Prior Lake - Spring Lake Watershed District 2009 Water Quality ...

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Figure 7 – Red points indicate that dissolved oxygen readings had gone below the 5 mg/L standard for streams during the2009 synoptic monitoring study.Page 12 of 15
d. Specific Conductance (conductivity)Conductivity is a means of measuring the ability of water to conduct electricity (Our Lake,2010). Specifically, conductivity in water is affected by the presence of chloride, nitrate,sulfate, phosphate anions, sodium, magnesium, calcium, iron, and aluminum cations (EPA, Feb25, 2010). Higher conductivity values indicate that pollution may be a concern or it can also benaturally high depending on the geology of the soil and bedrock. Pure water has a theoreticalvalue of zero µs/cm. Some anthropogenic (human caused) sources of high conductivity mayinclude wastewater treatment plant effluent, road run‐off (road salt and automobile fluids),and agriculture run‐off (Murphy, 2010).Rain events can dilute the concentration of ions in a water body due to the naturally lowconductivity values of rainwater. However, if the watershed has many pollutants, like road saltand dirty streets, the conductivity may increase during a rain event. The MPCA reports that theconductivity values of a minimally impacted streams in the North Central Hardwood Forestrange from 40 – 840 µs/cm (McCollor and Heiskary 1993). No state water quality standard hasbeen determined for conductivity; however, the Natural Resources Research Institute (NRRI) atthe University of Minnesota Duluth created a relationship between chlorides and conductivity.The state water quality standard for chloride is 230 mg/L and they found that the chloridestandard is equivalent to a conductivity value of approximately 960 µs/cm(Lakesuperiorstreams, 2010).The lowest conductivity value observed was during synoptic monitoring with a value of 60.7µs/cm at site # 21 (the connection between Spring Lake and Upper Prior Lake) during a rainevent on October 6, 2009. The highest value was 2,030 µs/cm at site #33 during a rain event onApril 1, 2009. Refer to Figure 8 to see the range of maximum conductivity values observed in2009. Besides site #33, sites #2, #19, and #40 have the next highest values and are all located inthe Upper Watershed.Page 13 of 15
Page 1 and 2: Prior Lake ‐ Spring Lake Watershe
Page 3 and 4: I. IntroductionThe Prior Lake ‐ S
Page 5 and 6: The “Upper Watershed” consisted
Page 7 and 8: SSWCD staff worked collaboratively
Page 9: IV. Resultsa. IntroductionWater qua
Page 12 and 13: Figure 6 - 2009 Maximum Turbidity V
Page 16 and 17: Figure 8 - Red points indicate that
Page 18 and 19: Appendix 1 ‐ Synoptic Site Locati
Page 24 and 25: Appendix 2: Synoptic Data ‐ Sorte
Page 36 and 37: Site # & DateSampledAppendix 3: Syn
Page 48 and 49: Appendix 4 - Synoptic Graphs and Fi
Page 56 and 57: Appendix 5 ‐ Deployment Data 2009
Page 64 and 65:
Appendix 5 ‐ Deployment Data 2009
Page 66 and 67:
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