Indicator
Aquatic Invasive Species Prevention
2019 Evaluation
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This standard articulates one of the broad goals of the AIS program, preventing new AIS from entering the lake. Since 2008, the nationally recognized Lake Tahoe Watercraft Inspection Program has prevented new AIS from entering the lake. Under the program, all motorized watercraft are inspected (and cleaned when necessary) prior to launch to prevent the introduction of new AIS. The prevention program also emphasizes preventing the transport of already established aquatic invasive species to other lakes within the Region. 

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Status

Watercraft Inspections for Invasive Species Prior to Launch

The chart information is sourced from the EIP performance measure Watercraft Inspections for Invasive Species which can be found here: https://www.laketahoeinfo.org/Indicator/Detail/16/Overview#

 

 

2019 Evaluation
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Status
At or Somewhat Better Than Target
Trend
Little or No Change
Confidence
High
Applicable Standard
WQ8: Prevent the introduction of new aquatic invasive species into the region’s waters.
Key Points
  • No newly introduced aquatic species have been documented in Lake Tahoe since the standard was adopted in 2012.
  • Prior to the adoption of the standard, 30 non-native aquatic species were already established in the Tahoe Basin's waters.
  • To ensure no new species become established all boats are inspected prior to entering Lake Tahoe. Inspectors decontaminated an average of 4,155 boats annually between 2016 and 2019 to prevent AIS introductions to the lake.
Evaluation Map
Description

The location of watercraft inspection stations.

About the Threshold
Aquatic Invasive Species (AIS) are non-native organisms that threaten the abundance and diversity of native organisms in Lake Tahoe. Non-native species have been intentionally and unintentionally introduced to the Lake Tahoe Region over the last 150 years. Prior to 1960, a number of species were introduced by managers to augment recreational opportunities. These include a variety of salmonid species including rainbow trout (Oncorhynchus mykiss), Lake trout (Salvelinus namaycush), Kokanee salmon (Oncorhynchus nerka), brook trout (Salvelinus fontinalis), and brown trout (Salmo trutta). The last intentional introduction was of a salmonid prey species, mysid shrimp (Mysis diluviana) in the 1960s. A number of species were likely introduced non-officially by individuals and became established sometime in the mid-1980s and new introductions continued through the first decade of the 20th century. These include warm-water fish species, including bluegill (Lepomis macrochirus), largemouth bass (Micropterus salmoides), aquatic plants Eurasian watermilfoil (Myriophyllum spicatum) and curlyleaf pondweed (Potamogeton crispus), and Asian clams (Corbicula fluminea). The presence of these species continues to threaten native taxa of the lake and is a nuisance to users of the lake. The presence of AIS also results in economic impacts in the Region with potential costs to tourism, property owners, boaters, and maintenance estimated at between $22 to $78 million per year. In December 2012 TRPA adopted the current standard related to the management of AIS in the Region. The presence of aquatic weeds increases nutrients in the system which may impact nearshore clarity.
Non-native species have been both intentionally and unintentionally introduced to Lake Tahoe over the last 150 years. Habitat modification such as channelization and modification of the Truckee Marsh for the Tahoe Keys also created micro-environments within the lake that may be more suitable for colonization by AIS. Climate change further threatens to alter the lake’s physical environment, with the potential for making further AIS establishment more likely.
Delivering and Measuring Success

EIP Indicators

Example EIP Projects

Local and Regional Plans

Rationale Details
Every year, there are approximately 30,000 watercraft seal inspections at boat launches around the lake, ensuring all boats entering the lake are compliant with AIS regulations. Any vessel not cleaned, drained, and dried is deemed to be a high risk of harboring some form of aquatic invasive species and is decontaminated. There are an estimated 30 non-native aquatic species that are established in the Region’s waters. No new aquatic species have been documented in Lake Tahoe since the standard was adopted in 2012.
No new aquatic invasive species have been found since 2012. Therefore, the trend was determined to be "no change".
Confidence Details
High. The watercraft inspection program performs seal inspections on thousands of boats per year prior to launch and decontaminates all boats that are found with AIS or boats that are not clean, drained, and dry. The Lake Tahoe Watercraft Inspection Program is highly reputable.
High.
High.
Additional Figures and Resources

No photos available.

No documents available.