Tumwater LMD amends scope to add full-lake fluridone treatment for Barnes Lake

The Tumwater Lake Management District (LMD) steering committee voted to amend the contractor scope of work to include a full-lake fluridone (Sonar) treatment for Barnes Lake and a subsequent ClearCast application to address nuisance emergent plants such as water shield and white water lily.

The committee approved the change by voice vote after staff recommended the two-step approach. Consultant Scott told the panel, “I am recommending for the sonar treatment for, this year, instead of doing the aquifol or the diquat, but still doing, the clear cast for, water shield and white water lily.”

The change shifts the LMD’s recommended primary systemic treatment from spot or contact herbicides to fluridone, a systemic product marketed as Sonar. Committee members discussed operational and environmental implications before voting. Participants raised concerns that pellet-style or other treatments could release carbon dioxide and reduce dissolved oxygen — a particular risk in shallow portions of the lake —…