Five Things Ailing Lake Tahoe
1. Fine Sediment and Runoff
Hundreds of quintillions of ultra-fine particles find their way into the Lake in an average year–that’s billions of billions. About 70 percent of these clarity-damaging particles come from driveways, roadways and parking lots. Best Management Practices (BMPs) are required on all developed parcels in order to capture and infiltrate runoff before it gets into the roadway or the Lake. At the same time, state highway departments and local governments are investing hundreds of millions of dollars installing BMPs on roadways. Public agencies and some private property owners are restoring streams and marshes to help naturally filter fine sediment and other pollutants out of the stormwater.
2. Nitrogen and Phosphorus
More nitrogen is available today mostly because our cars and many older, inefficient wood-burning stoves spew it into the Tahoe Air Basin where it is often trapped over the Lake. More than 50 percent of the nitrogen going into the Lake comes from these local sources and falls into the water through atmospheric deposition where it feeds algae.
More phosphorus is available today mostly because of phosphorus-based fertilizers. The granitic soil of the Sierra Nevada already contains plenty of phosphorus for most plants and grasses, so any additional phosphorus is likely unused by plants and enters the watershed where algae use it to thrive. Phosphorus-free fertilizers are readily available and TRPA is phasing out the sale of phosphorus-based fertilizers in the Tahoe Basin.
3. The Great Building Boom and Its Legacy
The TRPA capped development in the 1980s, but a massive development boom through the 1950s and 1960s did damage to Lake Tahoe’s ecosystem that could take generations to repair. About 75 percent of Lake Tahoe’s marshes–essential to clean water and habitat–were filled in and 50 percent of meadows were built on. Additionally, buildings and roads were constructed without environmental design or sensitivity to wildlife and the soft, granitic soil of the Tahoe Basin. With an urban boundary firmly in place today and cutting-edge design requirements on all future projects, the challenge today is encouraging environmental redevelopment of these aging buildings and outdated infrastructure.
4. Cars and How People Get Around
Most development in the Tahoe Basin was planned and designed around the private automobile. Neighborhoods were built far from essential services like grocery stores and schools. Commercial centers were designed for convenient parking and less walking; and bicycling was not even an afterthought. As noted above, vehicle emissions have a significant effect on Lake Tahoe’s purity. They also harm air quality and visibility. Updating the design of our town centers and transportation corridors is essential to restoring Lake Tahoe and helping make our communities more walkable, bikeable and sustainable.
5. Imminent Threats