Aquatic invasive species hard to keep in check

By Kathryn Reed

INCLINE VILLAGE – Aquatic invasive species are never going to disappear completely, but it is possible to manage them and possibly keep some from reaching Lake Tahoe area waterways.

That was the message Thursday during a talk from various experts at the Tahoe Environmental Research Center at Sierra Nevada College in Incline Village.

Eurasian milfoil has been here for years – predominately in the Tahoe Keys. New Zealand mud snails are also in Lake Tahoe. What aren’t here are Quagga and zebra mussels. Those are two of the major threats to any body of water because they have yet to be eradicated from waters they’ve invaded.

With Lake Tahoe seeing about 15,000 boats a year, and that number on the rise, inspecting every boat that enters the lake is the only way to keep nonnative species away. In 2013, about 4,000 boats were decontaminated before entering Lake Tahoe.

Tahoe Resource Conservation District does the inspections in the basin. More Tahoe-only boats are coming through, which means they are not going to another body of water. This then reduces the threat of Tahoe being contaminated.

The mussels can threaten water in-take locations, ruin the ecological diversity and potentially have an economic impact if they take hold because people will not re-create where they are.

The Thursday forum on the North Shore featured speakers from TRCD, Tahoe Regional Planning Agency, Trout Unlimited, California State Parks, Tahoe Keys, and League to Save Lake Tahoe.

One of the problems is that funding is running out to maintain the prevention programs that are in place. It costs about $1.5 million a year for the Lake Tahoe prevention program. Half is from fees, the other comes half from the federal government via the land sales in Southern Nevada. Those dollars are about exhausted.

The overwhelming message is that people accessing any lake need to be aware of the vessel they are using or gear.

The latter is important because it is anglers who are most prone to transport the New Zealand mud snails via what they are wearing. They are so tiny and asexual that it just takes one to make many. They were first documented in the Truckee River in 2013, but likely had been there for a few years.

They can live up to 24 days without water and 50 days in damp conditions, according to Dave Lass with Trout Unlimited.

The mouth of Emerald Bay had a huge Asian clam problem a few years ago. Mats were laid down as a way to suffocate them. It worked.

Dan Swan with State Parks showed dramatic photos of what Emerald Bay looked like in 2010 compared to 2013. The first year the waters were murky, brown, full of milfoil and looked almost like any California lake. Three years later the water was nearly pristine, the lake bottom could be seen and the invasive weeds were gone.

“We didn’t find a single milfoil at the end of last year,” Swan told the nearly 80 people in attendance.

Milfoil is a massive problem for the Tahoe Keys on the South Shore. The homeowners association has four harvesters that essentially mow the prolific weed. Harry Dotson with the Keys said 12,000 cubic yards of milfoil were harvested last year.

The development of the Keys turned what was the most sensitive marsh area in the Lake Tahoe Basin into a shallow warm water system. This in turn allowed for nonnative fish to thrive.

Patrick Stone with TRPA said last year killing these fish with electronic currents took out more than 50,000 nonnatives, mostly large mouth bass and blue gills.

The message to the public is the way they can help is to become a Tahoe Keeper if they are using a non-motorized watercraft, be part of the League’s Eyes on Lake Tahoe program, and to make sure all boats are cleaned, drained and dry before entering any body of water.