Lake Rebecca Water Quality Improvement Project

Lake Rebecca is a 256-acre degraded lake located in Lake Rebecca Park Reserve, Hennepin County.  Three Rivers Park District maintain a swimming beach, picnic areas, hike/bike trails, a boat launch, a boat rental facility, and two fishing piers in or adjacent to the lake.  In addition, Lake Rebecca is utilized by the DNR as a muskellunge brood stock lake for egg collection.  The lake is heavily used for pan fishing by minority populations, and for trophy muskellunge fishing.  In 2008, heavily used for pan fishing by minority populations, and for trophy muskellunge fishing.  In 2008, Lake Rebecca was listed as an impaired water body by the MN PCA because of excessive phosphorus levels and poor water clarity.  Seasonal algae blooms cause "pea-soup" green conditions in the lake, periodically resulting in fish mortality (over 30 and six bass died in 2007 from low dissolved oxygen levels) as dissolved oxygen level decline when algae populations die back.  Algae blooms are so severe that Three Rivers Park District must isolate the swimming facility from the main lake with beach curtain in order to provide swimming to park guests. 
Three Rivers Park District proposed to implement the water quality improvement program beginning in 2009.  The Park District plans to initiate the Curly leaf pondweed control program in 2009.  The alum treatment will occur after Curly leaf pondweed control in order to ensure successful application.  Shoreline stabilization practices will be implemented in 2010.  These activities will reduce phosphorus inflow to the lake and reduce internal recycling of phosphorus.  Reducing the in-lake phosphorus concentration will improve water clarity which, along with control of invasive plant species in the lake; concentration will improve water clarity which, along with control of invasive plant species in the lake will enhance the growth of native plant communities.  Improved water clarity, reduced algae growth and increase native plant growth will provide improved habitat for fish.  In particular, sight feeders such as muskies and bass will benefit from improved water clarity.  In addition, the fish will experience reduced mortality because of improved dissolved oxygen conditions in the lake. 
If this item if funded, the lake will experience improved clarity and replacement of invasive plants with native plant populations.  Because the Park District owns the entire lake shoreline, we can eliminate herbicide applications along the majority of shoreline and protect native plant populations.  In addition, the Park District can protect and enhance shoreline buffer areas along the lake shoreline.  The Park District has been collecting water quality data on Lake Rebecca for over 10 years.  Based on that data, water quality improvements are anticipated to occur within a year of initiation of the curly-leaf pondweed control program.  Growth response by native plants is expected to occur within 2 years.  Ultimate water quality goals will be achieved following the alum treatment.  The proposed management practices are proven technologies and have been used in other programs.  Therefore the project has a very high likelihood of success. 
Three River Park District works very closely with the local landowners, municipalities and watershed management organization to plan and implement water quality management programs.  The decision of these organizations can affect positively or negatively the expected impact of the proposed improvement program.  The Park District believes that the cooperative relationships it has developed with these organizations will lead to decisions that support the Park District efforts.  The Pioneer-Sarah Creek WMO had adopted a non-degrading policy to ensure long-term protection of water resources.