20230104 Environmental Board Packet Combined

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Shenandoah Improvements Feasibility Report City of Lino Lakes, MN WSB Project No. 018901-000 Page 4 To the west of this mound is an area containing tree species typical of a transition zone such as aspen (Populus tremuloides ). These trees are distressed and rotting. The west side of the turf area has large conifers that provide a screen from the adjacent residential home. Along the west edge of the project area are some existing box elder trees (Acer negundo ) and silver maple (Acer saccharinum ) and other small to medium sized diverse trees in good condition. 4.0 Identification of Issues The project area is sited at the intersection of a number of issues facing the City and RCWD. The proposed improvements can be leveraged to address multiple problems at once, the solutions provided by the project will balance the needs of these issues and provide a well -rounded benefit. 4.1 Lino Lakes Chain of Lakes TMDL Many of the lakes connected by Rice Creek in Lino Lakes fall under a TMDL for excess nutrients. This includes a 2010 TMDL for Rice Lake, the receiving water downstream of the project location. This TMDL estimates a 68 -80 percent reduction in TP loading to meet desired nutrient levels. This comes to an approximate reduction of over 9,300 pounds of TP. Much of this loading improvement may come from addressing upstream or internal phosphorous loading, however any reduction in TP is a net positive. As proposed, this project will result in a considerable reduction of TP loading to Rice Lake . 4.2 Invasive/Nuisance Vegetation The existing wetlands within the project area are domina ted by monotypic stands of cattails (likely invasive or hybrid) or stinging nettle with very low diversity and species richness. Along the ditch, invasive reed canary grass has prevented the growth of native vegetation. 4.3 Inefficient Use of Space The project space is currently very segmented, with the ditch, wetland, and park components separate from each other. There exists a great opportunity for a multifaceted approach at this site for water quality, ecological, floodplain, recreational, and educational be nefits. However, these benefits are either not being realized or only realized on an individual basis as -is. One major issue outlined by the City is a lack of connection between the well - developed trail system to the south and the trail system along Birch St to the north. Connecting these systems would also allow for better pedestrian access through the City and help to achieve its planning goals. 4.4 Floodplain As the downstream end of a stormwater system serving over 200 acres of drainage area, the site has h igh potential for flooding. As modeled in existing conditions, the 100 -year flood elevation is 892.15 feet . This high -water level approaches the lowest floor elevations of homes on Totem Trl. and Arrowhead Dr., putting these homes at risk of flooding. Prop osed project basins would lower this high -water level and decrease the risk of homes flooding.