The Nooksack Indian Tribe has monitored glacial sediment discharge for several years in the Nooksack River watershed, focusing on areas that could influence water quality and the reproductive success of threatened spring chinook.
The tribe collects continuous turbidity data at three stations and 20 remote sites. Tribal technicians also sample suspended sediment at each site.
“This work is being conducted to establish a baseline that will serve as a reference for a likely shift in sediment dynamics with climate change,” said Oliver Grah, water resources program manager for the tribe.
A series of landslides in 2013 had the tribe concerned about the effects of increased sediment on threatened chinook salmon and steelhead. After debris flows along the Middle Fork Nooksack River in the spring, turbidity at the Nugent’s Corner Bridge on the mainstem exceeded the maximum levels the tribe’s automated turbidity meter could record.
By August, the turbidity on the mainstem had returned to levels typical for the season.
“The North Fork and Middle Fork are always turbid this time of year because they’re glacially fed,” said Tom Cline, water quality supervisor. “The South Fork is less turbid because it is fed by snowmelt, but it also suffers from low flow and high temperatures in August and September.”
Most of the sediment monitoring is funded by a GAP grant, base CWA 319 and competitive 319 funds, as well as BIA, NWIFC and the North Pacific Landscape Conservation Cooperative.
“Combined funding from different grantors provided funding leveraging,” Grah said. “Also, all of this work is being shared with and vetted through our Water Resources Inventory Area watershed management project and with other tribes and stakeholder groups.”