An environmental group has released a online digital water atlas reporting on the levels of nitrates and phosphates in four states.
The Environmental Working Group recently unveiled its findings, which shows a “close link between heavily fertilized cropland in Illinois, Iowa, Minnesota and Wisconsin and nutrient pollution endemic to the region’s waterways and drinking water supply.”
“EWG’s water atlas relies on thousands of data sources to give people the ability to visualize where the worst nitrate and phosphorus pollution occurs in counties with large applications of fertilizer,” said Soren Rundquist, EWG’s director of spatial analysis. “It’s a great resource for anyone concerned about farming’s impact on water quality.”
In Bremer County, one conservation board director wonders, however, what status many of the numbers provided by the EWG reflect – before or after a water supply is treated.
Andrew Hockenson, with the Bremer County Conservation Board, said cities and property owners have “their work cut out for them” when trying to handle nutrients in the water supplies.
“We track and do monthly samples on our well at North Cedar Park, which is north of Plainfield, and that’s from a well,” Hockenson said. “Those numbers are similar to what they’re seeing here in the upper levels, eights or so, nines.”
Mike Miner, the director of the Butler County Conservation Board, wanted to take a closer look at the EWG report before commenting directly on it.
However, he said some of the numbers Waverly Newspapers recited do sound high, but he wanted to get a better context.
He said that the Butler board tries to impact water supplies in its parks and properties as little as they can.
“On any type of vegetation management, we try to go with as chemical-free as possible,” Miner said. “We do most of our work with natural things for dealing with any issues within parks and wildlife areas, whether they’re along a stream bank or near a river or off on their own.
“We test our wells on a regular basis on our campgrounds just to monitor where we’re at and make sure that the water being used by our visitors are within the corrected, or within the levels required.”
Nitrate and phosphorus are the main components of the commercial fertilizer and manure farmers use to provide nutrients to crops – mostly soybeans and corn, in the four states included in the water atlas. Without careful farm management of fertilizer and manure, excess phosphorus and nitrate runoff fields into streams, rivers and lakes or seep through the soil into groundwater.
The water atlas’s two interactive maps incorporate phosphorus and nitrate data from 8,200 state and federal water monitors and nitrate data from 3,794 community water systems serving 19 million people in the four states. The maps reveal high levels of phosphorus pollution in counties with intensive fertilizer use throughout the Upper Mississippi River Basin.
In Illinois, Iowa, Minnesota and Wisconsin, 80 percent of surface water monitors and 83 percent of groundwater monitors with elevated phosphorus levels of at least 100 micrograms per liter, or µg/L, were located in counties where more than 70 percent of cropland is fertilized.
For local test sites cited in the maps by the EWG, Waverly’s municipal water system has averaged 7.75 mg/L of nitrates out of 140 samples from 2012-19. A chart showed the highest levels are near 10 mg/L, while the low end is around 5.5 mg/L. There was no phosphorus test data available for the city’s system.
The City of Waverly is in the process of upgrading its Water Pollution Control (WPC) facility. As part of the nearly $10 million loan from the state to help pay for the project, nearly $1 million in State Revolving Fund (SRF) moneys is going toward a wetlands project that will be located north of the intersection of 20th Street and Fifth Avenue Northwest.
Waverly Newspapers reached out to Waverly city officials for further comment, and didn’t get a reply by press time.
Other sites in Bremer County showed that Well No. 6 in Waverly had an average of 6.75 mg/L of nitrates and 40 µg/L of phosphorus. The Avenue of the Saints Lake west of Waverly shows only 0.29 mg/L of nitrates on average but had 230 µg/L, ranging from 88 to 604 µg/L.
The water supply for the Saints Avenue Apartments south of Waverly had an average of 8.25 mg/L of nitrates, with no data on phosphorous.
Janesville had three reporting stations. The city’s water supply showed an average nitrate level of 3.63 mg/L, while Well 3 had 12 mg/L of nitrates and 30 µg/L of phosphates. The Cedar River at Janesville had an average of 7.02 mg/L of nitrates and 200 µg/L of phosphorus.
Meanwhile, Plainfield had nitrate levels averaging 7.65 mg/L, Denver had 0.78 mg/L in its city supply and 0.1 mg/L at Meadow Lane Mobile Home Park, Readlyn showed 0.88 mg/L in nitrates, Tripoli’s nitrate level was 0.23 mg/L, and Sumner had 0.3 mg/L of nitrates.
Hockenson, the Bremer conservation director, said there is “good cause” to keep checking water nutrient levels.
“They can fluctuate, and they’re getting close to that high level, acceptable level,” he said.
Over in Butler County, the nutrient levels in the Shell Rock River at Shell Rock had a wide range. The river averaged 5.3 mg/L of nitrates and 380 µg/L of phosphorus, but the minimum levels were 0.16 mg/L and 50 µg/L respectively with maximums of 16 mg/L and 17,000 µg/L respectively.
Clarksville’s water supply had an average of 4.51 mg/L of nitrates with no report of phosphorus.
Excess phosphorus in freshwater feeds algae blooms. Not all algae outbreaks are toxic, but those that are can harm humans and animals. And even algae blooms that are not toxic can make waterways unfit for fishing and swimming.
The water atlas confirms previous EWG investigations revealing that drinking water nitrate contamination is a serious and worsening problem. In the four states, 86% of the water systems contaminated with nitrate levels at half or more of the federal legal limit are located in counties where at least 70% of the cropland is fertilized.
Under the 1974 federal Safe Drinking Water Act, the legal limit for nitrate (measured as nitrogen) in community water systems is 10 milligrams per liter, or mg/L. But more recent studies show strong evidence of an increased risk of colon and rectal cancers, thyroid disease and neural tube birth defects at levels of 5 mg/L or even lower.
More than 2.8 million people are served by water systems that tested at or above 5 mg/L at least once over the eight-year period covered by the records used for the water atlas. One out of every 400 water systems detected nitrate at or above 10 mg/L at least once. These systems serve more than 490,000 people, with 32% of them in Minnesota and 29% in Iowa, followed by Wisconsin, with 22%, and Illinois, with 17%.
The water atlas can be seen at https://www.ewg.org/research/ewg-water-atlas-reveals-nitrate-phosphorous-water-pollution-four-upper-mississippi-basin.
Nitrogen and phosphorus runoff from agriculture in these four states is the primary cause of a notorious annual hypoxic zone off the coasts of Louisiana and Texas. During the summer, that part of the Gulf of Mexico is effectively dead, with devastating effects on Gulf fisheries and ecosystems – and the maps show the pollution problem persists.
“As EWG’s water atlas clearly demonstrates, surface and groundwater resources are vulnerable to heavy fertilizer use in Illinois, Iowa, Minnesota and Wisconsin,” Rundquist said.
For control of the nutrients in water, both Hockenson and Miner suggest property owners contact their local Iowa State University Extension office or USDA Natural Resources Conservation Service branch.
“As a conservation board, we really don’t get involved with it that much,” Hockenson said. “On our properties, we try to have those wetland areas and if we can build or acquire property to keep it a wetland, that definitely helps.”
Miner added his board provides information on what’s out there.
“Just some practices on what they can use,” he said.