News that Capitol Lake is infested with the New Zealand mudsnail is terribly disconcerting because the invasive species has no natural enemies and can wreak havoc with native snails, mussels and invertebrates that are crucial food sources for fish and other aquatic life.
State wildlife officials are surveying the lake and checking out whether they have migrated to the Deschutes River, Black Lake and Percival Creek before deciding the next course of action.
The best thing South Sound residents can do to help wildlife officials in their eradication efforts is to stay out of Capitol Lake to ensure that the tiny snail is not transported to other freshwater sources.
Capitol Lake is off limits to people and pets until further notice, and state officials will add patrols to ensure that the ban on lake use is strictly adhered to.
Sign Up and Save
Get six months of free digital access to The Olympian
According to Fish and Wildlife officials, the pesky mudsnail is native only to New Zealand, but was first discovered in the Snake River in Idaho in 1987. By 1997 large concentrations of the invasive species were found in the Madison River in Yellowstone National Park.
How the mudsnail got into scenic Capitol Lake in the heart of Olympia is anyone’s guess. But once introduced into a lake or river, the New Zealand mudsnail can quickly take over from native species at the bottom of the food chain. The mudsnail has been known to survive a trip through the digestive system of fish.
From 1/8 inch to 1/4-inch in length when fully grown, the cone-shaped mudsnails can survive a broad range of water temperature, salinity and water quality, according to Fish and Wildlife officials. Unlike New Zealand, they have no natural parasites or predators here. They can live without water for more than a day and have been known to survive on a damp surface for as long as 50 days.
And the asexual mudsnails are extremely prolific.
Fish and Wildlife officials say that one snail can start a whole new population. One snail can produce 230 new snails in a year. By year two, there are more than 52,000 snails, with 12 million by year three and by year four more than 2.7 billion snails can carpet the bottom of a lake or river. All that in four years from one snail.
It’s easy to see why Fish and Wildlife officials want to contain the mudsnail to Capitol Lake while they develop a strategy to combat the species.
Fish and Wildlife officials have found mudsnails in concentrations as high as tens of thousands per square meter in the 260-acre lake, according to Allen Pleus, Department of Fish and Wildlife aquatic invasive species coordinator. “Based on those concentrations, it’s probably been in the lake about two years,” Pleus said.
State officials need the public’s assistance in combatting the mudsnail and stopping their spread. While the trails and parks around the shore of the lake are open for public use, no person and no pet is allowed into the water.
“These tiny snails can be transported in a pant cuff, on boots, kayak equipment or in your dog’s foot pads or fur,” Pleus said. “That’s why we need the public’s support in preventing the problem from spreading to other waters.”
Banning use of Capitol Lake is a reasonable request given the circumstances. Residents must stay out of water until Fish and Wildlife officials adopts a plan — either biological or chemical — to control the mudsnail population, and give the all-clear.