Barnes Lake committee approves full fluridone treatment and IVAMP despite hitting reserve

The Barnes Lake Management District approved a proposal to apply a full-lake fluridone treatment and fund an integrated aquatic vegetation management plan (IVAMP), the committee agreed during its meeting.

Committee members voted in favor of “option B,” which replaces the contact herbicide plan with a systemic fluridone application and includes development of an IVAMP and separate spot treatments for water lilies. City staff said the option will largely deplete the district’s cash balance but reflects previously planned fee assessments intended to cover periodic expensive treatments.

The approval followed discussion of two primary approaches: continuing with contact herbicides (diquat or endothal) and spot-spraying where plants are present, or doing a systemic fluridone application across the lake to control bladderwart (botanical name not specified in the meeting). Staff and the consultant team advised that bladderwart tends to move and float, making spot treatment less effective over time. Fluridone is systemic and targets the whole plant, including roots; contact herbicides act more locally and are generally lower cost.

City of Tumwater water resources specialist Dave Congheiser and program manager Patrick Soderberg outlined practical and timing differences. They said fluridone typically requires maintaining a target concentration in the water column for several weeks and often requires at least two applications to remain effective. The committee was told a typical target concentration example discussed was about 4 parts per billion and that treatments often are applied when water temperatures reach roughly 63–65°F, with plant emergence usually occurring in May–June in recent years. Soderberg and staff also noted that Washington state “Ecology” timing restrictions limit when certain contact herbicides can be applied (committee members said contact herbicides generally cannot be applied before July), whereas fluridone can be applied earlier in the season.

Cost and budget timing were central to the discussion. Committee members expressed “sticker shock” at the immediate impact on the district balance; staff said pursuing option B would reduce the account to roughly $3,700. Staff and members agreed the district had built assessments intentionally to cover occasional expensive years. The IVAMP was quoted in discussion as an estimated $15,000 and was described as a once-every-10-years expense; committee members noted that some of the IVAMP work might be priced lower if the proposer (Aquatechnics) also performed the plan update.

Members also discussed logistics that could affect scheduling, including availability of an airboat and a temporary boat ramp solution while permits for a permanent ramp are pending. Staff indicated there is a temporary workaround for launching the applicator’s boat and that Aquatechnics may be able to schedule earlier-season work, potentially in June or early July, rather than late August as in prior years. Once the motion passed by voice vote, staff (Congheiser and Soderberg) said they would email Aquatechnics the following day to secure calendar availability.

The committee’s formal action does not specify exact treatment dates or the final work plan; staff and the applicator will finalize scheduling and the number of return applications needed to achieve the required fluridone concentration.

Votes at a glance: the committee approved option B by voice vote (three recorded “ayes”; no recorded opposition). Names for each aye were not specified in the meeting record.