Lady of the Lake: More on preventing invasive mussel introductions, part two
- Angela De Palma-Dow
- Posted On
Dear Lady of The Lake,
I am an avid fisherman and moved to Lake County to enjoy my retirement fishing on Clear Lake. I recently purchased a bass boat and had to purchase a Lake County quagga mussel sticker. I don’t know much about these mussels or what would happen if they got into our lake. Can you provide some information so I can make sure we are doing all we can to protect Clear Lake?
Thanks,
Frank the fisherman
Dear Fisherman Frank,
Again, thank you for this question. As you recall, I answered part of your question in part 1 in my column from Sunday July 16, 2023. Readers can visit Preventing invasive mussels, part one.
Like in part one, this column is focused on invasive mussels, or specifically Quagga (Dreissena rostriformis bugensis) and Zebra (Dreissena polymorpha) mussels, which are both freshwater mussels in the Dreissenidae family. I will refer to these mussels as invasive dreissenid mussels.
Today, in part two, I will describe our prevention program, why it's needed, how it works and how we can all help keep invasive mussels out of Clear Lake. Lastly, we will talk about the County of Lake’s current plans for a rapid response, control, and containment plan. There is even a way for the public — you! — to be involved in the planning process.
If you are unsure of what defines an invasive species, please revisit part one, as I describe in detail what is considered an invasive species, and the difference between them and a desired non-native, such as black bass.
In part one we discussed where invasive mussels originated, how they came to North America and the devastating impacts they could have if introduced into Clear Lake or other Lake County water bodies.
The impacts of an invasive dreissenid mussels introduction would be horrific, destroying the local lake-based economy and impacting the lake ecology and food web in unpredictable ways. The probability of a mussel introduction into Clear Lake is high, due to the favorable environmental conditions of Clear Lake waters and the high use of the lake by visiting water users, recreationalists and fishers.
High-risk probability for invasion
The specific favorable environmental water conditions for invasive dreissenid mussels include waters with a high pH (up to 9.5), calcium concentration above 12 mg/L, total hardness between 100-420 mg/L of CaCo3, and a salinity below 12 ppm. Water quality monitoring conducted by Lake County Water Resources reveal that Clear Lake, and surrounding water bodies, do contain these specific water conditions.
These conditions are important to acknowledge because if an invasive mussel was to become introduced into the lake, the environment here is suitable for them to be not only comfortable, but to thrive. We know that the local environmental condition is an important part of what makes a successful introduction grow to an established infestation.
The second factor that makes Lake County extremely susceptible to an introduction is that Clear Lake, the main attraction for water users in Lake County, is huge, and has over 120 miles of shoreline where boats can access the water.
According to the Lake County Water Resources, there are also over 750 public and private access ramps and points around the Clear Lake shoreline. About 15 of those access points are public and only about 11 of those access points are regularly monitored by ramp monitors and prevention program staff.
In addition, Clear Lake is a fishing tournament destination, for prize game fish such as bass, crappie, and catfish. In fact, in 2020, Clear Lake was rated the number #1 Bass fishing lake of the decade by Bassmaster magazine. The boats that participate in these large tournaments come from all over the United States throughout the year, including from mussel-infested states, counties, and water bodies.
The ease of access by boat to the lake, combined with the high number of boating visitors per year from potentially infested lakes, combined with the favorable water conditions means that Clear Lake is at high-risk for an invasive dreissenid mussel introduction.
Due to the high-risk scenario of destruction that would occur should there be an aquatic invasive mussel introduction into Clear Lake, the County established a robust prevention program to stop an invasive dreissenid mussel introduction from occurring in the first place.
It’s the law!
There is a county ordinance, Chapter 15 Article 9, that requires all water vessels be screened for invasive mussels before being able to legally launch in Lake County water bodies.
In addition to Clear Lake, the ordinance provides legal coverage county-wide, specifically, according to the County of Lake Invasive Mussel Prevention Plan (last updated in 2019), that outlines the mechanisms for implementing and enforcing the ordinance, “The purpose of this program is to prevent the introduction and establishment of invasive mussels in Lake County water bodies, including Clear Lake, Indian Valley Reservoir, Blue Lakes, Hidden Valley Lake, Highland Springs Reservoir, and Lake Pillsbury”.
The prevention program is described in detail on the Lake County Mussel website.
Failure to comply with the ordinance could lead a boater (and boat owner, should the operator be a different party) responsible for a hefty $1000 fine, at maximum. Minimum citations start at $100. In contrast, the cost of compliance in the program is easy, fast, and affordable.
Water vessel screening, inspections and decontamination
I commonly receive and hear comments from local boaters that their boat never gets “inspected” by prevention program staff, yet they still are required to purchase a Lake County Mussel Sticker.
The Lake County mussel sticker indicates that a vessel has gone through a screening process and been determined to be safe, and uninfested with invasive mussels - compared to the State Mussel Sticker which has no screening process involved.
The Lake County mussel sticker, both for resident and visitor boats, is different from the State of California DMV mussel sticker. As its name implies, the Lake County Mussel sticker is specific and unique to Lake County, and must be displayed on all boats and vessels that are launching (or within 50 feet of a waterbody) in Lake County water bodies.
The State Mussel sticker is required for all vessels registered in the state but allows boats to launch and load from any water body — even those that are infested with invasive dressenid mussels in Southern California such as Havasu, Pyramid and Piru Lakes.
The purpose of the State Mussel Sticker is to raise awareness and revenue to support a fund that can be used to implement state-wide aquatic invasive species programs and to prevent spread of mussels, and other dangerous invasive aquatic organisms, from impacting water ways throughout the state.
Some of the grants the County of Lake receives to implement the invasive mussel prevention program are sourced from this state sticker fund and administered through the California State Parks Division of Boating and Waterways.
Preventing the spread of invasive mussels one boat at a time
The Lake County invasive dreissenid mussel prevention program is based on a risk assessment screening process that determines and categorizes a boat is at low, medium, or high risk for moving invasive dreissenid mussels into and around Lake County.
The prevention program is administered through the use of Lake County-specific stickers that indicate if a boat has passed the risk assessment screening or has been determined to be cleaned, drained, dried. A boat that passes the screening process will be allowed to display a mussel sticker.
You can test your knowledge of the current Invasive Mussel Prevention program by taking this quiz.
Screenings are conducted by knowledgeable and trained County staff, like ramp monitors, and trained commercial or business employees at locations that sell mussel stickers, called screeners or vendors. A list and map of screening locations can be found online here.
First, residential boats that “live” or stay within Lake County, that do not travel outside the County, are considered very low risk. Meaning that they are basically guaranteed to not be moving invasive dreissenid mussels, as none of the Lake County water bodies, or neighboring counties, are infested with mussels.
These low risk boats can be affixed with a Lake County mussel sticker without being inspected or decontaminated — because they don’t have anything to be inspected or decontaminated for, since they don’t travel around and there is essentially no risk of them moving mussels.
Residential boats can get a Lake County mussel sticker valid for an entire calendar year and come in a set of three. These stickers usually display the year and are appended on both sides of the bow, adjacent to the “CF” registration numbers, and one sticker adheres to the back of the trailer. The trailer sticker purpose is to communicate to program staff monitoring the parking lots that while the boat is in the water, the boat -and boater- are still compliant with the sticker program.
Resident boats have to be registered in Lake County, and have to show proof of this registration, when they are purchasing stickers from a certified screener or vendor. Stickers are $20 for residents for a single calendar year and $20 per visitor for a calendar month. When stickers are purchased, boat owners / operators sign a form stating that they will get their boat rescreened should they take it out of County at any time.
The same form designates the boat owner and operator financially responsible should they be the ones found to move invasive dreissenid mussels into Lake County without getting their boat rescreened or inspected.
Visitor boats, that were previously in a non-infested water body, are also able to purchase and display a Lake County mussel sticker without an inspection. Program staff, at ramps, and at selected vendor locations, use handheld portable digital tablets and the Western Inspection Database (or WID) to check and confirm the information provided on screening forms is true and accurate.
The tables are connected to a large database managed by the Colorado State Parks Invasive Mussel team. The database connects lake managers and prevention programs across the western United States, to identify boats that are at high risk for moving invasive mussels.
Boats that leave infested water bodies will appear in the database when they try to get screened in Lake County. If the period between leaving an infested water body and entering Lake County is less than 30 days, then the database screen will flash red, and recommend an inspection or decontamination, when that boat’s information is scanned into the database.
Boats that don’t pass a screening, including visitor boats that come from counties or water bodies that are known to be infested with dreissenid mussels, are required to get their boat inspected. An inspection is performed for free by a County employee that is specifically trained to find small, tiny mussels or unidentified water on a vessel.
Inspectors are thorough, and will sometimes climb into the boat and search live wells or ballast compartments, look around engine compartments or along water outflow ports and intakes. The inspectors are looking for the attached adult form of invasive dreissenid mussels, but also the juvenile form which can only survive in standing water.
The juvenile form of invasive dreissenid mussels are very small microscopic free-floating organisms, called veligers, that can survive in any small pocket of cool water on a boat, in a bilge, or live well. If an inspector finds any wet area or collection of water on or in a boat and it's known that the boat was last in an mussel-infested lake or county within the last month, the boat will be considered high risk and assumed to be positive for invasive mussels, and will have failed an inspection.
If a boat fails an inspection, it will then be decontaminated by County staff. The decontamination procedure is also free, and can take between 20 minutes and 2 hours depending on the complexity of the boat.
Proper decontamination includes washing the outside of the boat and trailer, and any inner ports, compartments, ballast tanks, and intakes with 120 F degree hot water from a pressure washer.
120 degree hot water has been shown to cause mortality in both adults and juvenile invasive dreissenid mussels. While other states allow chemical decontamination, such as the use of Cleaner 409, bleach/chlorine, or specialty products like Vikron, the State of California does not recognize these as suitable decontamination methods and only approves use of 120 / 140 degree hot water.
Once a boat is decontaminated, and determined to be clean and clear of any potential adult or juvenile invasive dreissenid mussels, then the boat owner operator can safely purchase a mussel sticker for their boat and are free to launch unlimited times in Lake County until they cross back over the County line.
Mussel stickers work!
The sticker works because it communicates to the community that the boat displaying that sticker has successfully passed the boat screening-inspection-decontamination process and associated procedures and is safe for boating in Lake County. Without a sticker, no one would know if that boat was safe, has been screened, inspected, or cleaned.
Additionally, the mussels stickers are a unique financial resource for the local economy. When they are sold by participating vendor screeners, the business conducting the screening receives a portion of that sticker sale cost. For some busy shops, the money generated from mussel sticker sales are significant and can pay for utilities, insurances, or extra staff help during the busy season.
The rest of the sticker proceeds go to the County of Lake Water Resources department and are 100% consumed back into the costs of administering the invasive mussel prevention program.
Informational flier identifying the distribution of revenues from the Lake County Mussel Sticker Program. Currently stickers are only $20 for residents and visitors.
If mussels become introduced into Clear Lake, or Lake County, the prevention program dissipates along with the sticker program. This could mean a significant drop in revenue for local businesses like bait and tackle stores, hardware stores, and individual screeners.
To learn more about the current prevention program, you can visit the County of Lake Invasive Mussel web page at www.nomussels.com.
Planning for an introduction
While focus and investment into the prevention program is the ultimate goal and strategy, there is a chance that mussels could be discovered in Clear Lake or other Lake County Water bodies.
The County of Lake Water Resources staff are preparing for this occurrence, to ensure that the impact to economy and ecology are minimized as much as possible. Water Resources secured a 2021 US Fish and Wildlife grant to hire a specialized firm to facilitate the development of an Invasive Mussel Response and Containment Transition Plan for Clear Lake (“the plan”).
The grant and plan have a new, corresponding website that is a great source for literature, links, ways to get involved, and updates on the plan status, progress, and components. You can access the plan website here.
The purpose of the plan is to outline the steps needed to follow for when or if an invasive mussel becomes introduced into Clear Lake. Depending on the location and type of introduction, there is a chance that a chemical or biological agent could be applied to kill off any introduced mussels before their spread throughout the lake. The plan identifies these potential products and how they could get approved for application if needed.
If spread throughout the lake has already occurred, then the plan outlines how the County and partners can implement a containment strategy to prevent spread of mussels from Clear Lake to regional water bodies that would, assumingly, remain mussel-free at this point within this theoretical scenario.
The website, and plan, even includes lessons learned and outcomes from a “Response Exercise” that included participation from local and state agencies and emergency personnel working through example scenarios where mussels were introduced into Clear Lake and responses needed to be developed.
The second part of the plan, called a “Containment Transition Plan”, like it sounds, focuses on preventing mussels from leaving Lake County water bodies and infecting other regional water bodies. Part of the concern driving the need for a containment plan, is that if mussels are discovered in Clear Lake, the state could limit or eliminate fishing tournaments or boating activity completely. This was the course of action that closed San Justo Reservoir, in San Benito County, once zebra mussels were discovered in that water body. That county is still living with the impacts of that closure.
This is obviously the worst case scenario, but if the State wanted to prevent any chance of mussels moving from Clear Lake, to regional water bodies or throughout the state, then eliminating that vector (i.e. the boats!) would prevent any potential for movement. And because Clear Lake is technically a public state-owned lake, they would have the ability to impose those restrictions.
You can imagine how such fishing restrictions would damage the Lake County economy that is mostly lake and water based. Therefore, developing a containment transition plan now, and including state input and direction, is being proactive in identifying alternative actions that could prevent short and long term financially devastating outcomes.
The Rapid Response and Containment Transition Plan is currently in final draft form, but community feedback is still welcome and needed. The firm writing the plan held two public forums to gain community, business, commercial, and agency input. One of the forums was featured on a County of Lake Water Resources Water Quality Wednesdays and posed the question about how an invasive mussel introduction would impact the community and businesses.
There is still time to provide your comments and review the draft version of this plan. This is especially important if you or your business relies on Clear Lake and is dependent on water based activities.
You can access the plan draft here and submit comments on the same page.
It’s important to gather and include community input because an invasive dreissenid mussel introduction would have significant impacts that would trickle throughout the community, and anything that can be done now to lessen or remove those impacts should be pursued and prioritized.
Sincerely,
Lady of the Lake
Angela De Palma-Dow is a limnologist (limnology = study of fresh inland waters) who lives and works in Lake County. Born in Northern California, she has a Master of Science from Michigan State University. She is a Certified Lake Manager from the North American Lake Management Society, or NALMS, and she is the current president/chair of the California chapter of the Society for Freshwater Science. She can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..
The County of Lake Water Resources Department wants to know what you know about invasive mussels! Take this 2-minute survey and get entered to win a FREE 2024 resident or visitor sticker for your boat (a $20 value!). You can access the survey from a computer, tablet, or smartphone at this link: https://forms.gle/5YRq5hPcAdR8NBm56.