At the FLOW Science Symposium, held on September 23, at the River Arts Center in Prairie du Sac, Bob Boucher, founding president of the Superior Bio-Conservancy (SBC) shared his healthcare plan for watersheds, including the Lower Wisconsin State Riverway. His talk was entitled ‘Rewilding with Beavers: Improving Hydrology, Biodiversity and Climate Resilience.’
“Beavers are the original ecosystem engineers and habitat builders, and when humans can find ways to work with them and co-exist, the co-benefits will be profound,” Boucher explained. “The hydrological structure of streams with beavers give us the ideal shape to store and retain water on the landscape, increased resilience in the face of weather and climate extremes, improved water quality, stable quantities of water, increased biodiversity, flood reduction and climate resilience.”
Boucher has spent his career working in northern Wisconsin, an area that has been devastated in recent years by extreme rainfall and flooding events. It is an area that Boucher describes as ‘Northwoods – the Headwaters of America and Life.’
The Superior Bio-Conservancy is an ambitious plan to protect and restore the biological integrity and hydrology of the Great Lakes Region and the Laurentian Forest Province throughout Minnesota, Wisconsin, and Michigan.
“The goal is to restore and support biodiversity, genetic exchange, ecosystem services and evolutionary processes for future generations,” Boucher explained. “This will be a health care plan for this Bio-Region of the Earth.”
A keystone species
Boucher said that beavers, a ‘keystone species’ in North America were once abundant on the landscape. With the coming of French fur traders in the 1600s, their populations rapidly dwindled in order to provide the furs for waterproof hats in Europe and the colonies in North America. Prior to settlement (pre-1600) the Western Great lakes landscape had one of the highest beaver population densities in North America, averaging 20 to 30 beavers per square mile.
A keystone species is a species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically.
“Beavers were locally extinct in the Milwaukee River watershed by 1730,” Boucher explained. “All rivers in Wisconsin in pre-settlement times had a beaver pond structure.”
According to Boucher, beavers, when included in a natural watershed and landscape management plan, retain eight times as much volume of water as in watersheds without them. This results in making the watersheds flood resistant. They also filter and cool the groundwater entering the system, producing increased stream health, complexity and biological productivity.
“Essentially, beaver ponds function as sewerage treatment plants and storm detention ponds,” Boucher said. “Beavers create conditions for the abundance of flora and fauna, and natural predators create a counter pressure and help to regulate the populations. Home territories of predators focus on connected routes between beaver wetland complexes.”
Co-benefits
According to Boucher, including beavers in a watershed increases the amount of water retained on the landscape. This provides numerous ecological benefits, and supports the goals of ‘biological integrity’ in the Clean Water Act by:
• creating habitat and shelter for fish, plants and organisms
• reduction of pollutants, especially nitrates
• cleaner water through filtration and recharging groundwater
• stabilizes water temperature to be cooler in the summer and warmer in the winter.
“Beaver wetland ponds are keystone habitats to waterfowl, and all bird populations, including ducks, geese, swans, cranes, herons, bitterns, egrets, and more,” Boucher pointed out. “They also create connected habitats that facilitate species migration, which is crucial given the plummet in bird populations in recent years.”
Beaver wetland ponds also, by retaining more water on the landscape, can serve as firebreaks and a refuge for species during a wildfire, according to Boucher.
Perhaps the most significant benefit of co-existing with beavers for humans is the ability of their ponds to support storm water storage. With the increasingly large and intense rainfall events seen in recent years, beaver ponds serve as natural storm water retention structures, similar to the dams built by humans. These structures, like dams, store the runoff and release it slowly.
“Beavers reconnect streams to their floodplains, allowing storm water runoff to spread out into the floodplain, slow down, and become less destructive,” Boucher pointed out. “In the process of this storm water storage, beaver ponds raise the water table, and refill groundwater aquifers.”
Milwaukee study
Boucher, who grew up in the Milwaukee area, was the founder of the Milwaukee Riverkeeper, a science-based advocacy organization working for swimmable and fishable rivers throughout the Milwaukee River basin.
In 2019/2020 Boucher worked with the Milwaukee Metropolitan Sewage District (MMSD) and UW-Milwaukee on a study to model the Milwaukee River watershed. Their goal was to measure the potential flood mitigation benefits of beaver-created wetlands to restore the natural hydrology of the basin, and to reduce flooding during high water events.
The study modeled the hydrology effects of placing beaver dams at 52 locations within the watershed. The model included storm events of various lengths of time, from six to 24 hours, and rain events equal to 5, 10, 25 and 100-year storms. The dams had three different heights in the model, at a half-meter, a meter, and one-and-one-half meters.
“In all cases, streams with beaver dams showed lower levels of initial runoff, and lower levels of release into watersheds following a storm event,” Boucher said. “As a result of our modelling exercise, we determined that with beavers used for flood mitigation, 500 homes would no longer be in the floodplain.”
Boucher said that the study demonstrated that the value of ecosystem services provided by beaver ponds in the watershed to MMSD would $3,346,000,000 in a full storage scenario. The system, as modeled at full storage capacity, would store 1.7 billion gallons of water, and at half storage capacity, 548 million gallons of water would be kept on the landscape and not released as storm water runoff.
“This would mean that 961 bridges and 1,027 culverts in the watershed were protected,” Boucher explained. “This would help to extend the lifespan of infrastructure and avoid costly repairs and replacements.”
Wisconsin out of step
Boucher pointed out that the State of Wisconsin is completely out of step with most states in terms of beaver management. He said that from 2000-2021, there had been 37,205 beavers killed in the state. He said this had ‘accidentally’ resulted in the killing of more than 2,200 otters.
“Wisconsin DNR sees beavers as threatening trout streams and creating nuisance flooding,” Boucher said. “On June 22, 2023, the Superior Bio-Conservancy filed a lawsuit against the USDA for killing 28,141 beavers, 1,091 river otters and destroying 14,796 beaver dams in 10 years, with all of the activity funded by the Wisconsin DNR. In 2022 alone, these activities hit a record high by killing 3,492 beavers – a figure more then three times the number anticipated in the 2013 environmental assessment.”
According to Boucher, the lawsuit alleges that as a result of this activity, WDNR and USDA Animal and Plant Health Inspection Service (APHIS) have destroyed wetlands, weakened flood resiliency and hampered biodiversity in the State of Wisconsin. The funds used for this ‘Beaver Elimination Program’ total millions of dollars, including revenue from timber sales from Wisconsin’s national forests.
According to WDNR, 32 percent of the state’s listed species are wetland dependent, and the state has already lost 47 percent of its original 10 million acres of wetlands. Thus, Boucher explained, beaver and beaver dam elimination further devastates and destroys the precious remaining damaged wetlands.
“After the 2013 assessment, APHIS failed to carry out the requirement to conduct annual reports on the beaver elimination program until 2020, when the six years prior were reviewed. The conclusion was that a revision to the program was needed because the amount of beavers killed was triple the amount targeted,” Boucher said. “And WNDR is no better, not following any accepted wildlife management guidelines for beaver. There is no WDNR tagging requirement or bag limit for the beaver trapping season, and in 2014, they discontinued all population counts.”
“To avoid being sued, APHIS responded to our lawsuit by August 17,” Boucher said. “We are hopeful that this will cause all stakeholders, and especially WDNR to review and revise the ongoing outdated beaver elimination program.”
Beaver management
Boucher said there have been many advances in the science of beaver management in recent years. He said that what is key is to see individual watershed sub-basins like the cells of an organism.
“To stabilize the land and rebuild biodiversity, we need to manage each sub-basin individually,” Boucher said. “Each sub-basin should be managed to promote the goals of the Clean Water Act in promoting biological integrity.”
Boucher said that trapping regulations should be guided by science, and managed by geolocation techniques. He said examples would have time in, time out, sets and route. In the process, with recording data and tagging with photos, the information obtained could be used for research, and identification of the take – kit, yearling and adult.
Boucher also explained that there have been advances in the building of ‘beaver dam analogues,’ which use a system of upright poles placed across a waterway, interspersed with brush. This structure simulates the creation of a beaver dam, and can help encourage beavers to live in a preferred location and make relocation of beavers more successful.
“We also need more public education on co-existence with beavers,” Boucher said. “For instance, if a landowner has a tree they want to protect, it can be as simple as placing a wire mesh circle around the base of the tree.”
Boucher said there is also evolving science on managing the drainage of beaver ponds to prevent nuisance flooding. This can allow landowners to manage water levels in times where there is too much water in the system, and in times where there is too little water in the system. Devices, constructed by trained professionals are referred to as ‘infrastructure flow devices.’
The other management tool described by Boucher is simple live trapping and relocation of beavers. He said this would ideally occur in the summer months, and involve the whole beaver family. Through preparation in the construction of a ‘beaver dam analogue,’ the beavers can be relocated to a place in the watershed where they cause less conflict with humans, and provide the ecosystem benefits that their ponds produce.
Steps forward
In summary, Boucher detailed things that citizens can do to produce a beaver management plan in the state that allows us to capture their ecosystem services for the benefit of humans, and allow for co-existence between beavers and humans:
• become a ‘Beaver Believer’ and encourage others to become one too
• talk with elected representatives to promote legislation and policies aimed toward co-existence and beaver protection
• promote non-lethal management
• continue learning, and stay engaged.
