Publication Summary

During the fall of 2001, the Washington State Department of Ecology conducted a sediment study in the lower Nooksack River near the city of Ferndale. The primary objective was to determine if increased NPDES permit limits for metals in Ferndale′s Wastewater Treatment Plant (WWTP) effluent increase accumulation of metals in the river sediments.

During the fall of 2001, the Washington State Department of Ecology conducted a sediment study in the lower Nooksack River near the city of Ferndale. The primary objective was to determine if increased NPDES permit limits for metals in Ferndale′s Wastewater Treatment Plant (WWTP) effluent increase accumulation of metals in the river sediments.

Nine sampling sites were selected in the vicinity of Ferndale′s WWTP outfall. Sediments were collected from depositional areas and were analyzed for grain size, percent solids, total organic carbon, 13 priority pollutant metals, barium, manganese, and iron.

Total organic carbon values were low. Seven of the nine samples were composed primarily of coarse sediments. All 16 metals were found in low concentrations. Levels of lead and copper, the two metals raised in the 1999 NPDES permit, were well below sediment quality guidelines and typical background concentrations for freshwater sediment in Washington State. All other metals tested, except iron and nickel, were also below the sediment quality guidelines. Levels of iron and nickel appear to have no relationship to the location of the WWTP outfall site.

The results show no accumulation of metals due to the WWTP outfall. Therefore, the increased permit limits for the WWTP outfall do not appear to present a threat to the benthic community of the lower Nooksack River.

Link to EIM data for User Study ID MROOS001