1 / 42

Developing Nutrient Criteria – Divide and Conquer! Dan Obrecht, MU Limnology

Developing Nutrient Criteria – Divide and Conquer! Dan Obrecht, MU Limnology. How do you set nutrient criteria for ~ 400 lakes that vary in:. Size (area and volume) Watershed (size and impacts) Hydrology Use. By dividing them into manageable groups. Start here. ?. Group A. ?. Group B.

Faraday
Download Presentation

Developing Nutrient Criteria – Divide and Conquer! Dan Obrecht, MU Limnology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Developing Nutrient Criteria – Divide and Conquer! Dan Obrecht, MU Limnology

  2. How do you set nutrient criteria for ~ 400 lakes that vary in: • Size (area and volume) • Watershed (size and impacts) • Hydrology • Use

  3. By dividing them into manageable groups.

  4. Start here ? Group A ? Group B Group C ? Group D or Group E or Group F ?

  5. Lake/Reservoir data sets • 147 waterbodies that MU has monitored for at least four years • 457 waterbodies listed as classified

  6. Set criteria knowing that these lakes are naturally nutrient rich due to their shallow depth and location in the floodplain. Also note that watershed is difficult to define. Is it a Big River remnant lake? yes no

  7. Big River lakes account for 12 MU and 15-25 classified lakes Water Quality Data for the 12 MU Lakes median range Total Phosphorus (μg/L) 186 64 – 395 Total Nitrogen (μg/L) 1,340 648 – 3,291 Chlorophyll (μg/L) 51 23 - 223 Inorg. Susp. Solids (mg/L) 23 3 - 74 Secchi (meters) 0.29 0.15 - 0.73

  8. Is reservoir greater than 2,000 acres? Set criteria on an individual basis due to the differences among the reservoirs and their complex nature. Set criteria for dam site as well as the individual arms? yes no

  9. Large Reservoirs account for 12 MU and 12 classified lakes (though not the same 12!)

  10. MU list Truman Classified list Truman Lake Ozarks Lake Ozarks Table Rock Table Rock Stockton Stockton Mark Twain Mark Twain Pomme de Terre Pomme de Terre Wappapello Wappapello Smithville Smithville Thomas Hill Thomas Hill Long Branch Long Branch Taneycomo Bull Shoals Clearwater Silver Lake - Levee 3 If surface area is lowered to 1,500 acres: Montrose Taneycomo, Clearwater and Duck Creek

  11. Large Reservoirs Water Quality Data for the 12 MU Lakes median range Total Phosphorus (μg/L) 30 10 – 58 Total Nitrogen (μg/L) 638 235 – 1,223 Chlorophyll (μg/L) 12 3 - 18 Inorg. Susp. Solids (mg/L) 3 <1 - 9 Secchi (meters) 1.4 0.5 – 3.2

  12. Set criteria realizing that these reservoirs probably have short residence times and possibly internal loading issues. Is reservoir < 20 acres in size? yes no

  13. Small lakes account for 8 MU and 118 classified lakes Water Quality Data for the 8 MU Lakes median range Total Phosphorus (μg/L) 24 14 – 77 Total Nitrogen (μg/L) 590 427 – 1,313 Chlorophyll (μg/L) 12 3 - 18 Inorg. Susp. Solids (mg/L) 2 1 - 8 Secchi (meters) 1.4 0.5 - 1.9 Six of the eight MU reservoirs are located in Ozark Region. Mean % forest for all eight is 55%.

  14. Does reservoir have average depth of < 1 meter? Set criteria realizing that these reservoirs probably have short residence times and possibly internal loading issues. yes no

  15. Shallow lakes account for 0 MU and ? classified lakes

  16. Does reservoir have a municipal point source in it’s watershed? Worth noting these reservoirs due to TMDL considerations associated with the point source. yes no

  17. Reservoirs with municipal point sources and permitted point source volume (MGD) Table Rock – 47.472 Smithville – 0.571 Truman – 15.717 Killarney - 0.467 Mark Twain – 13.550 Long Branch – 0.359 Stockton – 8.312 Clearwater – 0.290 Lake Ozarks – 6.231 Lake St. Louis – 0.272 Wappapello – 4.553 Thomas Hill – 0.139 Taneycomo – 3.625 Springfield – 0.112 Pomme de Terre – 1.788 Rocky Fork – 0.009

  18. Lakes with point sources account for 4 MU and ? classified lakes Water Quality Data for the 4 MU Lakes median range Total Phosphorus (μg/L) 59 21 – 63 Total Nitrogen (μg/L) 749 538 – 952 Chlorophyll (μg/L) 14 6 - 26 Inorg. Susp. Solids (mg/L) 4 2 - 10 Secchi (meters) 0.8 0.5 - 1.8

  19. Does reservoir have an urban watershed (>50%)? These reservoirs will have different nonpoint source impacts than others. yes no

  20. Urban lakes account for 9 MU and ? classified lakes Water Quality Data for the 9 MU Lakes median range Total Phosphorus (μg/L) 32 16 - 55 Total Nitrogen (μg/L) 672 383 - 916 Chlorophyll (μg/L) 16 4 - 21 Inorg. Susp. Solids (mg/L) 4 2 - 9 Secchi (meters) 1.1 0.5 - 2.0

  21. Urban lakes sampled by MU Longview Waukomis Weatherby Tapawingo Prairie Lee Winnebago Raintree Jacomo Blue Springs

  22. That leaves… 102 MU reservoirs and ~200 – 300 classified lakes

  23. Regional breakdown of MU reservoirs Ozarks (n-37) Plains (n-65) median (range) median (range) TP μg/L 20 (6 - 64) 53 (14 - 182) TN μg/L 480 (200 - 1060) 900 (420 - 2330) CHL μg/L 5 (1 - 36) 16 (3 - 56) ISS mg/L 2 (<1 - 4) 5 (<1 - 47) Secchi meters 1.6 (0.7 - 4.1) 0.7 (0.2 - 2.6)

  24. Other ways of dividing the reservoirs into groups

  25. Drinking Water Reservoirs MU has monitored 33 in Plains region and 5 in Ozarks median range Total Phosphorus (μg/L) 49 11 - 182 Total Nitrogen (μg/L) 810 360 - 2330 Chlorophyll (μg/L) 14 4 - 41 Inorg. Susp. Solids (mg/L) 4 <1.0 - 15 Secchi (meters) 0.8 0.4 - 2.8

  26. Drinking water by regionmedian (range) Ozarks (n=5) Plains (n=33) TP μg/L 28 (11 - 57) 50 (21 – 182) TN μg/L 483 (360 - 657) 926 (430 – 2330) CHL μg/L 6.2 (4 – 24) 14.4 (4 – 41) ISS mg/L 1.6 (0.9 – 4.2) 4.7 (1.6 – 15) Secchi meters 1.2 (0.7 – 2.8) 0.7 (0.4 – 1.8)

  27. “Protected Reservoirs” based on 25th percentiles

  28. “Protected reservoirs” for whole state * Denotes the reservoirs in the Plains region. List based on TP <22 μg/L

  29. Plains Region “Protected Reservoirs” based on 25 percentile CHL 11.5 μg/L TP 32 μg/L TN 672 μg/L

  30. Ozark Region “Protected Reservoirs” based on 25 percentile CHL 3.0 μg/L TP 12 μg/L TN 332 μg/L

  31. Hydrology and Phosphorus

  32. Multiple Regression Plains Region Log TP = 1.709 + 0.417*log flushing index R2 = 0.51 Log TP = 1.845 + 0.361*log flushing index – 0.038*mean depth R2 = 0.56 Lake Volume, Lake Area and Watershed Area - NS

  33. 25th percentile Phosphorus values at different Flushing Indexes for the Plains Region Flushing Index Residence Time Target TP (times per year) (months) (μg/L) 4 3 85 2 6 61 1 12 44 0.66 18 36 0.50 24 31 0.40 30 28 0.33 36 26

  34. Multiple Regression Ozarks Region log TP = 1.46 – 0.032*mean depth R2 = 0.15 Flushing Index, Lake Volume, Lake Area and Watershed Area - NS

  35. 25th percentile Phosphorus values at different Flushing Indexes for the Ozark Region Flushing Index Residence Time Target TP (times per year) (months) (μg/L) 4 3 21 2 6 19 1 12 17 0.66 18 15 0.50 24 15 0.40 30 14 0.33 36 14

  36. Questions?

More Related