People all over Minnesota are getting more serious about how we think about nitrates and when or if we should change our behaviors to reduce how much nitrate we are exposed to via our drinking water.
The fact is nitrates do occur naturally in our soils and water due to the decomposition of plants and other biological process; however, it’s also true that human activities – like spreading manure, using drain field septic systems and fertilizing our lawns – contribute to high nitrate levels in our ground and surface water. That doesn’t mean that we need to stop those activities, but we do need to be more aware and critical of how we manage our nitrate impacting activities.
One way that Minnesotans are talking this issue is by identifying the areas in the state where coarse, sandy, permeable soils allow water and the nitrates they can carry to quickly get into our water supplies. In these areas, the new Groundwater Protection Rule directs farmers and landowners to follow best management practices (BMPs), such as not spreading manure and fertilizer after the growing season is over, that reduce nitrate runoff into water.
Most of Hubbard County has been identified as having these soil types, so farmers will be asked to voluntarily follow the suggested BMPs, as defined by the rule and the Minnesota Department of Agriculture (MDA).
I bet you are also wondering how Hubbard County’s current nitrate levels compare with known safe levels. We only know the data available from what is tested. When the MDA sampled wells in southern Hubbard County in 2016-17, they found about 10 percent of wells tested had nitrate levels over 10 milligrams per liter, which is the threshold for safe human consumption.
ADVERTISEMENT
Hubbard County Soil and Water Conservation District (SWCD) offers free nitrate testing every first Friday of the month from 9 a.m. to 2 p.m. in our Park Rapids office. We will test as many samples as come in from residents within the county, and it takes about 5 minutes per sample.
If your nitrate levels test high, we will provide information about under the sink and household water filters that remove the nitrates as well as other possible contaminants from your drinking water.
When returning landowners bring us a raw water sample to test alongside a filtered water sample, we usually see nitrates reduced to around 1mg/liter or less. These filters are pretty amazing and are one step individuals can take to ensure their household drinking water is safe.
What else can small landowners do? Research tells us that nitrate levels over 3mg/liter are almost always due to human contributions. That includes the nitrate fertilizers we use on our lawns, flowers, gardens and farm fields. Nitrates are important for plant function and growth, they should be applied to plants during or just before the most intense growth of the season, not after.
Another source that we don’t talk about much is human waste. Pumping our septic systems and keeping them in good working order does a lot to reduce nitrates in the near surface water tables.
My favorite thing that we can do is planting rain gardens and buffer gardens between sources of runoff in our yards and farm fields and the water resources nearby. A good buffer will catch those nitrates and other contaminants before they wash off the land and into open waters, and they will also provide food and habitat for all your favorite birds, butterflies, and other pollinators.
ADVERTISEMENT
The problem of increasing nitrates in our groundwater is caused by behaviors that we all have some control over. If you are concerned as a homeowner, a farmer or a lakeshore owner, then visit your local SWCD. We want to help you use your land in a way that is productive for you and that contributes to growing healthy soil and water resources.
Crystal Mathisrud is manager of the Hubbard County Soil and Water Conservation District. Its mission is to provide leadership, education, technical advice, financial assistance to landowners, cooperating agencies for various programs and projects to pursue the sustainable management, wise use and protection of the district’s soil, water, forests, wildlife and recreational resources.
