Rains, gate failure disrupt marsh management

Aaron Brault • Director, County Planning & Conservation Dept.

Like most ecosystems, wetlands are dynamic and need constant change to thrive.

The Broughton Sheboygan Marsh Strategic Management Plan of 2013 outlines and directs the use of draw downs every five years as a management tool for Sheboygan Marsh.

On a controlled and managed wetland restoration, such as at the Sheboygan Marsh, draw downs mimic natural drought cycles which occur on natural wetland ecosystems. The benefits of using a drawdown in this managed wetland are:

• Helps to anchor and stabilize cattail mats, and allows the establishment of less aggressive, more beneficial aquatic plants.

• Increases the number of different species of plants and animals in the marsh (diversity).

• An increase in aquatic plants helps to reduce suspended sediments, which helps to improve water clarity and quality.

• Increases water column depth by exposing and compacting submergent vegetation and bottom sediments and by allowing the oxidation of those organic materials.

• Improves wildlife habitat for several years for waterfowl, shorebirds, muskrats and other wetland wildlife.

• Increases related recreational uses (waterfowl hunting, fishing, and wildlife viewing) for 1-to-5 years following the drawdown.

• Reduces tax dollars required to remove floating cattail mats that block the dam, bypass, and boat launch.

Years following a drawdown typically have very little to no cattail issues.

In 2017, attempts were made to drawdown the Sheboygan Marsh per the management plan. Due to the very wet weather throughout spring and summer last year and the timing of those rain events, the 2017 drawdown was never completed. The bypass tube simply could not pass enough water to keep up.

The 2018 drawdown was expected to start in early spring.

However, after 50 years of service the dam bypass gate control structure failed in mid-May and was stuck in the down position until crews were finally able to remove it in early July.

The Sheboygan Marsh is now being drawn down as there is no longer a gate to control the water flow.

An engineering firm was recently chosen to begin the design and permitting work for a new bypass gate control structure. The objective is to have the engineering and permitting completed so a new structure can be installed soon after the new year.

It is typically the goal to start filling the Marsh back up in late September by closing the bypass gate.

Unfortunately, this year, this will likely not happen due to the bypass gate failure though we are exploring options for a temporary solution.

A list of frequently asked questions about draw downs can be found on the Sheboygan County Planning& Conservation Department’s website.

For more information, please contact the Sheboygan County Planning & Conservation Department at 920- 459-3060

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