8.1. SR 06-17-2019 - Laserfiche WebLink

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zone is the part of a lake where rooted aquatic plants can grow, though the maximum depth at which plants can grow depends on water clarity and so varies from lake to lake and even from year to year within the same lake. Lake Orono's maximum depth is 18 feet, and its current mean depth is 3.1 feet, although the historic mean depth is approximately 5 feet.' 3. The lake is a reservoir of the Elk River, created when a dam was constructed on the river in 1916. Water outlet level is maintained by the City of Elk River at 871 feet MSL. 4. Lake Orono is at the downstream end of the Elk River watershed. The immediate catchment has an area of approximately 5,943 acres, and the total upstream watershed has an area of approximately 388,456 acres, or 611 square miles. These yield land:lake ratios of approximately 9.8:1 for the direct catchment and 1,295:1 for the total watershed. 5. Agriculture covers almost half the area in the upstream watershed. Pasture and grazing land cover about 18% and row crops 27% of the watershed area. Forest, almost entirely deciduous, covers approximately 20%2. 6. Both basins of Lake Orono are considered to be impaired for mercury, water clarity, and nutrients. 7. The Elk River Watershed has multiple impairments in various lakes and along various stretches of the river. The water quality impairments on the Elk River all have a target Total Maximum Daily Load (TMDL) completion year of 2023, and consist of three bacteria (E. coli), two fish, and one aquatic macroinvertebrate bio -assessments. 8. In 2015, a TMDL was completed for Upper and Lower Lake Orono as part of the Mississippi River St. Cloud (MRSC) Watershed Restoration and Protection Strategy (WRAPS) and TMDL project (https://www.pca.state.mn.us/sites/default/files/wq-iw8-46e.pdf). The second cycle of the WRAPS process for the MRSC watershed began in May 2019. Through the WRAPS process, partners throughout the watershed will be working together to further evaluate the MRSC watershed and continue the ongoing efforts to restore and protect its surface water resources. This effort will include the review of existing and development of new restoration strategies within the Elk River Watershed (e.g., TMDL development and evaluation of implementation efforts for existing TMDLs). 9. Lake Orono is in the North Central Hardwoods Forest Ecoregion. The lake's water quality parameters are outside the means for this ecoregion, with water clarity lower and chlorophyll -a and total phosphorus higher than the means. 10. Lake Orono is considered to be eutrophic. The mean Trophic State Index (TSI) for Lake Orono is 61; values from 50 to 60 are considered to be mildly eutrophic and higher values are eutrophic. 11. Lake Orono is infested with curlyleaf pondweed (CLP), an aquatic invasive plant. In addition, the invasive emergent plants purple loosestrife (Lythrum salicaria) and yellow iris (Iris pseudacorus) grow along the lake's shoreline. 12. The City of Elk River maintains a concrete boat ramp in Lake Orono Park, on the western shore just south of US Hwy 10. A public fishing pier and public beach are located south of the boat ramp. 13. The proposed LID will include all properties with direct or deeded lake access. 14. The proposed method of the LID formation is by city resolution in response to citizen petition. 1,2 Lake Orono Lake Management Plan 2017-2020 DNR Advisory Report on Lake Orono Lake Improvement District Page 2