Culverts can cut off steelhead from habitat

The Nisqually Indian Tribe is working with the South Puget Sound Salmon Enhancement Group to assess how well steelhead and other salmonids will be able to pass through culverts in the Nisqually watershed.

“We can protect and restore habitat throughout the watershed, but just one impassible culvert means steelhead won’t be able to get to that habitat,” said David Troutt, natural resources director for the Nisqually Indian Tribe.

Biologists from the tribe and the enhancement group are crisscrossing the watershed, hunting down small and sometimes hard to find culverts. Once located, they’re taking precise measurements to figure out whether adult or juvenile steelhead and salmon would be able to traverse the culvert.

“Even if the culvert looks fairly innocuous, small things like slope or just not enough rocks in the culvert stops steelhead from making it through,” Troutt said.

How culverts at road crossings can hurt salmon is already well documented in the Nisqually because of efforts to restore Puget Sound chinook salmon, which were listed under the federal Endangered Species Act (ESA) in 1999. Led by the tribe, the Nisqually community was the first watershed to produce a chinook recovery plan and has been aggressively restoring habitat since then.

Taking another look at culverts is important because steelhead have different habitat needs. “Chinook and steelhead use different streams,” Troutt said. “Steelhead are more likely to use a smaller stream to spawn in for example.”

Nisqually steelhead were part of the Puget Sound population listed under the ESA in 2007. The culvert assessment is associated with a steelhead recovery plan being developed by the tribe.

Steelhead plummeted in the Nisqually River almost 20 years ago. Tribal and state co-managers would like over  2,000 steelhead to return to spawn every year to the Nisqually, but since 1993, the average return has been less than 600. Decades ago, the Nisqually River had one of the strongest run of steelhead in Puget Sound; more than 6,000 would return every year.

The Nisqually is also one of two watersheds funded by the Puget Sound Partnership to begin writing locally based steelhead management plans. Like the Puget Sound Chinook Recovery Plan, these local plans would provide the basis for NOAA’s regional plan.

“Documenting, and we hope fixing, these culverts, can mean a lot more habitat available for steelhead here,” Troutt said.