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Studies: Gilfillan Lake

• Aquatic Plant and Bathymetry Survey 2023
• SLMP Appendix A Wenck Memo
• SLMP Appendix B Gilfillan Lake Groundwater Influence
• SLMP Appendix C 1992 CRA Report on Groundwater
• SLMP Appendix D Lake Sediment Results
• SLMP Appendix E RCD Response for Request for District Assistance
• SLMP Appendix F Highlight of Small Waters Appropriations Permit

Gilfillan Lake is located in the City of North Oaks and is surrounded by light residential land cover. Historically, the lake was converted from a wetland to an open surface water lake around the time that residential development began in the late 1940s and early 1950s. The lake level began to drop between 2009 and 2010, and the lake owners around the lake pursued the path towards augmenting water from Pleasant Lake into Gilfillan. Permission was granted by the DNR and other agencies to go ahead with the augmentation. In 2011 and 2012 water was pumped to increase the lake level to its ordinary high water level (OHWL). The pumps are run at the beginning of every season for maintenance purposes, but not since 2012 have they been run to maintain the lake's water level. The project was funded by the citizens living around the lake.

Gilfillan Lake was added to the MPCA's List of Impaired Waters in 2010 as impaired for recreational use due to high nutrient/eutrophication levels in the lake, as documented by VLAWMO through the monitoring program. After the lake was augmented, nutrient levels plummeted below state standards from more phosphorus levels than 3 times the state standard in 2010 down to just below the state standard in 2013. 2014 monitoring data still shows Gilfillan below state standard, but 2015 shows nutrient levels being just under state standards. There was a hope for removing Gilfillan off of the Impaired Waters List after augmentation, though it may be that after a few years of "settling", nutrient levels may be stabilizing again above state standard levels. Lake monitoring performed twice monthly during every monitoring season will continue to track the lake's nutrient levels.