Alternative 1: Optimize Storage in Larsen Lake Complex

Alternative 1 would modify the surrounding drainage courses and/or wetland areas to provide additional flood storage. This could be accomplished through a stream and wetland restoration alternative that would focus on removing non-native vegetation and realigning the existing drainage channels providing more natural meandering through the wetland areas to better engage them hydraulically during storm events. Woody material could be installed or provide grade controls to plug channels and create overland flow. This alternative would provide additional flood storage in the wetland complex around Larsen Lake and/or the wetlands on the west side of 148th Avenue Southeast. Additionally, one of the three existing fish barrier culverts would be replaced with a fish-passable culvert on the north end of 148th Avenue Southeast.

Construction impacts

Alternative 1 would benefit from minimal construction impacts to 148th Avenue Southeast since most work would occur in the Larsen Lake complex, also known as Lake Hills Greenbelt. A portion of 148th Avenue Southeast would need to be raised at the proposed culvert crossing, which would impact traffic during installation.

Potential results

Alternative 1 would provide minimal relief from flooding since 148th Avenue Southeast is continuing to settle. Only so much improvement to flood storage can be created in the Larsen Lake complex. In addition to not being a feasible long-term solution to chronic flooding, this alternative would have significant environmental impacts and require a more extensive permitting process.