Last month I attended the annual member meeting of the Association of State Drinking Water Administrators (ASDWA) in Washington, D.C. This group consists of all my counterparts in other U.S. states and territories. It is a great opportunity for me to learn about how other states are working to address similar challenges to what we may be facing in Colorado. This year three states, Wisconsin, Minnesota and Nebraska, shared information about what they are doing to address high nitrate levels in groundwater. Significant portions of these states experience this problem that impacts both community and non-community groundwater systems, plus private wells. Nitrate is known as an acute health risk contaminant for infants. However, more research is being done about chronic impacts as well.
Though our nitrate concerns in Colorado tend to be more localized, we have had a number of water systems exceed the nitrate Maximum Contaminant Level (MCL) of 10 mg/L over time as well. In the 2010s almost 50 communities had a nitrate MCL violation and 65 non-community water systems also had nitrate MCL violations. Fortunately, those numbers are considerably lower so far in the 2020s. A nitrate MCL violation represents a serious challenge for those systems as immediate Tier 1 public notice must be provided advising customers to stop drinking the water. Addressing this issue can be time consuming and expensive. If treatment is needed then ion exchange or reverse osmosis is typically used, which requires a higher level operator for the system and creates a concentrated waste that must be handled and disposed of as well on top of all the added cost for the treatment infrastructure.
Given these concerns, I thought I would share a brief summary of this issue in these states and some of the steps they are taking to address this challenge
Wisconsin is “America’s Dairyland” and #2 state in the country in growing potatoes, which is a nitrate intensive crop. Ten percent of its 800,000 private wells exceed the nitrate MCL which would cost over $400,000 million to replace those wells. Wisconsin public water systems receive 30 to 40 new nitrate MCL violations every year, dwarfing our problem in Colorado. While there is a sense that this problem cannot be fully “solved” in the near future, Wisconsin is taking numerous steps with many partners and projects help with it. Most of these efforts come from their source water protection protection program and include:
- Teacher workshops through universities educating kids about groundwater with specific lesson plans and hands on models
- Nitrogen budget and leaching calculator
- Decision tools that can evaluate application rates
- Developed a well water quality map view with largely private well data
- Evaluating nitrate depth guide drilling to often deeper unimpacted locations
- Numerous projects with with farmers and universities
- Replacing wells
In Minnesota corn and bean crops are main nitrate sources and the southeastern portion of the state with its karst geology is most vulnerable to contamination. Minnesota has fewer violations than its neighbor but last year, 60% of those water systems had to install treatment. Minnesota enacted a new groundwater protection rule that limits fall fertilization applications and is working on a mitigation process in vulnerable areas. The state also developed a number of programs designed to help private well owners and developed simple communication materials. These efforts involve:
- Well inventory including private wells
- Substantial Outreach/communications including realtors
- Free nitrate testing
- Free treatment available, with 140 reverse osmosis systems installed
- Health-based guidance including:
- New studies showing nitrate association with numerous conditions
- Historical information regarding blue baby syndrome cases in the 1940s
Nebraska recently commissioned a study of nitrate in groundwater showing large areas of the state with nitrate levels above 10 mg/L. They have about 170 public water systems currently treating for nitrate. Nebraska developed a predictive model to predict how far away a system might be from having a source that exceeds the nitrate MCL and categorized the systems with certain actions:
- 0-3 years out = get started on funding applications
- 3-6 years = provide assistance
- >6 years = Emphasize source water protection
Nebraska offered free testing to private well owners and a rebate program for reverse osmosis treatment systems. They also developed an outreach toolbox with an emphasis on risk assessment.
In Wisconsin and Minnesota EPA got involved to pressure the states to take action to address this acute health risk, and also partnered with the states in the efforts to address it. As you can see, tackling this challenge requires a great deal of effort. I am thankful that we can draw on the experiences in these states to help us when we face similar issues in Colorado. Thank you for your efforts in keeping our drinking water safe.
➽ Ron Falco, P.E. Safe Drinking Water Program Manager
