Sierra Club members from San Francisco and the Bay Area could make reservations at the Clair Tappaan Lodge by visiting 1050 Mills Tower at 220 Bush Street, San Francisco, which provided chartered bus trips. This was a national office from 1931 to 1975. The Mills Tower location is only 3,400 feet from the once residence of Melvin Belli, who lived at 1228 Montgomery Street, which would receive a letter from the Zodiac Killer on December 20th 1969 (thanks to Jibberjabber for this). The Clair Tappaan Lodge (15 miles west of Lake Tahoe), was (and is) the predominant "Sierra Club" in this region, leaving little doubt that the Zodiac Killer (or hoaxer) was referencing this Sierra Club when affixing this newspaper cutting to the Pines postcard on March 22nd 1971.
On October 28th 1977, the "Press of Atlantic City" newspaper ran an article about the Pinelands Environmental Council in respect to the Pine Barrens, stretching over the seven counties of New Jersey. It read "As the official guardian of the pines, I'm afraid we lost valuable time". The Sierra Club had an active interest in the preservation of the Pine Barrens during the relevant period to both the Pines postcard and Mary Pilker Christmas card. On the left is one example from 1971. Could the Zodiac Killer have been suggesting that Donna Lass being buried amongst the pines, was somehow looking over and protecting them in the afterlife?
The Zodiac Killer, having a voracious appetite for trawling the newspaper columns, would very likely have been aware of the Clair Tappaan Lodge Sierra Club and its activities, including its involvement in caring for the environment. The Sierra Club meetings and trips were heavily featured in the Bay Area newspapers (and vicinity) on a continuous basis. Various examples have been presented below. Some people will attempt to downplay the Sierra Club pasting on the Pines postcard as the Clair Tappaan Lodge, explaining that we cannot be sure this was the intended "Sierra Club". While we cannot be certain, the overwhelming evidence suggests that this was the location insinuated by the designer of the postcard, bearing in mind its sender included an advertisement of "Forest Pines at Incline" Village. So, was the Zodiac Killer aware of the Clair Tappaan Lodge through the newspapers, through visiting the Donner Ski Ranch as a tourist/hiker, or was he a member of the Sierra Club in the Bay Area?
However, caution must be applied to any analysis achieved with hindsight (in this instance, the approximate location of Donna Lass' remains). Credit to Howard Davis for providing me with the Mary Pilker Christmas card.
FURTHER READING: THE BOISE CASCADE CHRISTMAS CARD TO MARY PILKER IN 1974?