Rehabilitation and Continuing Management of an Urban Lake Shoreline in Southeastern Minnesota, USA

Abstract

Lake Winona is a 129-hectare urban lake which occupies part of an old side channel of the Mississippi River and has been modified significantly over the past 125 years. The entire shoreline (>8 km) is publicly owned, with current shorelines created mostly during two periods of lake dredging and filling of fringe wetlands 70 and 110 years ago, respectively. Since then, some sections were allowed to revegetate naturally with trees and shrubs, some were armored with riprap, and others have been maintained mostly as turfgrass parklands. Shoreline vegetation assessments and tree stand surveys were completed prior to beginning targeted shoreline rehabilitation in 2017. These rehabilitation activities (encompassing the majority of shoreline) include the following: (1) repeated removal and chemical treatment of woody invasive shrubs/trees (primarily common buckthorn Rhamnus cathartica and nonnative bush honeysuckles Lonicera spp.) by contractors and volunteers; (2) chemical spraying and hand pulling of nonnative invasive ornamental grasses (Miscanthus spp.) and forbs (Japanese hops Humulus japonica; leafy spurge Euphorbia esula) annually or as needed; (3) killing of turfgrass and overseeding with native prairie species; (4) shrub and sapling plantings and overseeding with native species in both wooded and turfgrass sections; (5) installation of wave barriers (using cut woody invasives) and planting of emergent aquatic macrophytes; (6) prescribed burns of prairie plantings; (7) establishment of fixed photo reference points to document changes; and (8) altered park mowing practices to maintain a shoreline buffer of vegetation. These ongoing management activities aim to replace more turfgrass with native prairie, plant more shrubs and trees on shorelines, suppress nonnative invasives, and encourage the development of aquatic macrophyte beds to reduce, or eliminate shoreline erosion. Future management activities will continue to emphasize invasive species control, turfgrass conversion to native vegetation, and shoreline erosion reduction.