Tugboats in Kenmore's narrow channel haul barges with parts for the 520 Bridge, and some of those tugs stirred up sediment that then settled over North Lake Washington.
The sediment could have potentially settled in areas with protected salmon habitats, in swimming areas and in a marina where boat owners say the accumulated sediment makes it hard for some to get out.
A federal lawsuit claims it's an illegal discharge of dredged material and that citizens are "seriously concerned about the effects on water quality, wildlife and recreation." The suit also lists 66 days when those tugs stirred up muck and asks for a fine of $37,000 per day.
"I feel very encouraged about the lawsuit being filed, and the statement I think it makes is that when there is a wrong, the citizens have a right to make it right," said Elizabeth Mooney with the Waste Action Project.
Tug operators Kiewit/General/Manson are also in hot water over delays with the 520 Bridge work. In a statement, the tugboat operators say they're not ignoring environmental issues.
"We take our environmental responsibilities seriously and will continue to work with DOE for the remainder of the project to ensure the quality of the water in the lake is not affected," the statement reads.
In the past, the group has said it has kept the state informed on everything it was doing and, at one point, switched to low draft tugs to alleviate much of the problem.
KOMO News has learned a second lawsuit is coming against three federal agencies for allowing the sediment to impact salmon habitat and other wildlife.
The National Marine Fisheries Service has reopened its review of the tugboats and the sediment.