The Cascade Water Alliance today announced that the past two years of milfoil treatment on Lake Tapps have been successful and a third round of chemical treatment will not be necessary this summer.

Cascade crews recently found about 95 percent of the milfoil recorded in 2010 is now gone.

“We are extremely pleased with the success of the program and how quickly and dramatically milfoil has been reduced on the lake. We expected to conduct a third year of chemical treatment,” Capital Projects Director Jon Shimada said in a press release, “but it looks like that won’t be necessary.”

No widespread use of chemicals to treat the milfoil is planned for this summer. Instead, in selected areas where milfoil remains, divers will hand-pull plants. If divers find problematic areas, chemical treatment will take place on a very limited basis.

Given the program’s success, Cascade will now shift its approach from aggressive treatment to ongoing maintenance, regularly monitoring milfoil growth on the lake. The cooperation of residents and boaters is essential to the long-term goal of removing milfoil from Lake Tapps.

“We’re asking boaters to check for and remove any trace of milfoil if they are coming in from other lakes where there might be an infestation,” said Joe Mickelson, Lake Tapps manager. “Even the smallest trace of milfoil on a boat can propagate in the lake and cause future problems.”

Boater and residents who find milfoil growing in Lake Tapps should call Cascade at 1-877-453-0930.

Eurasian Water milfoil is a non-native, invasive aquatic plant that spreads rapidly and crowds out native plants by forming dense surface mats. According to the Washington State Department of Ecology (DOE), milfoil starts spring growth earlier than native aquatic plants and can out shade these beneficial plants. Because it is widely distributed and difficult to control, DOE says milfoil is considered the most problematic plant in Washington State.

Cascade Water Alliance, owner of Lake Tapps, began a multi-year program to address milfoil growth in 2010 by treating 400 acres of the lake that were found to be infested.