Report: Officials stay one step ahead of aquatic invasives

By Kathryn Reed

STATELINE – Sixty-three percent of the vessels inspected in 2011 had to be decontaminated before being allowed to enter Lake Tahoe.

Of the 30,400 boats that were launched, 7,600 had to be checked for aquatic invasive species, with 4,800 of those needing to be decontaminated. While most of the boats originated in California or Nevada, Utah, Oregon and Arizona were the states with the next highest number of boaters.

Overall, that was 9,000 more than in 2010. Ted Thayer, aquatic invasive species program coordinator for the Tahoe Regional Planning Agency, said how data is collected changed between 2010 and 2011, so while marinas reported business was up, it may not have been as significant as the AIS program numbers indicate.

Thayer on Jan. 11 updated the Advisory Planning Commission about how the AIS program worked last year. The TRPA Governing Board will hear the presentation at its Jan. 25 meeting in Stateline.

“This was a very successful year for the program,” Thayer said.

The program since its inception in 2007 keeps evolving. Prevention, monitoring and controlling are the mantras. Weeds, Asian clams and warm water fish are the predominate invasives that partners in the program are trying to eradicate, control or prevent from reaching Lake Tahoe. Fallen Leaf and Echo lakes also come under the purview of this program.

But what makes Fallen Leaf Lake different than Tahoe is no aquatic invasive species have been found in that body of water off Highway 89. Motor boats are inspected at the marina, with a roving inspector checking non-motorized watercraft that are mostly launched from the U.S. Forest Service-owned campground at the other end.

The Fallen Leaf Lake report shows of the 428 inspections, 24 vessels came from lakes known to have quagga or zebra mussels, or New Zealand mud snails.

Other regional bodies of water like Donner Lake and Lahontan Reservoir are outside TRPA’s control. However, as funding these programs becomes more difficult with the disappearance of federal dollars, a broader regional approach to aquatic invasive species is likely to occur.

Thayer said this could mean one day the decontamination station on the North Shore being outside the basin and closer to Truckee, and possibly having a station in Carson City instead of at the top of Spooner Summit. Those are just ideas now. Eventually permanent stations are the goal.

TRPA is not alone in the AIS program. A number of agencies and groups are involved, including, but not limited to, Tahoe RCD, UC Davis, California Department of Fish & Game, and Nevada Department of Wildlife.

In 2011, 6.51 acres of Emerald Bay were treated for invasive weeds. This compares to the 1.1 acres treated in 2010. Commercial divers helped with the removal of the plants.

Milfoil is one of the biggest problems throughout Lake Tahoe, especially in the lagoons of Tahoe Keys on the South Shore.

“This project was designed to test multiple methods,” Thayer said. “Tahoe Keys is a very different environment. There is a lot denser growth of weeds, with a lot of boat docks.”

A dye that is invisible to the human eye was used in this area. Thayer praised Lahontan Regional Water Quality Control Board’s decision late last year to allow herbicide use in Lake Tahoe on occasion. He said this may be needed for the Keys.

Using a barrier to suffocate Asian clams was most effective in summer, but worked in the winter as well – it just takes longer when the water is colder. Marla Bay is where the winter tests were done.

Knowing this works means the material could be used in areas with a ton of boat activity – like Ski Run Marina area – that during the summer make it dangerous for divers to work.

A pilot program to rid the mouth of Emerald Bay was less successful because of the topography and water exchange.

A warm water fish eradication program encompassed about 14 acres, mostly in the Tahoe Keys. An electrical charge was sent into the water that stunned the fish. They were then scooped out of the water – all 12,000, which weighed 2,157 pounds.

The small mouth bass, according to Thayer, is what concerns officials the most. They can threaten the mackinaw. Even though the mackinaw is not native — it was introduced as a sport fish — it is not considered an invasive species.

A change going forward is creating a lakewide permit for AIS treatments. Thayer said that should be in place this year.

In the past, engines were flushed for one minute to decontaminate them. That will decrease to 10 seconds this year. Thayer said this is to conform with industry standards. For boaters it will speed up the process and decrease potential propeller damage from the decontamination process.

Monitoring the water at 60 locations throughout Tahoe, Fallen Leaf and Echo is how scientists determine if invasives have reached those bodies of water. The most threatening are quagga and zebra mussels. They have not reached any of these waters.

To keep the program going, an increase in watercraft inspection fees is being proposed. The Governing Board will make that decision. The document linked here is what was presented to the APC and is likely to change before it reaches the Governing Board in 12 days.