May 2024 | Richard Panuschka
Update on the New Zealand mudsnail (NZMS) infestation!
Background
Many of you may recall news of a new invasive species detected in Lake Tahoe last summer. I would like to provide you with an update on this species as well as provide some guidance on how to prevent its further spread.
Towards the end of last summer, divers with Marine Taxonomic Services, ltd. (the company that I work for) discovered these small snails along the shores of South Lake Tahoe. These snails range in size from less than 1mm (1/32in.) to about 5mm (5/32in.). Usually, they are the same size as the average grain of sand on our beaches. This makes them highly transportable and very difficult to notice.
The Problem
This species is problematic for freshwater ecosystems because they feed on native plant and animal detritus, algae, and diatoms (single-celled algae). Many of the impacted native species contribute to the notorious clarity of Lake Tahoe’s water.
The species has been detected throughout Lake Tahoe’s south shore with the highest concentrations in a 3-mile-wide patch between Pope and Reagan beaches (AKA the Tahoe Keys and Upper Truckee Marsh). However, NZMS have been detected as far west as Kiva Beach and as far east as Elks Point and to depths down to 30m (98ft.). Furthermore, it is highly likely that this infestation has spread since the most recent surveys in October 2023.
So what can we do about this?
The Tahoe Regional Planning Agency (TRPA), which is the lead response agency, has provided guidance to help prevent the further spread of this species (https://www.trpa.gov/new-zealand-mudsnail/). Here are the “actions for boaters” from TRPA:
Prevent the spread of New Zealand mudsnails around Lake Tahoe.
- Temporarily avoid boating in areas of Lake Tahoe known to have them. View the map here.
- Do not fill any onboard systems (ballasts, fish wells, etc.) in these areas.
- Spill Where You Fill. Whenever filling raw water in boat systems, plan to discharge it in the same area you picked it up.
When hauling out of Lake Tahoe, avoid taking aquatic invasive species with you.
- Drain all water from your vessel away from surface water and storm drains.
- Pull all plugs and sea strainers; drain ballast tanks and fish wells or other onboard systems.
- Ask launch facility staff for the appropriate location to drain.
Clean your anchor, hull and trailer of dirt, vegetation and debris and dispose of it in the trash.
- New Zealand mudsnails can easily go unseen in mud and vegetation. Remove and dispose of it.
Clean any sea strainers and flush your raw water systems (engine, a/c, generators, fish wells, ballasts, etc.) to make sure mudsnails aren’t present.
- Visit an inspection station (summer) or schedule a decontamination (winter) if you’d like to be decontaminated.
Dry your vessel for 5 days or more before launching again.
- New Zealand mudsnails are tiny and tenacious. To make sure anything on your boat is dead, dry your boat for 5 days or more.
As far as SLTWYC sanctioned activities (e.g. races and cruise-outs) are concerned, we will abide by the club’s purpose to “protect the environment” and “prevent pollution of recreation waters”. Therefore, any club equipment deployed in the lake (such as temporary or seasonal race marks) will be decontaminated upon removal from- or relocation within Lake Tahoe’s waters. All ground tackle will be collected into buckets/trash cans and treated with bleach-water to sanitize them. Additionally, boat anchors should also be sanitized with bleach-water as ground tackle is retrieved.
Since the area around the USCG’s “O” mark (where all our races start and finish) is a known hotspot for NZMS, additional care to prevent further spread will be taken. The Club will provide a containment bucket for the “Pumpkin” and Race Committee will diligently sanitize ground tackle in this area.
I am keenly aware of the inconvenience this creates for anyone boating in South Shore, but I sincerely hope that all of you take these recommendations seriously and make whatever reasonable efforts you can to reduce the further spread of invasive species throughout Lake Tahoe.
Please feel free to reach out to me with any further questions, comments, or concerns regarding invasive species in and around Lake Tahoe.
Richard Panuschka
Commodore
South Lake Tahoe Windjammers Yacht Club
