City Finalizing New Plan to Manage Water Weeds

This map outlines the 121 acres for the City of Sturgeon Bay to mechanically harvest aquatic plants in the bay. Submitted.

The City of Sturgeon Bay is finalizing a new five-year aquatic plant management plan after the city’s Aquatic Plant Management Plan Revision Ad Hoc Committee met twice last month with Tim Hoyman, lead aquatic ecologist from Onterra, the firm hired by the city to update the plan.

“The goal of putting a plan together like this is getting a five-year harvesting permit,” Hoyman said. 

The Bay of Sturgeon Bay is about 4,000 acres, but the project area is only a quarter of that at a little over 1,000 acres, Hoyman said.

“The other part is that we really only manage a small percentage of the project area,” he said.

He said several native and non-native species of aquatic plants saw “statistically significant changes,” between the 2016 and 2023 surveys of plants in the bay, which are likely natural cycles brought on by changing water levels and interactions among species.

With 44 different types of aquatic plants in the bay, and only five of those non-native, Hoyman said Sturgeon Bay has a nuisance plant problem rather than an aquatic invasive species (AIS) problem.

Though an invasive species known as curly-leaf pondweed “increased significantly” compared to 2016, and likely brought on early-season problems navigating in the bay where it was present, Hoyman said the invasive plant dies back in early- to mid-July, so those issues do not last throughout the summer.

The city has been managing the growth of aquatic plants in the bay by harvesting them in designated cutting areas, as well as spraying herbicides using a permit from the Wisconsin Department of Natural Resources (DNR).

Management Strategy

In the mechanical harvesting areas, the draft of the new management plan calls for cutting them in the designated areas to half the water depth or 4 feet, whichever is shallower.

The plan adds two areas for mechanical harvesting – the Lama Wamah lagoon north of Sunset Park, where a 20-foot-wide access lane would be cut up to twice each summer, and at Bullhead Point on the west side, where a 10-foot-wide access lane for kayaks would be maintained as needed throughout the summer.

Harvesting crews will also pick up aquatic plants harvested by business and private pier owners, and in cases where residents place aquatic plants at the end of their docks, the draft of the new management plan states the pier owners should contact the Municipal Services office to ensure crews are notified of the piles to pick up.

The city also wants to be able to apply up to two herbicide treatments to aquatic plants in marina areas, compared to one having been previously allowed by the DNR. 

The second treatment, if required, would follow the same pretreatment inspection procedure as the first, such as whether the area to be treated poses a current or anticipated nuisance with aquatic plants.

The treatments would occur in mid-June to early July and late-July to mid-August, if required.

Next Steps

In addition to the draft of the city’s aquatic management plan being provided to the DNR for review, Hoyman said it will also be posted on the city’s website for a 21-day review, after which time applicable comments from the public and the DNR will be integrated before finalization.

District 1 Alderperson Helen Bacon, who chairs the city’s Joint Parks and Recreation Committee and Board, said the committee/board will subsequently consider the management plan before recommending it for approval by the Common Council.