Groundwater Concerns for the Redeye River Watershed Redeye River 1W1P Meeting May 23, 2019 George Minerich, MDH – Drinking Water Protection
Interagency Effort GRAPS One Coordinated Voice on Groundwater
Background Information Pollution Land Cover /Land Sensitivity Groundwater Use (Aquifer Withdrawals/Use Vulnerability) Geology/ Drinking Water Hydrogeology Information 3
Groundwater Quality Information · New Well Samples · Active Tank & Leak Sites · Private Well Sampling Initiative Contaminated Nitrate · Closed Landfills Sites · Ambient Monitoring · New Well Arsenic SSTS Samples · Ambient Monitoring Animal Pesticides · Private Well Sampling Initiative Feedlots 4
Groundwater Quantity Information Groundwater Groundwater Connected Use Trends Trout Streams Features Surface Water vs. Calcareous Fens Groundwater Lakes Animals Water Level Plants Trend Native Plant Interpretation Communities 5
Wellhead Protection Planning • Eight of the nine community public water systems, within the RRW are engaged in the wellhead protection planning process or are implementing their plans. Of the eight systems with approved plans, the vulnerability varies across the watershed from very low to high. • Two of the approved wellhead protection plans exhibit a high vulnerability in their DWSMA and considered vulnerable to contamination from the land surface, with all others exhibiting moderate to low vulnerability. • Verndale is experiencing elevated nitrate conditions, one well exceeding 10mg/l nitrate (closed by MDH order) the other above 5mg/l and climbing. City installing nitrate treatment plant.
Redeye Water Supply Management Areas • Drinking Water Supply Management Areas. There are 14 approved Drinking Water Supply Areas (DWSMA) for community public water supply systems in the watershed.
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Private Wells • The RRW has 2,135 private wells with known locations ranging from 12 feet to 415 feet deep that provide drinking water to residents. Private well users are not afforded the same water quality safeguards as people who get their water from public water systems. 10
Pollution Sensitivity of Near Surface Materials • This figure is an estimate of time it takes water to infiltrate the land surface to a depth of 10 feet.
Redeye Pollution Sensitivity of Wells Sensitivity rating and the associated recharge travel times for surficial and buried aqu Pollution Sensitivity Aquifer Recharge Time Period Aquifer Recharge Time Period Rating for Surficial Aquifers for Buried Aquifers High Hours to a week Days to Months Moderate A week to weeks Years to one or two decades Low Weeks to a year Several decades to a century
Public Health Issue: Nitrate Aquifer vulnerability Nitrate in new private wells (1991-2016) Percent of population served by CWS mg/L mg/L Source: MDA Source: MDH Source: MDH 6/7/2019 13
Nitrate • Contamination problems that arise from human activity sources. Large areas of MN geologically vulnerable to groundwater contamination from surface activities (prior map). • Nitrate is one example: We are concerned about nitrate because infants that drink water or formula made with nitrate-contaminated water can develop a condition known as blue baby syndrome, which reduces the oxygen supply in their blood. Nitrate levels are highest in the geologically vulnerable area of state (2 nd map). • We also see that the counties least served by CWS are those in the geologically vulnerable Central Sands region (3 nd map). • Fertilizer applied to land used for row- crop production is biggest influence on MN’s nitrate levels. Global markets continue to drive up the amount of MN farmland devoted to corn and soybeans, which require high fertilizer input to maximize yield. . We are highly agricultural state - MN currently ranks 3 rd and 4 th in nation in corn and soybean acreage respectively. 6/7/2019 Optional Tagline Goes Here | mn.gov/websiteurl 14
Nitrate • Nitrate-nitrogen (referred to as nitrate) is a Table 1: Summary of nitrate results in drinking water wells of the Redeye River Watershed. Depth Total Minimum Maximum Median Samples at or Samples at compound that occurs naturally and has many Completed samples concentration concentration concentration above 3 mg/L or above 10 Range (nitrate) (mg/L) (mg/L) (mg/L) (%) mg/L (%) human-made sources. When nitrate levels are above (feet) < 50 165 0 17.72 0.5 26.7 3 3 milligrams per liter (mg/L) in groundwater, human 50 - 99 697 0 24.3 0.5 6.3 2.7 activity is the likely cause (State of Minnesota 100 - 149 352 0 10.04 0.5 2.6 0.3 Workgroup). Human-induced sources of nitrate 150 - 199 158 0 7.1 0.5 1.9 0 >= 200 116 0 2.35 0.5 0 0 include animal manure, fertilizers used on Total 1488 0 24.3 0.5 6.7 1.7 agricultural crops, failing SSTS, fertilizers used at residences and commercially, and nitrous oxides from the combustion of coal and gas. High levels of nitrate are present in areas where there are both human-caused sources of nitrate and high pollution • Nitrate is one of the most common contaminants of sensitivity. groundwater in Minnesota and is a public health concern where found in groundwater used for drinking water. The SDWA standard for nitrate in The absence of elevated nitrate concentrations drinking water is 10 mg/L. Most of the samples taken throughout most of the watershed may be a function of from wells within the watersheds did not exceed the low-impact land use near the wells or the presence of SDWA standard for nitrate. favorable geochemical conditions in the aquifers
Public Health Issue: Arsenic & Manganese Percent of new private wells >10 µg/L Probability of manganese >100 μg /L in arsenic by county, Aug. 2008-Jul. 2013 groundwater Source: MDH Source: MDH 6/7/2019 17
Naturally-occurring contaminants: • Arsenic: Arsenic exposure is associated w/increased risk of cancer of the bladder, lungs, liver, and other organs; nervous system problems, skin effects, high blood pressure, and reduced intelligence in children. State-wide, 11% of wells exceed max contaminant level established for PWS. >11% in about half of MN counties. • Manganese: Can cause neurological problems, including learning and behavior problems in infants and children. In 2012, MDH developed “tiered” water guidance for manganese to provide an appropriate level of health protection for different groups based on age-related susceptibility to the harmful effects of manganese. The guidance is: • •100 μg /L for infants 12 months of age or younger who are drinking the water • •300 μg /L for exclusively breast-fed infants, children older than 12 months and adults. • Based on a statewide sample of >9,000 private wells in Minnesota, about half (49%) are estimated to exceed the 100 μg /L guidance value for manganese. Manganese distribution in groundwater is highly variable throughout the state - many areas have concentrations consistently above 100 μg /L (2 nd map). 6/7/2019 Optional Tagline Goes Here | mn.gov/websiteurl 18
MDH Priority Concerns: • Prioritize Drinking Water Supply Management Areas in the Redeye River Watershed 1W1P. • Prioritize Sealing Abandoned Wells • Prioritize Protection of Private Wells • Prioritize Protecting Noncommunity Public Water Supplies • Prioritize protection activities in highly vulnerable DWSMAs where there are not currently water quality impacts to drinking water aquifers. 6/7/2019 20
Existing Landscape: • Protection of existing land – plan development • Natural Vegetation – keep intact when possible • Water Quality - "The movement of water between ground water and surface water provides a major pathway for chemical transfer between terrestrial and aquatic systems“ (USGS Circular 1129) • What happens in the watershed directly effects what we drink! 6/7/2019 21
Questions? 6/7/2019 22
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