Beavers Contributing to Increased Water Resources

The Suquamish Tribe has noticed that water levels in the wetlands around the Port Madison Reservation have been steadily increasing.

“Beavers have moved into one of the reservation’s biggest wetlands the past few years, building dams and ponds, creating natural reservoirs,” said John O’Leary, the tribe’s water resources program manager. “There’s about 25 acres of open water now.”

For the past 20 years, the tribe has been monitoring water quality and water levels in the Keokuk wetlands and Sam Snyder Creek headwaters, which appear to contribute to local aquifers. This groundwater is an important source of drinking water for the Suquamish tribal community.

O’Leary discovered the beaver dams in 2012 when he noticed water levels rising and sustaining a higher-than-normal level.

“Hydrologically, it appears that the beaver activity is a net positive for the health of the system,” O’Leary said.

This was especially important in 2015, when many communities around Puget Sound were facing dry creeks and decreased water supplies.

“While most folks dealt with nearly dry creeks, the upper part of Sam Snyder Creek was flowing throughout the summer for what may have been the first time in several generations,” he said. “I think the beaver activity contributed to that.”

The dams and resulting ponds reduce peak flows and store water to be released more gradually to the stream. The ponds also supplement the groundwater system, which supports lowland streams, such as Cowling Creek, which supports coho salmon.

“At a time when we’re losing wetlands all over the place to development, it’s nice to see some being restored and in a natural way,” O’Leary said.

One of the few downsides to the extra water is that it limits access to harvest sites for Labrador tea, or “marsh tea.”

The native Labrador plant, from which the leaves are harvested by tribal elders to make "marsh tea."
The native Labrador plant, from which the leaves are harvested by tribal elders to make “marsh tea.”

“It hasn’t been clear if the extra water will impact the ability to collect leaves or drown the plants,” he said.“But we’re monitoring that and talking with elders to make sure they still have access to the wetlands as well as other places.”