In 2005 the Clallam County Noxious Weed Control Board (CCNWCB) conducted a float survey on the mid section of the Sol Duc River (from the Park boundary to Whitcomb-Diimell boat launch on Highway 101). The Snider Work Center was the furthest upstream site found.

In 2006 CCNWCB solicited and obtained 29 landowner permissions from landowners in the mid-section of the Sol Duc. Only one landowner would not give permission to use herbicide. Treatment of the mid-section took place in September and October, mainly on foot except that one day the Quileute Tribe provided a boat and rower to treat sites that could not be accessed by foot. Seventy-one separate sites were treated. All plants treated were Bohemian except for one giant knotweed site and a Himalayan knotweed site near Sappho (the only known Himalayan knotweed on the Peninsula). Knotweed was noted on Bear Creek for the first time.

In 2007 a combined Quileute/CCNWCB crew monitored and re-treated as necessary all of the sites in the mid-Sol Duc. The one landowner who had refused permission in 2006 did allow the crew to treat knotweed on his property from the river. This was an important step, because it was the largest site on the Sol Duc. Crews reported that knotweed was much reduced—sites that had consisted of 200 to 400 canes were down to 20 or 30. Some spray records reported 90% control from the previous year's treatment. Crew also treated the sites on Bear Creek for the first time and spent several days treating a site in Sappho, owned by Rayonier, on both sides of Highway 101.

In 2008 a combined Quileute/CCNWCB crew re-treated the entire river. This was the third year of treatment on the mid Sol Duc and plants were greatly reduced in size and number. Very few sites had plants over five feet tall and epinastic growth was observed in some sites, as a result of previous year's treatments. No Himalayan knotweed, which had been re-treated in 2007, was visible. Herbicide use declined, despite almost 5 gallons being used on sites on Wisen Creek that were treated for the first time in 2008.

In 2009 the 2-person CCNWCB crew worked alone on the mid Sol Duc. Three years of treatment had greatly reduced knotweed populations and the crew reported that on 36 parcels, (out of 62), no knotweed was found. We obtained a new landowner agreement for a site on Bear Creek and the crew injected 30 plants there and sprayed another 40. Other sites on Bear Creek were re-treated, 140 or so plants still remaining (some epinastic). The Rayonier-owned parcels at Sappho still had at least 800 plants, mostly less than 3 feet tall and many epinastic. About 200 plants still remained on Hillstrom Road and were treated. Wisen Creek was treated again—herbicide use there dropped from more than 6 gallons to less than 1. Very few plants were found on any sites other than the ones mentioned.

In 2010 the Clallam County Noxious Weed Control Board did few treatments on the Sol Duc, instead focusing on outreach and landowner education, with the goal of eventually making all landowners responsible for controlling knotweed. We believe this to be the only way to achieve long-term control, since we know our program cannot be funded indefinitely. The furthest upstream infestation, at the Snider Work Center, was treated on September 14th by a CCNWB crew working on Forest Service projects. All sites on the Mid Sol Duc have been treated for four years and are greatly reduced.