Ice-Out officially called for Lake Winnebago

Ice-Out officially called for Lake Winnebago – April 6, 2022

Ice out on Lake Winnebago was officially called by the Army Corps of Engineers on April 6, 2022 as determined by MODIS satellite imagery. Ice out (aka ice off) is when ALL ice is gone from the lake surface as observed by satellite. Ice out triggers spring refill of Lake Winnebago.

MODIS Satellite Image from 4/6/2022

Lake Winnebago Ice out dates since 2006

The Army Corps of Engineers – Chicago District manages water levels in Lake Winnebago by regulating outflow at the dams in Menasha and Neenah under the Federal Marshall Order of 1886. The Marshall Order is intended for flood risk management.

Lake level for Lake Winnebago is an average of readings from four gages located around the lake and is in reference to the Oshkosh Datum.

The Marshall Order defines the limits of regulation for Lake Winnebago:

May 1st to October 1st (navigation season):
- High end of limit: 3.45 ft.
- Low end of limit: 1.68 ft.
October 2nd to April 30th:
- High end of limit: 3.45 ft.
- Low end of limit: 0.18 ft.

As of 2021/2022 regulation strategy, fall drawdown is scheduled to begin between Sept 1 and Oct 1 at the discretion of the Army Corps through an adaptive decision making process. The total seasonal water elevation change is typically about 1.8 ft in a given year.

The Army Corps attempts to meet the needs of several different stakeholder interests within their regulation limits.

The Army Corps draws down Lake Winnebago every winter to reduce the risk of damage caused by ice shoves, protect shoreline properties, and provide enough space within the lake to hold excess water that flows into Lake Winnebago each spring (snow melt and rain storm runoff from the 5,900 square mile watershed). The winter drawdown target operating band for Lake Winnebago this year was 1.2 ft to 1.3 ft.