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The Study

Identify and Quantify. It was determined that additional expertise was need to complete a formal lake study in order to help determine if the lake should be dredged and if so, for the process to conform to agencies' permitting requirements.

Funding the Study. Various sources for funding the study were contacted, and presentations were made where needed. The study was funded by Sherburne County, Sherburne County Soil and Water Conservation District, the Elk River Lions, the Elk River American Legion, LOIA and the City of Elk River.

Study cover [15K]We developed a Request for Proposal (RFP) for the study which included sedimentation and water quality issues, and sent it out to several companies to bid on. We selected Wenck Associates of Maple Plain, MN in 1996.

At the same time, the SWCD had committed to studying the watershed with a $60,000 grant from the DNR. Interns would help during the summer in surveying the Elk River Watershed (not just Lake Orono), noting erosion problems and doing some water sampling.

The study was conducted for a year to gather enough substantative data. Our Association helped with the study by providing man and boat power in taking water samples from the lake, monitoring storm events which helped in determining the rate and quality of runoff, and digitizing a 1970 DNR map of our lake with depth indicators to compare with a more recent 1996 DNR survey.

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Results of the Study

The study was completed in October of 1997. Following is a synopsis of the study and the Task Force's recommendations. For a complete copy of the study and the Task Force recommendation, please email LOIA at email: info@lakeorono.org.

  • Sedimentation
    Basically, since the lake is a dammed up portion of the river, it is trying to become a river again. Findings indicated that the farthest west lobe of the lake where the river enters is virtually unnavigable, and that the lobe just east of Boy Scout Island is also filling in, along with isolated spots throughout the lake. It is estimated that this second lobe will be mostly filled in in about 30 years; excavated, it would last perhaps an additional 50.

    Suspended sediment. More suspended sediment was leaving the lake than entering it. City staff felt suspended sediment is not a major issue because the lake is not large enough to settle it out; it passes through instead.

    Bedload. Bedload is the heavier material transported by the Elk River and deposited in the lake. The study estimated that the average rate of bedload being deposited in the lake is 3,000 cubic yards per year, which is not an unusually high rate, but sources of erosion upstream should be eliminated as much as feasible.

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  • Water Quality
    Contaminates. Sediment samples were analyzed for heavy metals, pesticides, PCBs, semi-volatile organic compounds and other subtances. No significant levels were found. This is signifcant both as a public health issue and as far as disposing of material that is dredged from the lake.

    Phosphorous. Levels in Lake Orono are high for a lake, but normal for a river, particularly in the Central Hardwoods Forest region. Leaves falling into the lake and river already provide significant levels of phosphorous.

    Phosphorous is a nutrient that feeds algae, and results in the water turning green. Reducing the man made sources of phosphorous will help reduce the frequency and intensity of algae blooms, but will not eliminate them.

    Fecal Coliform. Tests on the lake occasionally indicated high levels of fecal coliform. Using an additional test, it was determined that the organisms were from animals, not humans. Fecal coliform of animal origin is not considered as much of a health threat as those from human origin. This type of bacteria does not last long and will soon die, therefore it was hypothesized that any sources were no more than a day upstream or in the lake area. One particular source was fingerpointed and eliminated (a mulch used on exposed ground was previously used as animal bedding). One possible source may be the high geese population surrounding the lake (one goose produces approx. 3 lbs. of manure a day). It was determined that the City will regularly test the water and take any appropriate action.

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Continued


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