Aquatic Invasive Species (AIS)
Lake Tahoe’s original ecosystem was very simple, and consisted of only one predominant predator. Over time, some non-native species have been intentionally introduced to increase sport fishing or enhance ecosystem resources. Invasive species, non-natives that are harmful to the ecosystem, have also been introduced through unknown vectors. Click here for Lake Tahoe's food web and introducions from the past 100 years.
Aquatic Invasive Species harm Lake Tahoe by:
1. Severely decreasing recreational uses, such as swimming, boating, water-skiing, and fishing
2. Degrading boats by clogging propellers and cooling intakes
3. Facilitating invasions of other non-native species
4. Altering nutrient cycles and increasing algal growth in the lake by adding phosphorous to the water column thus contributing to overall clarity decline
Species of Concern
Presently in Lake Tahoe:
Eurasian watermilfoil
Curly leaf pondweed
Large mouth bass
Bluegill
Asian clam
Bull frogs
NOT Presently in Lake Tahoe:
Zebra mussel
Quagga mussel
New Zealand mudsnail
Native vs. Invasive Mollusk Identification Key
Native vs. Invasive Aquatic Plant Identification Key
Native and Invasive Fishes of the Lake Tahoe Basin
Current Projects
Asian Clam Removal Project
In 2010, the scope of the Asian clam removal project was amplified to include future possibilities of eradication and large-scale control. The project is a multi-agency collaborative effort with multiple funding sources. In July, two-½ acre plots of thin rubber matting, 45 mil pond liner, were placed on the lake bottom along the southeast shore of the lake near Lakeside Marina and in Marla Bay in order to starve the Asian clams of dissolved oxygen. The forty-two 10' x 100' barriers were then removed in early November. In order to install the barriers, a work barge lowered the rolls of rubber into the water and divers staked the rolls in place with rebar. Researchers from University of California, Davis (UC Davis) and University of Nevada, Reno (UNR) will monitor the experimental plots for the next year to determine whether or not Asian clam populations are reestablishing. The goals of the project have been to understand the effects of the mats on Asian clams and the feasibility of using the treatment in other areas of the lake. In 2011, the project expanded to Emerald Bay where a small population of Asian clams has colonized at the mouth of the bay. Tahoe RCD will continue to manage and coordinate these efforts in collaboration with our partners and funders: UNR, UC Davis, U.S. Fish and Wildlife, Tahoe Regional Planning Agency, CA State Parks, Nevada Department of Environmental Protection, Lahontan WQCB, and Lake Tahoe Water Purveyors.
Aquatic Weed Removal Project
Aquatic weed removal continued in 2011 in Emerald Bay. The removal effort is a collaborative effort between the Tahoe RCD, TRPA, and the California Department of Parks and Recreation. Work has been conducted near the Vikingsholm swim beach and pier, the Parson's Rock area, and near Avalanche Beach. In the summer of 2011 we deployed 7,000 square feet of bottom barrier at Parson's Rock and over 13,000 square feet of barrier at Avalanche Beach. Significant diver-assisted hand removal of invasive weeds was performed and nearly 100% of the invasive weeds at Parson's Rock have been either covered with barriers or removed by hand. Previous work has shown near-eradication of weeds (particularly Eurasian watermilfoil) in the Vikingsholm swim beach area and we are optimistic that we can achieve the same results at Parson's Rock and Avalanche Beach.
Aquatic weed removal efforts also took place at Elks Point Marina in April and September 2010. The treatment included diver-assisted hand removal to remove large infestations of Curlyleaf pondweed and Eurasian watermilfoil in the marina. Continued removal efforts will need to occur to eradicate the localized invasive weed populations in the marina.
Veliger Monitoring
In 2010, a veliger monitoring program was initiated by the Tahoe Regional Planning Agency, with assistance from Tahoe RCD. Veligers are the larval stage of bivalve mollusks which includes Quagga and Zebra mussels, two potential invaders of Lake Tahoe. Monitoring is an essential element to ensure that the Watercraft Inspection Program has been effective in preventing Quagga and Zebra mussels from establishing populations in Lake Tahoe. Eight locations were surveyed biweekly from late June until the end of September; the eight locations included Elks Point, the Tahoe Keys, Emerald Bay, Meeks Bay, North Tahoe Marina, Sand Harbor, Obexers Marina, and Cave Rock. Sampling consisted of eight vertical plankton tows at each site, and the samples were sent to a laboratory to be analyzed. All of the samples returned with no Zebra or Quagga mussel veligers present.
About Our Partners
The Tahoe RCD is a part of the Lake Tahoe Aquatic Invasive Species Working Group (LTAISWG). This group was formed to better share resources and information, standardize methods for treatment and data collection, perform coordinated education and outreach activities, obtain grants, and organize effective control efforts.
Meeting Minutes: Lake Tahoe Aquatic Invasive Species Working Group:
Click here to access the Lake Tahoe Region Aquatic Invasive Species Management Plan