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from One Tam



Dear Friend,

As the end of the year approaches, we extend our gratitude to all One Tam supporters. Thanks to you, One Tam welcomed the return of in-person volunteer opportunities, organized immersive programs and field trips for middle and high school students, and led research and conservation efforts to protect Mt. Tam's biodiversity and more—read on for recent updates!

I’m excited to announce that a group of generous One Tam donors will match your end-of-year gift dollar for dollar up to $26,000, as long as it is received by December 31! Please consider making a special gift to One Tam this season while you can double your impact. Join us today.

Cailey Gibson

Associate Director, Individual Giving, One Tam

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One Tam Partners AND Canal Alliance to Connect Students to the Mountain

Canal Alliance University Prep youth hike with One Tam

Students from the Canal Alliance’s University Prep Program head out for a hike together in the Marin Headlands. Photo: Grecia Solis Pacheco / One Tam

After a hiatus during the COVID-19 pandemic, One Tam staff have again been facilitating field trips for youth from the Canal Alliance's University Prep program. The University Prep program prepares middle and high school-aged students to graduate ready for college, apply and enroll in college, and to succeed as college students. These monthly outings with One Tam complement the University Prep program by connecting youth to the public lands of the Mt. Tam area, providing space to build community and leadership skills, and building students' knowledge and appreciation of local ecology. Field trips include visits to Muir Woods and Lake Lagunitas, as well as other sites in Marin. We look forward to sharing more highlights!


Help Conserve Water This Winter

Phoenix Lake low water level

Phoenix lake before the October rains. Photo: Marin Water

Despite recent rains, California, including Marin, is still in a historic drought. Mt. Tam's reservoirs are still below where they should be for this time of year. While we don’t know what this winter will bring in terms of precipitation, we do know that rain patterns are becoming more erratic and unpredictable. We could have another dry winter. To support water conservation, Marin Water has issued new water rules that went into effect December 1—learn more and please help: 


New Funding for Evolving Shorelines

Bay Trail in Marin credit WRT

Newly resurfaced Bay Trail with the approaching 6.7 foot high tide on November 5. Photo: WRT

On October 15, the Governing Board of the San Francisco Bay Restoration Authority approved grant funding for the Evolving Shorelines project at Bothin Marsh. This exciting development reinforces that habitat enhancement and Bay Trail improvements at Bothin are priorities for the Bay Area. This additional funding leverages continued support from Marin County Measure A and One Tam donors to take the next steps in project planning.

When October's heavy rains and high tides caused major flooding in Marin City and Mill Valley, we captured data on sediment flows in Coyote Creek. Preliminary results indicate that substantial amounts of sediment are coming through the watershed. We are updating our computer modeling to study how this nourishing sediment could be better directed and captured to help the marsh accrete, or build elevation. Understanding sediment dynamics will be a key factor influencing the designs for improving the marsh’s resilience to sea level rise.

With the multi-use, “Ring the Marsh” path concept identified as the favored approach for the project, we now need to take a closer look at where a realigned Bay Trail could be located. This month, our engineering and design team began surveying existing infrastructure and boundaries along the perimeter of Bothin Marsh. Later, we will explore the subsurface conditions to understand the location and character of bedrock, bay mud, fill, or other soils underground. These next steps will be critical to understanding how and where we could potentially build a new trail.

Stay tuned to this newsletter for updates coming next spring. For now, visit to learn more about Evolving Shorelines. 


In Search of Thoroughwort

Thoroughwort survey 2021 map - One Tam

The purple line represents the survey area, while the yellow squares represent new thoroughwort observations. In addition to the hiking portion of the survey, the One Tam team surveyed Panoramic Highway via car which can also be seen on this map. Figure: One Tam

Keeping invasive plants at bay is a key way that One Tam supports the health of Mt. Tam. But first, you have to find them. The One Tam Conservation Management Team recently set out in search of thoroughwort (Ageratina adenophora), which we’re working to keep from the upper mountain. 

Thoroughwort is found in areas with year-round moisture. It produces abundant seed that is widely dispersed by wind, water, soil movement, and by sticking to animals as they brush against it. Once established, it forms thickets and outcompetes native vegetation. Thoroughwort is heavily concentrated in the drainages on the southwestern slopes of the mountain, where it receives ample moisture from fog drip, yet still uncommon on the north side of the mountain. 

The team needed to find out where the leading edge of thoroughwort lay. They identified its potential habitat using the Calflora Database and created a survey plan around those locations, focusing on the drainages below Ridgecrest Boulevard and near Bootjack Campground. Over five days, the team hiked across the length of the Ridgecrest grassland, dropping into rarely visited drainages. They quickly learned to identify which drainages were likely to have thoroughwort based on the plant community and soil moisture. If they saw chain fern or elk clover, for example, it was an indicator that thoroughwort may be nearby.

The team not only mapped the leading edge and removed smaller plants along the way, but gained a better understanding of where to look for thoroughwort in future surveys. The data they collected will inform treatment in 2022.


Tamalpais Bee Lab Winter Dates ANNOUNCED

Tamalpais Bee Lab event

Volunteers learn about wild bees with One Tam Community Science Program Assistant Sara Leon Guerrero at a Tamalpais Bee Lab Event earlier this year. Photo: Lisette Arellano / One Tam

Many thanks to the volunteers who joined One Tam’s effort to learn more about Mt. Tam’s wild bees and other pollinators this year! We are happy to announce more Tamalpais Bee Lab volunteer dates coming up in the new year—sign up at the link below! 

Why study bees? Before embarking on this study, we didn’t know much about our region’s wild pollinators, or how our local populations were doing. Pollinators were identified as a key knowledge gap during One Tam’s initial Peak Health effort in 2016, where we worked to understand the health of Mt. Tam. Indicators of health, like pollinators, will be tracked over time, so we can keep a pulse on how they are doing and inform our stewardship in the region.

We need to collect baseline data about bees in order to understand change. For example, we didn’t know that that there are an estimated 400+ bee species on Mt. Tam until we did this study! We have a number of other questions we are looking to answer with this work, and with your help, we’ll be able to! 

Volunteers are a critical part of this work, and The Tamalpais Bee Lab offers an opportunity to connect with the One Tam community of staff and volunteers, gain skills in scientific collections management and insect identification, and develop an appreciation for these critical pollinators.

Learn more about the Tamalpais Bee Lab and register to volunteer >>


Meet a Bee!

Bombus californicus. Image by One Tam

Bombus californicus, California bumble bee. Photo: Kris Fleming / One Tam


Pleased to meet you! I’m Bombus californicus, also known as the California bumble bee.

You'll find me flying February to October throughout much of the United States in grasslands, farms, urban parks and gardens. You might see me visiting California poppies, thistles, and mints. Like other bumble bee species, I live in a colony with a queen, workers, and males. Unlike our honey bee cousins, whose colonies persist for multiple years with the same queen, bumble bee colonies survive for one year with new queens founding their own colonies each spring.

I can look different throughout my range, but in California I usually have a black body with two broad yellow bands near my head and the end of my abdomen. I look very similar to the yellow-faced bumble bee, B. vosnesenskii, but you can tell us apart because they have a yellow face and I have a black one.

This Bombus californicus worker was collected during the initial 2017 Tamalpais Bee Lab survey. In addition to pinning and identifying, macrophotography is another important way of documenting the bee species that we are observing on Mt. Tam. These up-close images reveal more about the incredible complexity, diversity, and beauty of the region’s bees than may usually meet the eye. It will also allow us to share more about these incredible creatures more broadly. Big thanks to Kris Fleming, who interned with One Tam over the summer and completed a stunning series of these photos as part of his internship. 

Learn why we're conducting this study and meet more amazing bees in future newsletters!


About Us

California newt at Lake Lagunitas, Mt. Tam

A California newt at Lake Lagunitas on Mt. Tam 

One Tam works to ensure a healthy, vibrant and diverse landscape for our beloved and iconic Mt. Tam. We are the community-supported partnership of Mt. Tam’s land agencies and managers.

One Team leads programs that care for our mountain, inspire our next generation of land stewards and strengthen our local community. We invite you to join us.

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Going Further, Together

One Tam brings together inspired community members with its five partners to support the long-term stewardship of Mt. Tam.
One Tam Partner Logos: National Park Service, CA State Parks, Golden Gate National Parks Conservancy, Marin Municipal Water District, and Marin County Parks

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