Washtenaw County presents beaver-management plan to Ann Arbor parks panel

Harry Sheehan, deputy water-resources commissioner for Washtenaw County, told the Ann Arbor Parks Advisory Commission that beaver populations have rebounded across southeast Michigan and that the county has finalized a beaver-management plan focused on county drains. "They're here to stay. The question is, can we coexist?" Sheehan said during a June meeting held online.

Sheehan said the plan applies only to county drains—special-assessment drainage districts—and will not cover rivers, non-drain tributaries or county parks. He described a three-tiered site framework that starts all county drains in a "red" category and allows site-by-site movement to "yellow" or "green" where coexistence is appropriate. The approach aims to balance ecological benefits (including improved water quality, sediment settling and increased biodiversity) against property and infrastructure risks such as culvert blockages and tree loss.

To reduce conflicts, the plan lists three primary tools: a perforated pipe and protective cage (sometimes called a "beaver deceiver" or pond leveler) to manage pond height without drawing beavers' attention; semi-circular culvert fences to preserve flow capacity; and livestock-style tree fencing to protect individual trees. Sheehan said the county will pilot a pond-leveler at Nelson Park and anticipates installing coexistence measures at select city sites such as Alton Park.

Sheehan emphasized legal constraints. He said state law preempts local control over trapping and translocation, and referenced Act 222 as a statutory consideration that affects liability when blocked drains cause private-property damage. "We don't typically own the property that county drains are on," Sheehan said, noting the plan is designed for drains managed through easements and special-assessment districts.

Remy, who introduced the presentation and said the city's water-quality manager Jen Lawson will work with the county, said the county's plan will inform a separate city-specific beaver-management approach for water bodies not covered by county drains. The plan is finalized and undergoing an ADA compliance review; Sheehan said it should be posted on the county website within days to a week and will be treated as an adaptive management document.

The commission asked several jurisdictional and implementation questions. Sheehan responded that the county's jurisdiction is limited to county drains such as Traver Creek and parts of Miller and Fleming creeks within Ann Arbor, while rivers and non-drain tributaries remain outside the plan's scope.

Next steps: the county will post the finalized plan, pilot selected engineering fixes and work with city staff on a city-specific plan for areas the county does not cover.