by Richard Uhlhorn
Four Peaks Environmental Services conducted an invasive aquatic species survey on Lake Chelan and found 520 acres of Eurasian Milfoil and Curley Leaf Pondweed along the shoreline of Wapato Basin and stretching into the lower regions of the Lucerne Basin where there is heavy recreational boat use.
This increase of invasive species over the past eight years has increased concerns on how to manage the invasion. The Lake Chelan Research Institute (LCRI) began looking at methods of managing this issue and settled on DASH (Diver Assisted Suction Harvesting) as the preferred method of removing the invasive species from the lake bottom.
With $25,000 of private funding the LCRI hired Lake Defense Force to conduct a sample test of two areas over a six day period… Key Bay and Minneapolis Beach. This test will help determine an Integrated Aquatic Management Plan for the lake.
The airlift used by the team pulls invasive species up by the roots. Once captured, it is bagged for removal. According to Alex Garry, Lake Defense Force General Manager, the dive team can suck up between 1,500 and 5,000 square feet per day.
DASH is an alternative to using chemical applications to remove milfoil and pond weed. The use of chemical herbicides is not a preferred method in Lake Chelan.
The diving company comes back to a treated area and removes any recurring bloom on the bottom by hand. “We have, over time eradicated invasive species from lakes,” said Garry.
Because Lake Chelan is a reservoir which is lowered in the winter for power production, much of the invasive species is killed by freezing. This year’s cold spring has delayed the growth of invasive plants in Lake Chelan. Much of the plants removed were thought to have sprouted on the bottom within the last several weeks.
LCRI executive director, Phil Long, stated that the test was extremely successful and will help determine a management plan and financial resources needed to implement it. “We hit high use areas which confirmed the continued spread of invasive aquatic plant species in Lake Chelan,” stated Long. “It’s interesting that a lot of the plants are blooming under anchored boats.”
Over the five and half days Lake Defense Force operated, they removed 900 pounds (20 bags) of milfoil and pond weed, most of which was removed from Minneapolis Beach.
Lake Chelan Research Institute conducts monthly water quality research on the lake and is partially funded by local government entities. Organizations and individuals can donate money and time as volunteers to help keep the lake quality at its optimum. Visit https://lakechelanresearchinstitute.com/ for more information.
Another group helping educate the public about Lake Chelan is the Keep It Blue Program at https://www.keepitbluelakechelan.org/.