Two ranches in Marshall and Tomales became the first to amend their easements with the Marin Agricultural Land Trust to actively require commercial agricultural use in perpetuity, a key part of sustaining ranching and farming in West Marin. Until 2011, MALT purchased easements prohibiting subdivisions and other types of development, but it did not expressly require the practice of agriculture on preserved lands. For the past few years, new easements have included the additional restriction, but the Poncia Ranch and the Barinaga Ranches are the first to update old agreements. The new requirement is legally referred to as an “affirmative agricultural covenant,” and MALT says it is necessary to curb the emerging trend of estate development in places like West Marin, which provides picturesque rolling hills and an easy drive to the city for the Bay Area’s wealthy. (MALT also said it is the first land trust in the country that offers a comprehensive mandatory agricultural use program.) The retroactive amendment is voluntary, but provides additional compensation; MALT declined to disclose the purchase price of the amendment. Al and Cathie Poncia, who sold the original development rights to the 269-acre ranch in 1992, are the third generation to steward the Poncia family’s land in Tomales. There, the couple grazes about 100 ewes and leases land for an organic dairy with 200 cows operated by Moreda Family Farms. “If my family ever decides to, or is forced to sell the land, it would ensure the continuance of some form of productive agriculture on this property,” Mr. Poncia said in a press release. Because the amendment diminishes the value of the land, the ranch would also be more affordable to future ranchers if it were sold. The Poncia family, including Al’s son Loren, also runs two other nearby ranches; MALT purchased easements on one in the 1990s and the other in 2013. One ranch, however—the 823-acre Barinaga Ranch overlooking Tomales Bay, which Marcia Barinaga and Corey Goodman bought in 2001 and where Ms. Barinaga milks sheep for her award-winning Basque-style cheese—gifted the value of the easement to the nonprofit.