Lake Nokomis Weir Renovation

Overview

In 2012, the Minnehaha Creek Watershed District (MCWD) and the Minneapolis Park and Recreation Board (MPRB) renovated the existing weir at Lake Nokomis. The renovation changed the weir from an inflatable to an adjustable fixed design, a more rigorous and reliable structure that protects the water quality of Lake Nokomis and prevents the introduction of AIS to the lake as much as possible. As the lake’s only outlet, the weir can be adjusted to release water if lake levels get too high.

MCWD originally constructed the weir, a dam-like structure that holds back water, in 2000 to keep polluted water from Minnehaha Creek out of Lake Nokomis. The inflatable weir was intended to inflate automatically and block flow from Minnehaha Creek to Lake Nokomis if an abrupt rise in the creek level was detected by sensors. The inflated weir was supposed to deflate after the creek level dissipated, however, over time the inflatable weir had become less reliable and created a need for staff to manually operate it. After a decade of use, components of the inflatable weir needed repair and replacement. Additionally, zebra mussels, an aquatic invasive species (AIS), were found in both Lake Minnetonka and Minnehaha Creek. To improve the weir’s function and keep zebra mussels out of the lake, MCWD and MPRB conducted the renovation.