’s public works supervisor, described as essentially a “very large water softener,” which uses positively charged ions to remove nitrates from the city’s source water. Today, Hastings’ treated drinking water has a nitrate concentration of about 4 milligrams per liter, down from more than 8 milligrams per liter before the plant upgrade.
Although nitrate levels in the city’s water before treatment appear to be on the decline, Peine said Hastings is ready with plans for more treatment upgrades should they be necessary. “We are watching it very closely,” he said.
Other communities are doing the same.
In Rosemount, public works director Patrick Wrase said the city’s wells in residential areas test well below the standard for nitrate. However, nitrate levels increase in water samples taken from wells in the more undeveloped parts of town to the east toward Hastings.
Wrase said Rosemount could blend water from multiple wells to address the higher nitrate levels, but doesn’t need to yet.
“We have options right now. We don’t believe it will reach levels where it will become a concern,” Wrase said. “As Rosemount becomes less agricultural and more residential, it is likely the nitrate levels will decrease.”
Private residential wells such as Figge’s might be at the most risk to nitrate contamination.
A fall 2014 survey of 710 rural Dakota County wells found one in five had levels exceeding the 10-milligrams-per-liter standard. A similar 2013 survey of other rural wells found 32 percent fell short of standards for clean drinking water.
County officials currently are studying drinking water in Inver Grove Heights, a city with one of the highest concentrations of private wells.
Jill Trescott, the county’s groundwater-protection supervisor, said a well’s age and proximity to contaminants can play roles in the amount of nitrate found in the water. About 40 percent of Dakota County’s residential wells were installed before 1974, when the state adopted well standards. Those older wells are likely shallower and not built as diligently.
“If there’s any kind of contamination that’s happening right at the surface, the contamination is going to hit the older well a lot faster than it would with a newer well that has been constructed according to modern standards,” Trescott said.
But even more modern wells are susceptible, and removing nitrate from a private well is costly. Figge recently installed a $700 reverse-osmosis system to clean up his water.
“We are in an area — Dakota County — where the soil conditions are tremendously sandy,” he said. “So it doesn’t take a lot for nitrogen and other waterborne products to get in there.”