The Sekiu River is 12.5 miles long, with an additional 36.7 miles of tributaries. A watershed analysis has been completed on the Sekiu, and fairly extensive data have been collected for stream temperatures. Most of the areas adjacent to streams in this region have been subjected to timber harvest and removal of LWD from the channels. This has increased the sediment delivery, and in some areas has caused large landslides and debris flows. The Sekiu basin had high levels of sediment fines instream, higher than unmanaged watershed values for the area. Roads and mass wasting are major contributors of the fines, with road density being very high, and was rated as "not properly functioning" in the Limiting Factors Analysis (LFA). A large network of substandard roads and aggressive basin-wide stream salvage operations (log removal) have caused most of the habitat damage. Channelization has occurred in the Sekiu basin, and the Main Line logging road that parallels the mainstem is the greatest floodplain impact in the basin. The road has resulted in channel constrictions in the lower 4.5 miles of the mainstem, causing increased channel instability and a loss of off-channel early juvenile rearing habitat, as well as winter refuge habitat for salmon. While the last large log jams were removed in the 1970's, new log jams were added to the channel as part of 2001 restoration activities. Cedar salvage continues to diminish the majority of the remaining old-growth derived woody debris in the region. LWD is especially low in the South Fork Sekiu; the North Fork Sekiu was rated in the LFA as "good" for functional LWD, but "poor to fair" for the lack of larger key pieces. Streams in this region are highly susceptible to temperature problems because of the low elevation, and naturally low summer flows.
Summer/fall chinook, fall coho, fall chum, sockeye (strays only), winter steelhead and cutthroat have been recorded in the Sekiu River. Temperatures have been above state standards in the Sekiu River. Salmon need cold temperatures and lots of dissolved oxygen to thrive, and these poor conditions will add to the stress caused by other environmental factors in these systems. Fine sediment in streams fills up the "interstitial" spaces be-tween the gravel that fish need for spawning and feeding, and therefore negatively impacts the survival success of salmon.