Diverse and dedicated. Our people help shape our future.

Nion McEvoy

Nion McEvoy

Owner, Chairman, and CEO

Nion McEvoy has a knack for bringing passionate people and projects together. McEvoy Ranch’s President since 2014, Nion worked previously in the business affairs departments of the William Morris Agency in Beverly Hills and Wescom Productions. A graduate of the University of California at Santa Cruz and the University of California’s Hastings College of the Law, Nion is also Chairman and CEO of Chronicle Books. He currently serves as Commissioner for the Smithsonian American Art Museum, and on the boards of the SF Film Society, the UCSF Foundation, and the San Francisco Museum of Modern Art. Through Petaluma Projects LLC, he has been involved with the films “Chasing Coral”, “The Fourth Estate”, and “Won’t You Be My Neighbor?”.

In between all the work, Nion is also a poet and art collector. His love of music is often intertwined with his responsibilities at McEvoy Ranch and Chronicle Books. He founded the McEvoy Foundation for the Arts, a non-profit arts exhibition space in San Francisco that is free to the public, to showcase his family’s extensive collection and complementary pieces on loan. Nion is a former meditation teacher, a drummer in two bands, and he has three grown children. You might say he’s anything but typical and that’s perfect.

Samantha Dorsey



A McEvoy Ranch veteran, Samantha Dorsey has been the General Manager since 2016. Given her tenure, Samantha is intimately familiar with every aspect of the property including our unique microclimates that provide a distinct terroir to our orchard groves, vines, and gardens. She also exhibits many of the core values that we cherish including passion, integrity, and curiosity.

After receiving her BA in Environmental Studies from Oberlin College in 2001, Samantha began her career with us. In the early years, she managed the Ranch’s olive tree nursery, propagating and selling thousands of olive trees that now thrive throughout the Western United States. In 2007, Samantha was promoted to Vineyard Manager and oversaw the initial release of McEvoy Ranch wine offerings. As her knowledge grew, so did her responsibilities. In 2013, she was elevated, once again, to Farming Manager giving her oversight of the entire property. This role focused her directly on our organic and sustainable certification requirements including those with the California Certified Organic Farmers, fiscal management, and supervision of a diverse crew.

As General Manager, Samantha is shepherding us into our next stage of growth. She continues to lead workshops on olive orchard management at the Ranch and shares her expertise regarding sustainable farming with other growers in many areas including California, Oregon, Arizona, Mexico, and New Zealand.

Samantha is fluent in Spanish and English and can often be found walking the grounds with her faithful four-legged Catahoula friend, Bluebell.

Byron Kosuge



Byron Kosuge joined McEvoy Ranch in August 2017 while the grapes were undergoing veraison. The timing was perfect as it allowed him to quickly get a grasp of our distinct Petaluma Gap microclimate.

A native of Davis, California, he caught the wine bug after delving into English and American Literature at UC Davis. Byron has extensive winemaking experience specializing in Pinot Noir, that most finicky of grapes, and Chardonnay. In addition to his own B. Kosuge brand, he has worked for several notable wineries including Saintsbury, Miura, Kingston Family Vineyards, and Small Vines Wines. His distinct wine style will build upon ours and he’s got a wicked sense of humor that fits right in with us! One of the things he likes best about making wine is that the process has a beginning, middle, and end. Each vintage is a slightly different story that unfolds slowly and, like a good book, requires diligence and patience to understand.

When he’s not running in a hundred different directions, Byron can be found trying to catch up on the piles of books that still clutter his house. Byron lives with his wife Mary in Napa.

Ria D’Aversa


Farming Manager

With more than a decade of horticulture, viticulture, and project management experience that spans New York, Vermont, San Francisco, Chianti in Italy, and Sonoma County, we love the depth that Ria D’Aversa brings to this position. A native of New Jersey with deep farming roots in Vermont, Ria has a Botany degree from the University of Vermont and a Masters from UC Davis in Horticulture/Agronomy with a Viticulture focus. She has always enjoyed working with her hands. In the beginning, it was with pastry dough as a chef-in-training in Florence. Lucky for us, she soon moved on to work harvest in Tuscany and the rest, as they say, is history.

Ria’s experience includes working with the California Academy of Sciences - a leader in promoting biodiversity on a global scale, the New York Botanical Gardens – in a conservation and research capacity, and with several wineries (in Italy and Northern California) working with both olive trees, olive oil production, and vineyard development. In her role as McEvoy Ranch Farming Manager, Ria works closely with Winemaking to ensure our strict certification standards are constantly met and that our orchards and vineyards deliver consistent quality fruit. Ria brings renewed energy toward our focus on a balanced agriculture ecosystem within our unique parcel of land.

Tri-lingual, Ria is fluent in Italian, Spanish, and English (and can swear in all three too!) An active member of the American Vineyard Foundation, she and her fiancé, a winemaker, live in Santa Rosa.

Ria D’Aversa



Jacquelyn Buchanan blends her enduring passion for artisanal, local, and sustainably grown foods with more than 20 years of experience as a chef and culinary educator. For Jacquelyn, the world of food, wine, and agriculture captured and continues to drive her ongoing curiosity. Guests at the Ranch will see this energy firsthand by attending one of our CHATS (our informal gatherings on a variety of topics), reading an in-depth topic on the Fresh Press Blog that Jacquelyn has curated, or trying one of her many recipes featuring seasonal items.

A professional chef, Jacquelyn cooked in some of the San Francisco Bay Area’s most distinctive restaurants, beginning with legendary chef Judy Rodgers at The Union Hotel (pre Zuni Café), the Hayes Street Grill, The General’s Daughter in Sonoma, and George Lucas’ Skywalker Ranch in Marin. Her background includes work at Laura Chenel’s famed cheese company and as the Julia Child Director of Culinary Programs at COPIA in Napa. She returned to her passion for teaching by revamping the Bauman College curriculum and Natural Chef Training Program.

A member of Les Dames d'Escoffier, Women Chefs, Chefs Collaborative, and the California Artisan Cheese Guild, we love the creative energy that Jacquelyn brings to the Ranch and her amazing taste buds. She lives in Petaluma, a stone’s throw away from the Ranch.

Maurizio Castelli


Consulting Winemaker & Agronomist

Dr. Maurizio Castelli, an agronomist and enologist originally from Pistoia, played an integral part in our creation and evolution as makers of exceptional extra virgin olive oil. As the story goes, Nan McEvoy called him to discuss the best Italian olive varieties to plant, and three days later, he was in Marin County advising her. The relationship continues today and it was a natural step when we began our foray into wine to rely on his expertise again.

A pioneer who helped to create such renowned wines as Col d'Orcia's Poggio al Vento Brunello di Montalcino Riserva, Mastrojanni's Brunello Schiena d'asino and Poderi Boscarelli's Vino Nobile, Castelli has more than 40 years of experience in winemaking and consulting all over the world, including at the famed Badia a Coltibuono in Tuscany. He travels to California several times a year to work at the ranch during the various stages of our olive oil and wine production, as well as to celebrate each harvest with us.

Nan McEvoy



Being regarded as a pioneer in her field was business as usual for Nan McEvoy. Her grandfather, Michael De Young, founded the San Francisco Chronicle in 1865 and Nan started there as a cub reporter, a rare position for a woman at the time. She worked her way up and eventually served as Chairwoman of the Board from 1981 to 1995. When a director's bylaw forced her into retirement at age 72, Nan set about doing what she does best—making things happen—and McEvoy Ranch was born. Always an activist with an adventurous spirit, she was an early member of the Peace Corps and John D. Rockefeller's Population Council. Nan was named Food Artisan of the Year by Bon Appetit in 2003.

Nan’s passing in March 2015 at age 95 reminded us all to live every moment to its full potential and to continually seek out new opportunities…even when it goes against conventional wisdom. Her vision and drive inspire us to be respectful of the natural beauty that surrounds us whilst curating our inner entrepreneur.