Recent storms proved too much for fire-damaged areas near Angora
November 12, 2009
SOUTH LAKE TAHOE, Calif. – Alleged water quality violations at five U.S. Forest Service projects during an October storm that walloped the West Coast have caused the agency to take a look at how to better design projects to protect Lake Tahoe.
The Oct. 13 and 14 storm dropped more than 2.5 inches of rain at the South Shore in about 30 hours, according to National Weather Service observations.
The strength the of the storm caught the Forest Service off guard and left at least one South Shore project without adequate erosion control measures, said Forest Service spokesman Rex Norman on Tuesday.
The storm flushed excess nutrients and fine sediment into two Lake Tahoe tributaries: Tallac Creek and Angora Creek. The Lahontan Regional Water Quality Control Board has identified nutrients that promote algae growth and fine sediments as the primary causes of Lake Tahoe’s historical clarity decline.
Following the storm, the water board issued notices of violation to the Forest Service for alleged water quality violations at the Angora Hazard Tree Removal Project, Tallac Creek Bridge Project, Valhalla Pier Erosion Control and Accessibility Retrofit Project, Pope Beach Restroom Replacement Project and Fallen Leaf Lake Campground Best Management Practices Retrofit Project.
The water board contends each of the projects were not adequately winterized to prevent excess runoff by an Oct. 15 deadline.
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The Forest Service has disputed the water board’s allegations regarding four of the projects.
“In our examination of the (Best Management Practices) that were installed at Pope Beach Restroom, Fallen Leaf Campground and Valhalla Pier Projects, we have concluded that (Best Management Practices) were effective at preventing transport of sediment to water bodies and prevented adverse impacts to soil and water quality at the project sites,” wrote Terri Marceron, Lake Tahoe Basin Management Unit Forest Supervisor, in a response to the allegations.
The release of fine sediment into Tallac Creek at the Tallac Creek Bridge Project was caused by a stream diversion pipe that was unknowingly broken during construction and was not the result of inadequate erosion control measures, Marceron contends.
The water board found “minimal and incorrectly installed” erosion control measures contributed to the discharge of sediment-laden water into Tallac Creek, said Scott Ferguson, the chief of the water board’s Enforcement and Special Projects Unit, in a notice of violation dated Oct. 21.
The turbidity – or cloudiness – of Tallac Creek increased by 14,625 percent above background levels because of the discharge, Ferguson said.
The release has caused the Forest Service to look a how the project was designed, Marceron said.
“The methods used in the construction, design and placement of this diversion pipe followed accepted engineering practices, and this design has performed successfully on other projects,” Marceron said. “Nonetheless, we will be examining improvements to the design and implementation of the is precaution to reduce the risk of failure at future projects.”
Forest Service officials readily admit that erosion control measures at the Angora Tree Removal Project near Seneca Pond were not effective during the storm. The project’s goal is to remove trees damaged by the Angora fire that had the potential to fall on roads and trails in the popular recreation area.
Pictures of the project during the storm show muddy rivulets cutting through access roads and depositing murky water into Angora Creek tributaries.
“These (Best Management Practice) implementation failures resulted in effectiveness failures, which in the end resulted in an unacceptable discharge of runoff and pollutants into a tributary of Angora Creek,” Marceron said.
The Forest Service has since ensured adequate erosion control measures are in place at each of the projects to prevent a repeat in the event of another storm, Marceron said.
In addition the Forest Service has begun to “identify the causes of these implementation failures, as well as solutions to incorporate in future (National Environmental Policy Act) documents, contracts and monitoring processes to reduce the risk of implementation failure in future projects,” according to Marceron.
“In the long term, we would like to schedule a post storm debriefing to discuss (Best Management Practice) implementation and effectiveness successes and failures, including lessons learned to improve future success,” Marceron said.
Whether or not the Forest Service will face fines from the alleged violations is unknown, although the initial indication from the water board is that the agency will not, said U.S. Forest Service forester Duncan Leao.