Earlier this week, Bluestem posted about the warning the City of Fairmont issued about infants drinking city water in our post Paging Rep. Torkelson: City of Fairmont issues water advisory, nitrate levels unsafe for infants.
How did the nitrates get into the city's water? On Friday, the Fairmont Sentinel reported in Nitrate level high in city water:
. . . But what caused the MCL for nitrates in Fairmont's water?
Rainforth talked with several industry professionals who concurred that the sustained wet weather pattern is likely the cause. Water flowed over the George Lake dam all last winter, the first time in anyone's recollection, he said. Couple days of rain and drizzle with spring fertilization, and problems can arise.
"The source of most nitrates in surface water is fertilizer," Rainforth said. "It's running off every yard in town that applies fertilizer."
Runoff from fertilized green spaces eventually ends up flowing into our lakes and creeks, which provide the source for the city's drinking water.
Rainforth said that the elevated nitrate level "has never happened before in Fairmont."
Because consuming water with the MCL of nitrate impacts the health of the youngest of infants, it raises concerns.
"It's easy to have this become an emotional issue," Rainforth said. "But the MCL is established at the lowest concentration that any health effect has ever been documented. To say that an infant will experience an adverse health effect is incorrect, but there is a slight possibility that they may."
He also cautioned against jumping on the hysteria bandwagon.
"I would urge people against listening to self-proclaimed experts who may sensationalize the facts," he said.
How much do lawns contribute to nitrate pollution in spring?
We've bolded a statement about the source of the fertilizer that made us pause for several reasons. First, the University of Minnesota Extension Service's lawn care webpage recommends that the best time to fertilize lawns is late summer.
Second, as the Extension's post Turfgrass and Water Quality notes that there's very little stormwater run-off from a healthy lawn:
Research over the last twenty years has demonstrated that storm water runoff from a healthy, dense lawn growing on soils of even moderate compaction rarely occurs, even on modest slopes. In fact, in all but very intense rainfall occurrences, stormwater runoff from a healthy, dense lawn is at or near zero. However, some notable exceptions to this include very steep slopes, saturated soil conditions, severely compacted soils and frozen ground. . . .
The dense matrix of grass shoots, stems and leaves of an actively growing, healthy lawn significantly slows down any runoff that might occur, thereby increasing potential water infiltration. Slower moving runoff also has reduced capacity to carry sediment or other soil particulate matter, hence reducing the erosive effects of faster moving water. Not only does increased water infiltration help protect surface water quality; it also helps recharge groundwater supplies. The dense, fibrous network of roots help trap and remove nutrients and other pollutants from water moving down through the soil. This filtering effect can actually improve water quality as it moves through the turfgrass root zone. . . .
We reached out to Sam Bauer, an Extension educator who is on the Turfgrass management team. Bauer extolled the ability of healthy lawns to retain nurtients, comparing to buffer strips.
This being the case, where might the fertilizer that entered Fairmont's Chain of Lakes have come from? Bauer suggested that a more likely source of the fertilizer entering the watershed would be from farm fields, since the young plants simply had not yet developed root systems robust enough to retain nutrients, either from manure or commercial fertilizer.
We looked at a map in the Beacon system that indeed showed that a drainage ditch enters Budd Lake (see screengrab above), and possibly creeks that are ditches upstream (our copy of the Delorme Atlas and Gazetteer of Minnesota Detailed Topographic Maps suggests that several streams enter Budd Lake from the west).
Did agriculture contribute to this problem?
Had farmers in Martin County been planting before the rains? On May 12, the Minnesota Farm Guide reported in Martin County farmers deal with rain before getting back in fields:
Drainage systems were a necessity in southwest Minnesota following heavy rain during the last week of April.
Cold, wet and windy conditions kept farmers out of the fields. . . .
We felt like we were in London because it rained almost every day,” said Dan Helvig on May 3.
The Helvig home farm received 2-2.75 inches of rain during April 19-30.
“You can see the creeks and culverts and all of these public waterways that have been built for years are being well-used,” he said.
Farmers in the Truman area began planting corn on April 11, he said. The Helvigs decided to wait until April 15 to start, and they had three to four good days of planting before it started to rain.
“Sometimes, that first rain – if it’s cold, it’s going to drop your soil temperature down fast, and that first drink of water that seed gets is cold,” said Dan, 27. “As a result, not every seed will come up at the same time, so you can have poor emergence and a little riskier planting right before a cold rain.
“It turned out that the rain was actually warm and beautiful. It was just what the corn needed. In the end, I wish I had more acres in at the time.” . . .
Truman is just up Highway 15 from Fairmont, so farmers closer to the Martin County seat were likely planting as well before the rain.
Does nitrogen leach from fields if spring rains are heavy? According to Nitrogen management in a wet spring, an article from the University of Nebraska that was published on May 13, 2016, in the Corn + Soybean Digest:
Planting may be in the front of everyone’s mind, but farmers should not lose sight of nitrogen management, particularly after the recent rains. With the extra moisture, water movement through the soil creates reason for concern. If nitrogen fertilizer was applied to corn fields either last fall or this spring before the recent rains, potential nitrogen loss is likely.
Most inorganic nitrogen is in the form of nitrate. Nitrate in soil is subject to leaching losses when excess water drains below the active rooting depth, which is about 3-4 feet for corn. In the last two months (March and April) most areas across Nebraska have seen significantly more rainfall than long-term averages for the same period, causing many producers to wonder if their fields are at risk for nitrate leaching. . . .
Because the soil in most fields has likely been fully recharged, further rainfall in the coming weeks will likely lead to more nitrate leaching. . . .
Nitrogen is a tricky nutrient and needs to be watched carefully to prevent losses to both your bottom line and the environment.
As the article's conclusion suggests, farmers would prefer that nutrients stay in their fields rather than ending up in their small town neighbors' drinking water supply. Bauer echoed this sentiment, noting that their goal is to feed people; he praised tools that producers could use to retain nitrogen for their crops, such as cover crops, buffer strips and the like.
Bluestem certainly hopes farmers will follow these practices, though the webpage for the 2013 Report on nitrogen in surface water from the Minnesota Pollution Control Agency noted:
Nitrate fertilizer efficiency has improved during the past two decades. While further refinements in fertilizer rates and application timing can be expected to reduce nitrate loads by roughly 13% statewide, additional and more costly practices will also be needed to make further reductions and meet downstream needs. Statewide reductions of more than 30% are not realistic with current practices.
To see progress, nitrate leaching reductions are needed across large parts of southern Minnesota, particularly on tile-drained fields and row crops over thin or sandy soils. Only collective incremental changes by many over broad acreages will result in significant nitrogen reductions to downstream waters.
What Bauer didn't want to see is people neglecting yard care when fingers were being unjustly pointed at lawns as the culprit for nitrate pollution. Indeed.
Fairmont's "state of the art" facility completed in 2013
Nor can the city's water plant be figured as the culprit.
On Saturday, Minnesota Public Radio's Elizabeth Dunbar tweeted:
We hope that Minnesota Public Radio's excellent news staff looks closely at this incident. Rainforth cautions against a "hysteria bandwagon." Good idea--instead, this is a wake-up call for prudence about our drinking water.
Screengrab: Budd Lake (the round lake in the middle of the image at the top of this post) is the primary source of Fairmont's drinking water.
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