Nitrogen in Minnesota Streams

Transcription

1 Nitrogen in Minnesota Streams Sources, loads and transport Dave Wall with David Mulla, Steve Weiss, Dennis Wasley and David Lorenz October, 2012

2 Report Nitrogen in Minnesota Surface Waters comparing watersheds, sources, trends and solutions Major Rivers - loads and concentrations HUC8 watershed conditions N transport and transformations Trends Sources Verification of source assessment Tools for evaluating solutions

3 Collaborative Study MPCA Steve Weiss, Dennis Wasley, Tom Pearson, David Christopherson, Pat Baskfield, Mark Tomasek, et al. University of Minnesota David Mulla, Jake Galzki, Karina Fabrizi, William Lazarus, Mae Davenport, Ki-In Kim, Carl Rosen, Bjorn Olson, Geoff Kraemer USGS Dave Lorenz, Dale Robertson, David Saad, Gary Martin Metropolitan Council Karen Jensen, et al. MDA Joshua Stamper, et al. 3

4 Concern: Nitrogen in Surface Waters Downstream Loads Gulf of Mexico Lake Winnipeg In-State Concentrations Aquatic life toxicity Drinking water 4

5 Mississippi River at Iowa 211 million lbs/yr TN (avg) 77% from Minn. watersheds 75% in Nitrate form Nearly half from Minnesota River Basin Peaks April-June 5

6 Transport to Gulf of Mexico 6

7 Red River at Canada 37 million lbs/yr TN (avg) 48% from MN watersheds 7

8 Concern: Nitrogen in Surface Waters Downstream Loads Gulf of Mexico Lake Winnipeg In-State Concentrations Aquatic life toxicity Drinking water 8

9 Stream Nitrate Concentrations 90 th percentiles

10 In-state and downstream concerns N standards for MN streams under development Gulf of Mexico Hypoxia Task Force Comprehensive Nitrogen Study for Minnesota informs Minnesota Nutrient Reduction Strategy 10

11 Nitrogen Study - Key Questions 1. What are the N conditions? 2. Where is most N coming from? Geographically Sources Pathways 3. What are the trends? Next talk D. Lorenz 4. How much N is lost within surface water? 5. How much can N be reduced? 11

12 SPARROW Modeling Total Nitrogen Yield (lbs/ac) S. Central Metro 17 Southeast 9-15 Southwest 8-15 Central 3-6 Northwest 3-6 Northeast 0-2

13 Monitoring Nitrite+Nitrate-N Yield (lbs/ac) S. Central Southeast 8-9 Southwest 4-9 Central 1-2 Northwest Northeast 0.1-2

14 Sources & Pathways Nonpoint Sources U of M Dr. David Mulla et al Field/local scale research multiplied by GIS data Point Sources MPCA Permit Data Atmospheric Deposition EPA model Monitoring 14

15 Statewide N Sources to Soil cropland and other land Annual Nitrogen (million lbs/yr) % of cropland N reaches surface waters

16 Statewide N Sources to Surface Waters (average year) 16

17 Annual Nitrogen (million lbs) Point Sources Atmos. Into waters Feedlot Septic Urban NPS Forest Ag. Runoff Ag. Drainage Ag. Groundwater

18 Wet Year N Sources to Surface Waters 18

19 Sources & Pathways (statewide to streams) Pathways dominated by subsurface transport 73% average year 82% wet year Urban areas contribute some N 10% average year per acre contributions similar to cropland Municipal wastewater most of urban N Cropland is dominant source statewide 72% average year 83% wet year Varies greatly by crop, soils, drainage, mgmt & climate Other sources minor low N loads and/or concentrations

20 UMN/MPCA Source Assessment Checked against 1. Sparrow model 2. Load monitoring 3. Statistical analyses 4. HSPF model 5. Literature reviews 20

21 SPARROW Model Source Estimates Compared to UMN/MPCA Assessment 21

22 Load Monitoring compared to UMN/MPCA source assessment 22

23 Statistical Analyses Results consistent with UMN/MPCA source assessment Nitrate Concentration vs. % leaky row crop land Nitrite+Nitrate-N FWMC (mg/l) y = x R² = % 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% % of watershed in row crop over tile, sand, or shallow bedrock 23

24 HSPF Model Results Compared to UMN/MCPA Source Assessment Minnesota River Basin only HSPF UMN/MPCA subsurface pathways 89% 94% urban stormwater + feedlot runoff + forest 2.4% 1.5% N loads - wet years compared to average years 179% 170% 24

25 Reasonably well understood about N Statewide and Basin levels Sources Transport pathways Effects of precipitation High loading watersheds How much is transported downstream 25

26 Nitrogen Reduction Planning Tool Developed in 2012 by Univ. of MN W. Lazarus, D. Mulla, et al. For HUC8 watershed scale use, or statewide Estimates for watershed BMP adoption scenarios Costs N reductions in waters for Watersheds BMP options in spreadsheet N rates Fall to Spring N Sidedressing N Wetland Treatment Bioreactors Controlled drainage Cover crops Perennial vegetation on marginal lands & riparian

27 Planning Tool Shows Large scale BMP adoption needed for measurable reductions in water Source reductions Intercept and treat technologies Vegetative scavengers N reductions to streams with broad adoption of BMPs ~ 15-20% Statewide ~ 20-30% Heavily tiled watersheds ~ 10-15% Non-tiled watersheds Costs increase markedly after first 10-15% reduction 27

28 Rays of Hope Solutions? Some solutions have multiple benefits Room for progress with existing BMPs Research continues on possible game-changers i.e. economically viable perennial energy crops Collaboration increasing Minnesota Nutrient Reduction Strategy Iowa, Wisconsin, others working on this issue

29 Questions

30 Thank You Dave Wall

31 Trends in Nitrite plus Nitrate Concentrations in Selected Streams in Minnesota, Minnesota Water Resources Conference October 16-17, 2012 U.S. Department of the Interior U.S. Geological Survey St. Paul, MN Dave Lorenz, USGS, Mounds View, MN Dave Christopherson, MPCA, St. Paul, MN Gary Martin, USGS, Louisville, KY Dave Wall, MPCA, St. Paul, MN A cooperative project by the USGS and MPCA

32 Why Analyze Trends? 2 Clean Water Act Passed in 1972, the act established the goals of eliminating releases of high amounts of toxic substances into water, eliminating additional water pollution by 1985, and ensuring that surface waters would meet standards necessary for human sports and recreation by 1983.

33 How to Analyze Trends? Short-term, Monotonic Trends Trends Overall Seasonal S Concentration NOx concentration Season

34 How to Analyze Trends? Long-term, Dynamic Trends Common log residuals 4

35 How to Analyze Trends? Long-term, Dynamic Trends 5

36 What are the Shortterm Trends? Trends Up at.1 Up at.5 None at.5 Down at.5 Down at

37 What are the Long-term Trends? MI

38 Pomme de Terre Yellow Med. Redwood CottonWood 8

39 Yellow Med. Redwood Cottonwood Minn. Courtland 9

40 Cottonwood Minn. Courtland Watonwan Blue Earth 10

41 Minn. Courtland Watonwan Blue Earth Minn. Henderson 11

42 Blue Earth Minn. Henderson Minn. Jordan Minn. Airport 12

43 Summary Some trends are up, some are down Only fair agreement between the short-term trend results and the last few years of the long-term results Long-term results presented for Minn. R. only Final report looks at 54 long-term sites, year sites and year sites 13

44 QUESTIONS? 14

45 Central Sands Private Well Network 2011 Nitrate-N Sampling Results Kimberly Kaiser Minnesota Department of Agriculture Fertilizer Management Unit 2012

46 14 Counties make up the Central Sands Region The Central Sands Region is characterized by sandy outwash glacial plains that are highly susceptible to surface activities.

47 High value crops such as edible beans, corn and potatoes dominate the landscape. Intensely irrigated.

48 MDA Monitoring Network Wells MDA has been monitoring groundwater since In 2000, a statistically designed network was installed to sample the water table at the edge of fields. Since 2000, quarterly median results of this network have been over 10 mg/l. MDA Summary of Nitrate Nitrogen Data:

49 Phase 1. PROJECT GOALS Short term goal: Determine current nitrate concentrations in private wells throughout the Central Sands region. What are people drinking? Identify Areas of Concern. Phase 2. Long term goal: Determine long-term trends; whether nitrate concentrations are stable, increasing, or decreasing. Continue to assess Areas of Concern

50 This approach is modeled after a pilot project in Southeastern Minnesota: Volunteer Nitrate Monitoring Network Partners/cooperators: MDA PCA MDH Southeastern Minnesota Water Resources Board Downloads/SEMWRB%20Final%20Report%20V NMN% %20.pdf

51 In order to accomplish the goals of the first phase, MDA established a grant project with the Wadena county SWCD. MDA developed the design and the original parcel list. Wadena coordinated the survey work and sample analyses.

52 An unaligned randomly started grid was placed over the 14 counties. Grid nodes are approximately 2 miles apart.

53 Grid nodes that were in township with < 20% row crops, were clipped out. Municipalities and public land were also clipped out.

54 1. A 1.5 mile buffer was drawn around each grid. 2. The buffers were then placed over parcel data. Homesteaded with building values > $20K. Approximately 2300 buffers parcels were randomly selected from each buffer. 4. Each received an invitation letter and survey about their well.

55 1. Where did the water sample come from? 1 Sub-division 2 Lake Home 3 Country 4 Municipal (If municipal well, stop here and return form, you will not be included in the private well network.) 2. If the water sample came from the country, do you have livestock (more than 10 head of cattle, 30 head of hogs or an equivalent number of other livestock)? 1 Yes 0 No 3. If the sample came from the country, do you mix or store fertilizer (500 lb. or more) on the farm site? 1 Yes 0 No 4. Does farming take place on this property? 1 Yes 0 No 5. Does your well have a county well index number? Yes or No (found on your well casing) If yes, what is the County Well Index number? or don t know (found on your well casing) 6. Approximate age of your well? years years years 4 over 50 years 7. Approximate depth of your well? Feet feet feet 4 over 300 feet 8. Distance to an active or inactive feedlot? Feet feet feet 4 over 300 feet 9. Distance to a septic system? Feet feet feet 4 over 300 feet 10. Distance to an agricultural field? Feet feet feet 4 over 300 feet 11. Type of well construction? 1 Drilled 2 Sand point 3 Hand dug well 4 Flowing 5 Other 12. Is this well currently used for human consumption (Drinking or Cooking)? 1 Yes 0 No 13. Please check any water treatment you have other than a water softener. 0 None 1 Reverse Osmosis 2 Distillation 3 Filtering system 4 Other 14. When did you last have your well tested for nitrates, lead, hardness, bacteria, etc.? 1 Never tested 2 Within the past year 3 Within the last 3 years 4 Within the last 10 years 5 Greater than 10 years 6 Don t remember

56 Final Sample Status of the Well Survey performed by The Minnesota Center for Survey Research-U of M A total of 6605 surveys were sent out to parcel owners (46%) returned a completed survey of the 2989 were sent a water sample kit, 1167 were not. Which means that more than one well owner responded per buffer- good response!

57 1822 well owners were sent a sample kit that contained a bottle, sampling instructions, and a prepaid mailer to send the sample back to the lab well owners sent in their water sample.

58 2011 Private Well Network Nitrate-N Sampling Results 7% 5% Nitrate-N <3 mg/l Nitrate-N 3-10 mg/l Nitrate-N 10 mg/l 88% 1555 wells were sampled in the first phase.

59 Central Sands Private Well Network 2011 Nitrate-N Results Summary County Number of Samples Min Median Max % at or below 3 (mg/l) % between 3-10 (mg/l) % at or above 10 (mg/l) Becker 123 <.03 < % 5% 2% Benton 57 <.03 < % 12% 9% Cass 82 <.03 < % 4% 0% Crow Wing 66 <.03 < % 8% 0% Douglas 90 <.03 < % 6% 0% Hubbard 65 <.03 < % 8% 8% Kandiyohi 117 <.03 < % 3% 4% Morrison 124 <.03 < % 11% 11% Ottertail 320 <.03 < % 4% 5% Pope 93 <.03 < % 1% 5% Sherburne 42 <.03 < % 5% 5% Stearns 167 <.03 < % 13% 4% Todd 137 <.03 < % 5% 2% Wadena 72 < % 17% 8% Average 1,555 total samples < % 7% 5%

60 Nitrate concentrations vary greatly over short distances. Clusters of wells with high concentrations are observed.

61 Wells that are located in high water table sensitivity are significantly different than wells in the low and medium sensitivity combined. (Kruskal- Wallis non-parametric method)

62 Well Construction and Nitrate Concentrations Average %>10 Median Nitrate-N mg/l Percent > 10 mg/l 0 Hand Dug (30) Sandpoint (139) Drilled (1298) Other (90) 0 Well Construction Type

63 Well Depth and Nitrate-N Concentrations Average %>10 Median Nitrate-N mg/l Percent > 10 mg/l to to to 300 Over 300 DK 0 Depth in Feet

64 Well Age and Nitrate-N Concentrations Average %>10 Median Nitrate-N mg/l Percentant > 10 mg/l 0 # of Wells 0 to to to 50 > 50 DK Well Age in Years

65 First Phase Summary 1555 Well owners were the cornerstone of this project. Nitrate-N concentrations are lower in the private wells than in the MDA monitoring wells. Well construction, well depth, and well age are important factors affecting the quality of water in private wells.

66 Phase 2: A new joint powers agreement between MDA and Wadena SWCD was developed to establish a long-term network Wadena SWCD was responsible for: Sample kit preparation Sample kit mailing, sample tracking, and receiving Phone calls, coordinating with 13 other counties Sample analysis - the table top UVspectrophotometer is used to analyze samples in the long-term network.

67 Ultra-Violet Spectrophotometers allow rapid and accurate nitrate-nitrogen analysis The UV method requires no reagents or time for color development

68 Phase 2: Volunteers All well owners from the 1 st phase were invited to participate in the long-term network. MDA planned to continue this network for as many as 800 wells. Approximately 550 well owners were willing to continue the annual sampling.

69 Phase 2: Site Visits Each well in the second phase will be visited by a county well coordinator. A water planner or water technician from each county was trained to perform the well site visits. This was done in cooperation with the Minnesota Department of Health, Jim Lundy.

70 Phase 2: Site Visits Training Step 1: Get Organized. Collect all of the available information about the well. Step 2: Collect Information at the Well Site. Step 3: Collect Information About Potential Nitrate Sources. Step 4: Verify the Well Location.

71 Well Logs Provide: Well depth Casing diameter Well age Geologic material Grouted?

72 Step 3: Collect Information About Potential Nitrate Sources

73 Phase 2: Data Transfer/Analysis Each county will provide MDA the information obtained from the well site visits. The information from the well site visits will be analyzed.

74 Central Sands Private Well Network 2012 Nitrate-N Results 8% 3% Nitrate-N <3 mg/l Nitrate-N 3-10 mg/l Nitrate-N 10 mg/l 89% Approximately 500 well owners have returned samples for 2012

75

76 What s Next??? Continue monitoring with the participating volunteers. Aquifer designation using well log information into database Find ways to keep the volunteers involved and interested. Prioritizing areas of concern, targeting townships for Nitrate-N sampling

77 nd/gwdwprotection/characterizingnitrates.aspx Contact info: Kimberly Kaiser

78 Questions or Comments?