Olmsted County Nitrate in Groundwater-Private Well Township Testing Results

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1 Olmsted County Nitrate in Groundwater-Private Well Township Testing Results Kimberly Kaiser, Hydrologist September 20 th Presentation to the Olmsted Environmental Commission Fertilizer Management Unit

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3 Why do we care about nitrate in drinking water? 10 mg/l or (ppm)nitrate (as nitrogen) MN health risk limit Blue Baby Syndrome - Methemoglobinemia Interferes with ability of blood to transport oxygen Infants (0 to 6 months)

4 Nitrogen Fertilizer Management Plan The NFMP is the state s blueprint to minimize groundwater impacts from the use of nitrogen fertilizer. Voluntary and regulatory components The plan calls for an assessment of nitrate concentrations in private wells (township scale) and public wells. Draft Nitrogen Fertilizer Rule:

5 Assessment: Groundwater Testing Private wells Data source: MDA Township Testing Program Public wells Data source: MDH Drinking Water Protection Program

6 Township Assessment: NFMP Levels Prevention Mode Mitigation Level One Mitigation Level Two Mitigation Level Three Mitigation Level Four 1. Nitrate Levels <5% 10 mg/l 5% 10 mg/l Or 10% > 7mg/L Increasing 10% 10 mg/l 10% 10 mg/l 15% 10 mg/l 2. BMP Adoption Acceptable or Undetermined Not Acceptable Regulatory Status Voluntary Regulatory

7 Township Testing Starting Point

8 Township Testing Assessment: Two Step Process Work with local partner (SWCDs or County) All well owners are offered a free nitrate test kit Homeowner collects sample and mails it in Step 1 Initial test Offer follow-up nitrate and pesticide samples Samples collected by trained staff Data and site visit information analyzed Step 2 If nitrate is detected

9 Step One: Initial sample Work with Local Partners Olmsted County Environmental Services Townships vulnerable to high nitrate concentrations. Mailing list development and coordinate with lab. Public Outreach 11Townships tested

10 Step One: What s in the Initial Nitrate Kit? Well owners receive from certified lab: Invitation letter Sample bottle Sampling instructions Prepaid mailer Survey about their well (construction type, depth, age and potential nitrate sources)

11 Kits Sent and Returned Township Kits Sent Water Samples Returned to Lab Return Rate Dover % Elmira % Eyota % Farmington % High Forest % New Haven % Orion % Oronoco % Pleasant Grove % Quincy % Viola % Total %

12 Olmsted Initial Results Townships Total Wells* Values Percentiles Number Percentage Min Max Mean 50th (Median) 90th Nitrate as Nitrogen mg/l or parts per million (ppm) DOVER 49 <DL % 10.2% ELMIRA 50 <DL % 6.0% EYOTA 54 <DL <DL % 5.6% FARMINGTON 56 <DL % 25.0% HIGH FOREST 143 <DL <DL % 1.4% NEW HAVEN 169 <DL <DL % 3.6% ORION 73 <DL <DL % 1.4% ORONOCO 255 <DL <DL % 2.0% PLEASANT GROVE 100 <DL <DL % 3.0% QUINCY 35 <DL % 8.6% VIOLA 73 <DL % 6.8% Total 1057 <DL <DL % 4.7% *All well types are reported. Wells (hand dugs, etc) will be removed after the 2nd round of sampling if source of nitrogen is not likely nitrogen fertilizer.

13 Step Two: Follow-up sampling Step 2 If nitrate is detected Offer the follow-up sampling to homeowners with detectable nitrate. Collect follow-up nitrate and pesticide samples Samples collected by trained staff Inventory other possible nitrate sources

14 Step 2 Follow-up Sampling Township Initial Well Dataset Number of Wells > Detection Limit Percent of Wells > Detection Limit Follow-Up Sampling Conducted % Follow-up Sampling % of Original Sampled Wells Dover % 16 47% 33% Elmira % 13 39% 26% Eyota % 4 25% 7% Farmington % 16 40% 29% High Forest % 18 44% 13% New Haven % 26 53% 15% Orion % 9 38% 12% Oronoco % 51 57% 20% Pleasant Grove % 7 32% 7% Quincy % 11 44% 31% Viola % 11 30% 15% Total % % 17%

15 Step Two: MDA Follow-up Sampling A. Document well information Well type, depth and construction B. Inventory other possible nitrate sources close to the well Construction problems Septic sources Animal sources Other sources C. Collect Nitrate and Pesticide Sample D. Data Analysis Have the results changed significantly since the initial sample? Are the wells >5mg/l potentially impacted by fertilizer? If not, they are removed from the dataset.

16 Unsure of Water Source Irrigation Wells or Spring Source? No Unique Well ID & Well Not Seen & Constructed before 1975 Point Source No Unique Well ID & No Site Visit & Insufficient Information Well Construction Problem Hand Dug Wells

17 Reasons wells were removed from dataset Township Point Source Well Construction Problem Hand Dug Wells Shared Wells Unsure of Water Source No Unique ID & Well Not Seen & Constructed Before 1975 No Unique ID & No Site Visit & Insufficient Information Total Removed % of Initial Results Removed Dover % Elmira % Eyota % Farmington % High Forest % New Haven % Orion % Oronoco % Pleasant Grove % Quincy % Viola % Total %

18 Initial and Final Well Comparison Initial Well Dataset Final Well Dataset Township Total Wells Percent of Wells 10 mg/l Nitrate-Nitrogen Total Wells Percent of Wells 10 mg/l Nitrate-Nitrogen Dover % % Elmira % % Eyota % % Farmington % % High Forest % % New Haven % % Orion % % Oronoco % % Pleasant Grove % % Quincy % % Viola % % Total 1, % %

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21 References for MDA monitoring For more information: Township Testing Program Visit Nitrogen Fertilizer Management Plan Visit Draft Nitrogen Fertilizer Rule: Visit Private Well Pesticide Sampling Visit Pesticide Monitoring Well Network Visit