Drought, community support help save Lake Tahoe shore plant

The Tahoe yellow cress, which grows only along Lake Tahoe’s sandy shoreline, is no longer a candidate for the Endangered Species Act list.
The Tahoe yellow cress, which grows only along Lake Tahoe’s sandy shoreline, is no longer a candidate for the Endangered Species Act list. U.S. Fish and Wildlife Service

California’s lengthy drought, with all the havoc it has wreaked, has helped save the Tahoe yellow cress, a plant that grows only on the shores of Lake Tahoe.

It was a successful, local 15-year conservation effort to protect the plant and its habitat that led to the U.S. Fish and Wildlife Service’s announcement Wednesday that it has been removed as a candidate for protection under the Endangered Species Act.

The plant had been on the candidate list from 1980 to 1996, when it was removed for three years, then returned to the list in 1999, after which an extensive conservation effort began.

Wednesday’s decision was made after an analysis showed a significant reduction in habitat threats that had posed a risk to the health and persistence of the species, said Dan Hottle, a spokesman for the Wildlife Service.

During the most recent on-the-ground survey in 2014, biologists found the rare plant thriving at 36 of the 49 habitat sites they studied.

The Tahoe yellow cress (formally Rorippa subumbellata), a low-growing, flowering perennial plant in the mustard family, thrives only on the sandy beaches and dunes at the ever-changing margin of the lake.

The drought has helped by lowering the lake level and creating greatly enlarged beaches that, in addition to providing more habitat for the plant, give people using the beaches more space to avoid trampling it.

But while the drought has undoubtedly provided more habitat, “we’re not counting on that in having made our decision,” said Ted Koch, supervisor of the federal Fish and Wildlife Service’s Reno office, who recommended that the agency remove it from the candidate list.

“We hope the drought won’t be with us forever,” he said. “If the lake gets high again, there will be less habitat but still habitat.”

Rather, he said, the plant’s future has been ensured by a large group of lakefront homeowners associations and conservation groups, including California, Nevada and federal agencies, that have worked on protecting it and its ecosystem for many years.

“The purpose of the Endangered Species Act is to conserve ecosystems, and what we’ve found at Tahoe is that people share the same goal and have already acted to protect the ecosystem upon which the Tahoe yellow cress relies without having to list the species under the act. The best way to ensure conservation of a species is to support local leadership, and local leadership is what we have here. If the people in whose backyards the plant occurs care about protecting it, that’s the best assurance of long-term conservation.”

Once a plant is assigned to the endangered species list, Koch said, “it’s very rare to get taken off.” Plants are removed more often from the candidate list, he said, “but it’s still uncommon.”

The Tahoe yellow cress has been in trouble before.

The Wildlife Service declared it a candidate species for protection under the Endangered Species Act in 1980, but removed it from the list in 1996 when a period of lower lake elevations exposed its crucial, sandy habitat and increased its population estimates.

But in 1999, the service returned it to candidate status because years of higher lake levels had inundated its habitat, resurrecting concerns for the plant’s limited distribution, small population sizes and the inability to adequately control human impacts around the shore.

It was at this point that a large group composed of California, Nevada and federal land managers, regulatory agencies, conservation organizations and lakefront property owner groups formed.

Studying the history of the plant and compiling survey data increased the group’s understanding of the species’ population dynamics and its conservation needs.

From that information, they developed a comprehensive conservation strategy for the cress, finalized in 2002. In January 2003, they signed a memorandum of understanding to cooperatively implement the strategy for 10 years and renewed it in 2013 for another 10 years.

An updated, revised conservation strategy that reflects on actions taken in the past decade and incorporates continued conservation opportunities for the species is expected to be completed by the group within the next few months.

While much of the plant’s habitat has been fenced and signed, it is still in need of the public’s protection, according to the Active Management Working Group.

This group conducts an annual survey of the cress, maintains its enclosures on public beaches and educates lakeshore homeowners on ways to protect it on their property.

Its website tells people how to help the effort: Avoid vegetated areas, especially near creek mouths; maintain control of your pets; launch and beach boats away from the plants; do not enter fenced areas; and “spread the word.”