The heavy cold snap earlier in December proved to be a big help to state officials trying to limit an unwelcome New Zealand mudsnail population that has infested Olympia’s Capitol Lake.
Officials lowered the lake during a weeklong subfreezing spell that saw temperatures fall into the teens five nights during the Dec. 4-9 period, and state scientists estimated that 40 percent to 60 percent of the tiny rice-sized snails were killed lakewide.
In a summary report on the drawdown experiment, the state Department of Enterprise Services called it “the most effective treatment of New Zealand mudsnails since the pest was first found there in 2009.” It cited the findings of the Department of Fish and Wildlife, which has monitored the mudsnail population and oversaw two previous efforts to kill off the tiny mollusks using the cold.
DES is characterizing the results as more successful than similar efforts in 2009 and 2012.
No one knows precisely why the aquatic invasive species is in Capitol Lake, but it has been contained to the lake areas and has not spread to nearby waters. DES says the snails reproduce asexually, which means just one snail can begin a new population.
The species is considered a problem because it interferes with the food chain, robbing fish populations that compete for the same nutrients in the water.
Brad Shannon: 360-753-1688 firstname.lastname@example.org/politics-blog/