Halsted Bay Alum Treatment Facility

Overview

The Minnehaha Creek Watershed District (MCWD) is exploring the opportunity to construct a water treatment facility on Halsted Bay of Lake Minnetonka. The treatment facility would pump water from Six Mile Creek, treat it with aluminum sulfate (alum), and discharge treated water into the creek before it enters Halsted Bay. Upon completion, the facility would reduce Halsted Bay’s phosphorus and nutrient load by an estimated 1,620 pounds per year. Additional project benefits include increased water clarity, the reemergence of aquatic habitat, and improved recreational value for Halsted Bay and Six Mile Creek.

Located at the western edge of Lake Minnetonka, Halsted Bay is polluted with high levels of dissolved phosphorus from upstream runoff and groundwater. Initial assessments of Halsted Bay identified that half of the pollution to Halsted Bay comes from Six Mile Creek and the Six Mile Marsh wetland. To meet state water quality standards in Halsted Bay, MCWD and its partners must address the water flowing from Six Mile Creek into Halsted Bay, and the internal nutrient loading of the bay itself.