Scientists, locals partner to combat Lake Tahoe’s invasive species

INCLINE VILLAGE, Nev. — Public agencies are teaming with private residents and business owners to combat nonnative species threatening some of Lake Tahoe’s famed nearshore ecosystems.

The partnership follows a strategy outlined in conjunction with University of Nevada, Reno, scientists and the Tahoe Resource Conservation District.

The collaboration between the scientists and lakefront and marina business and homeowners focuses on Tahoe’s nearshore waters, which are areas up to about 50 feet deep.

“With a serious and sustained effort, we can protect Lake Tahoe’s native species and the health of Tahoe shorezones from unwanted invasive species,” said Sudeep Chandra, a biologist and limnologist at UNR and co-author of the plan.

The plan focuses on the lake’s most prolific invasive species, which include Asian clams, Eurasian water milfoil and several types of warm-water fish and plant species, which have established several locations along the lake’s south and northwest shores, said UNR biologist and plan co-author Marion Wittmann.

“It’s like having a lot of cancers around the body,” Wittmann said. “Until they are all gone, you have to make sure they are not coming back.”

Aggressive removal

The changing ecosystem points to a phenomenon called eutriphication, Wittmann said, in which an ecosystem once nearly devoid of nutrients — not unlike Tahoe — becomes enriched with nutrients, typically containing nitrogen, phosphorus and sometimes both. The process can occur naturally in lakes as they age through geological time.

The work is daunting, Wittmann said, and a “job for a person who is determined and focused, and can cope with failures along the way to see the success to its end.”

In 2009, Dan Shaw, an environmental scientist with California State Parks, worked with University of California, Davis, to remove more than one million plants — more than six acres, he said — of invasive plant species from Emerald Bay.

Shaw has been working on the preservation of Tahoe’s nearshore areas from Emerald Bay through Tahoe City, and everything in between.

“When we started our weed work, it seemed insurmountable,” Shaw said. “But whenever you undertake a project like this, you never know what you’re going to get.”

The approach will call for “aggressive removal projects” at areas including Tahoe City, Meeks Bay, Crystal Bay and a number of areas along Tahoe’s south shore.

The areas of growth do seem to be localized to the nearshore, Shaw said, as the lake’s deeper areas continue to be devoid of plant growth. However, as far as other non-native species, like fish and some amphibious creatures, it’s unclear how prolific their spread has become.

‘It could be a prolific issue’

Of the nearly 30 nonnative aquatic species established in the Lake Tahoe watershed since the 1800s, the plan will target three for feasible action, Wittmann said: Eurasian water milfoil, curly leaf pondweed and warm-water fish.

Identified for control or eradication actions are the signal crayfish and the American bullfrog.

The plan notes that Asian clams and mysid shrimp, established at several locations at the south shore of the lake, have been identified as having “no feasible control options at this time.”

“It could be a prolific issue,” Wittmann said. “We definitely know from other places in the country these species are bad for lakes, rivers and reservoirs.”

Wittmann added the plan as it is currently written is based on a 3- to 5-year period, but it’s likely the overall project will take longer than five years.

Efforts made in coordination with residents in the north shore have been collaborative thus far, Wittmann said.

After a trip to Crystal Bay last week, Wittmann said efforts that began back in 2012 have resulted in a major difference.

“We saw a handful there,” Wittmann said. “We’re contacting locals there and we work with them to continue to maintain those areas.”

Shaw agrees the coordination he experienced cleaning areas around Emerald Bay were equally collaborative, but it’s a job that won’t likely end any time soon.

“The key is to not let anything in there in the first place,” he said. “The weeds will always be coming into Emerald Bay, so it is something that I will constantly be dealing with.”

Funding the plan

The current plan is funded through the California Tahoe Conservancy, in large part using fees paid by Tahoe lakefront homeowners and marinas in California.

The fees come from an appropriation made available through the passage of Senate Bill 630, which was approved in October 2013.

The bill redirects nearly $1 million in state fees for buoys and piers from the state’s general fund to Tahoe-specific projects.

This year, those funds will support the nearshore project and help establish a bistate science council.

The plan is one of several approaches to combat invasive species, such as the Lake Tahoe Aquatic Invasive Species Management Plan, a coordinated effort with volunteers to identify and survey the spread of aquatic invasives around the lake.

“This implementation plan is a direct extension of the (aquatic invasive species) management plan, giving boots-on-the-ground guidance to agencies,” Chandra said.