Report: Lake Tahoe faces major challenges due to climate change

The Lake Tahoe Basin saw continued environmental improvement over the last four years, but faces major challenges from climate change, according to a draft 2015 Threshold Evaluation Report released by the Tahoe Regional Planning Agency (TRPA).

The report offers a detailed assessment of the health of Lake Tahoe and its treasured natural environment as indicated by 178 threshold standards in nine categories: Air quality, water quality, soil conservation, vegetation, fisheries, wildlife, scenic resources, noise, and recreation.

TRPA leads the development of a threshold evaluation report every four years to examine the health of Lake Tahoe’s environment and help inform future program and policy decisions.

More than 60 people from 25 organizations contributed data, time, or analysis to the 2015 Threshold Evaluation Report. This report also marks the second evaluation to undergo an independent scientific peer review. Fifteen scientists examined the report’s findings, analysis, and conclusions and found them to be sound, and offered suggestions to improve the threshold standards and their monitoring and evaluation.

The 2015 evaluation was able to make status determinations for 110 of the 178 threshold standards. It found 77 of the standards to be in attainment, either at or better than target or considerably better than target. That’s up from 58 standards found to be in attainment by the 2011 evaluation.

Only two threshold standards—cushion plant communities on Freel Peak and open water productivity (algal growth)—were found to be in a declining trend compared to the last threshold evaluation.

The 2015 threshold evaluation contains a new analysis of Lake Tahoe’s streams. It found that pollution from non-urban upland streams is decreasing as the 500-square-mile watershed recovers from the historic impacts of grazing, logging, and other activities. This improvement is critical in the ongoing work to restore Lake Tahoe’s famous water clarity, which is projected to take several decades.

“This threshold evaluation shows we are continuing to make progress in conserving and restoring Lake Tahoe’s environment and improving recreation opportunities for people to enjoy this national treasure for generations to come. It also flags important areas needing further, focused attention,” said Joanne S. Marchetta, executive director of TRPA.

“It identifies future research needs and also lays out a framework to update our threshold standards to make sure they are giving us the information we need to make our programs, projects, and policies as effective as possible. This is especially important in light of the changing climate that threatens to impact everything from water clarity and nearshore water quality to forest health and recreation opportunities at Lake Tahoe.”

Updating the threshold standards is one of TRPA’s top strategic initiatives, along with other initiatives focused on forest health, invasive species, shoreline policies, and improving the Lake Tahoe Region’s development rights system to help accelerate the transfer of development out of outlying and sensitive areas and into town centers.

Most of the threshold standards have not been updated since they were adopted in the 1980s with the first Regional Plan. The update initiative, undertaken with the Bi-State Tahoe Science Advisory Council and many other partners in the Lake Tahoe Basin, will focus on making sure standards are measurable, scientifically sound, and provide the information needed to assess Lake Tahoe’s environmental health and ensure programs and projects are as effective as possible.

The draft 2015 Threshold Evaluation Report is available online at http://www.trpa.org/regional-plan/threshold-evaluation/. The TRPA Governing Board is scheduled to consider the final report at its meeting in December 2016.

The Tahoe Regional Planning Agency leads the cooperative effort to preserve, restore, and enhance the unique natural and human environment of the Lake Tahoe Region, while improving local communities, and people’s interactions with our irreplaceable environment. For additional information, contact Tom Lotshaw, Public Information Officer, at 775-589-5278.