THE HISTORY OF AIS CONTROL IN THE TAHOE KEYS LAGOONS1
Development of Truckee Marsh into the Tahoe Keys
- Tahoe Keys was developed in the 1960's and 1970’s as a unique, planned-unit-development. The end result was the transformation of approximately 750 acres of marsh land into a 1,529 member Community Association, encompassing 335 town houses and 1,194 home sites.
Infestation & Response:
- Native to Europe and Asia, Eurasian Watermilfoil was introduced to Lake Tahoe and the Tahoe Keys in the 1980s. No one knows how specifically, but it is likely from home aquarium dumping, or transported accidentally by boat.
- Harvesting begins.
Investigation & Harvesting:
- The harvesting and fragment control program continues and grows as the infestation grows.
Curlyleaf Pondweed Detected
- In 2003 a new aquatic invasive species was detected within the Tahoe Keys lagoons. Since being detected it has proliferated throughout the Lagoons.
- The presence of this species is causing some concern due to its ability to grow in colder waters and possibly Lake Tahoe proper.
Research & Coordination:
- Initial collaboration with Tahoe Regional Planning Agency and Tahoe Resource Conservation District.
- Initial experiments with bottom barriers.
- Comprehensive literature research on control methods.
- Informational consultations with Lahontan Regional Water Quality Control Board, Lake Tahoe Aquatic Invasive Species Coordinating Committee and others.
- Waste Discharge Requirement (WDR) Permit issued in 2014, necessitating Integrated Management Plan and Non-point Source Water Quality Management Plan.
Research & Collaboration:
- Education and outreach to homeowners, landscaping companies and other land owners for Non-point Source Plan.
- Independent Scientific Panel review of Integrated Management Plan.
- Fragment Control method evaluation including new boats, boat backup station.
- Alternative methods research and field study.
- Water quality monitoring and study.
- Collaboration with stakeholders in planning process, including the Lake Tahoe Water Suppliers Association, League to Save Lake Tahoe, Sierra Club, Tahoe Resource Conservation District, Tahoe Regional Planning Agency, Lahontan Regional Water Quality Control Board.
Implementation, Demonstration & Evaluation:
- Small-scale herbicide test followed by non-herbicide methods pending approval (2022).
- Non-herbicide combination methods evaluation pending funding (diver assisted pulling, broader bottom barrier use, UV Light test, Laminar Flow Aeration, Circulation system) 2017-2021.
- Long-term Integrated Management Plan (2020).
Control Methods Test (CMT)
- A 3-year long multi-treatment test to combat the spread of aquatic invasive plants in the Tahoe Keys Lagoon.
Water Quality in the Lagoons
There are several Water Quality Problems that the TKPOA has spent millions to address.
Aquatic Invasive Species (AIS)
AIS have taken over the keys lagoons
A few different species of AIS have taken root in the Tahoe Keys lagoons. The most dominant one is Eurasian milfoil that was first sighted the 1980s. Curlyleaf Pond weed was first detected in 2003 and has recently spread throughout most of the Keys Lagoons.
Blue Green Algae
The Tahoe Keys lagoons have seen cyanobacteria blooms since 2017. These blooms usually start during July or August. TKPOA responds to these blooms by working with regulatory agencies and taking precautionary steps to protect residents and visitors from any potentially harmful effects of the bloom. A bloom can occur under the right conditions (increased nutrients in the water from runoff in Lake Tahoe, high temperatures).
- Multi-billion dollar problem nation-wide
- Caused largely by phosphorous
- Click here to learn more
Overview of the Tahoe Keys Lagoons
The Tahoe Keys have 172 acres of waterways with 1,529 homes and townhouses along with commercial businesses. The waterways include the Lake Tallac Lagoon (a storm water collection basin for South Lake Tahoe), the West Lagoon, and the East Lagoon. Both the West and East lagoons have direct connections to Lake Tahoe via the West and East channels.
There are now 3 macrophyte species causing problems for boaters of the keys. These species are Eurasian watermilfoil (Myriophyllum spicatum), curlyleaf pondweed (Potamogeton crispus), and the native coontail (Ceratophyllum demursum). The species thrive during the summer when growing conditions are ideal. Every winter aquatic macrophytes die off and deposit a layer of detritus that decomposers break down into nutrients that fuel plant growth the following year. This excessive plant growth is a major cause for poor water quality in the Tahoe Keys lagoons. The TKPOA has been attempting to find a solution to this problem for decades.
Lahontan Regional Water Quality Control Board (LRWQCB) issued the TKPOA a Waste Discharge Requirements (WDRs) permit: Executive Order No. R6T-2014-0059. This specifies that the TKPOA must improve the control of aquatic invasive plants in the Tahoe Keys lagoons. The WDRs also state that the TKPOA must develop an Integrated Management Plan (IMP) for aquatic macrophytes and a Nonpoint Source Plan (NPS Plan) to improve water quality. The TKPOA voluntarily added Baseline Water Quality Program in 2016. The goal of the Baseline Water Quality Program is to establish an inventory for several water quality and sediment parameters. The baseline data will be used in future years to detect changes in water quality resulting from aquatic plant control methods implemented under the IMP and to monitor surface water input for the NPS Plan.
Property in and around the Tahoe Keys lagoons is controlled by multiple landowners including individual property owners, Tahoe Keys Property Owners Association, Tahoe Keys Beach and Harbor Association, Tahoe Keys Marina along with other commercial and governmental ownership. The TKPOA maintains the waterways for boating and other recreation. However, the ownership situation makes managing the waterways difficult as owners are not required to adapt to the TKPOA best management practices for the Integrated Management Plan (IMP).
The TKPOA has been working to control the plants in the lagoons by looking for long-term, integrative solutions for decades, working with a broad-range of scientific experts, associations and agencies to vet an exhaustive list of potential plant control measures while examining and evaluating new techniques and technologies as they arise. .
TKPOA is committed to solving the invasive plant problem and has so far spent $3,700,000 to manage the invasive plants and to develop improved methods. We're expected to spend another $2,500,000 by 2020. This funding comes from special assessments paid for by the property owners, along with grant funding and other private funding.
The 1,500 Tahoe Keys property owners consistently support invasive plant management strategies in and out of the water including: Voting for a special assessment to continue funding the invasive plant management program.
- Committing to Lake Friendly Landscaping and irrigation practices to protect water quality from nutrient runoff.
- Labeling all storm drains in Tahoe Keys to address and educate residents about nutrient runoff.
- The Water Quality Committee volunteers hundred of hours per year toward these efforts.
TKPOA has collaborated with the Tahoe Regional Planning Agency, the Tahoe Resource Conservation District and US Forest Service since 2011. We have also worked with the League to Save Lake Tahoe to implement ways to prevent plant fragment spread.