A restoration project of the Truckee River, designed to improve the clarity of Lake Tahoe, will result in the construction of an approximately 4,000-foot-long winding river channel this summer to replace the relatively straight channel that exists today.
A three-year, nearly $8 million restoration of a city-owned section of the Upper Truckee River - in an area east of the Lake Tahoe Airport - will undo some of the historic damage to the river, including harm done when the river was diverted to a new channel as part of a runway expansion in 1968.
"The deeper, wider and straighter channel has a greater capacity to transport sediment and provides poor aquatic habitat," according to a project description from the California Tahoe Conservancy, which is providing most of the funding for the project.
The Upper Truckee is the largest tributary to Lake Tahoe and is identified by the Lahontan Regional Water Quality Control Board as a major source of fine sediment that can cloud Tahoe's clarity.
About 43,000 cubic yards of fill also will be excavated to construct a 17-acre floodplain along the new channel of the river.
The Upper Truckee currently overflows its banks about once every three to five years, but with the new, lower floodplain, the river should overflow its banks every one-and-half to three years, said Jennifer Quickel, an assistant engineer with the city. The more frequent overflow will allow the floodplain to absorb more sediments and nutrients before they reach Lake Tahoe, Quickel said.
But the project is about more than water quality, said Conservancy program analyst Scott Carroll.
Fish habitat structures, the removal of barriers to fish movement and use of vegetation meeting habitat needs of species such as the willow flycatcher make the project a full "ecosystem restoration" rather than purely a water-quality project, Carroll said.
Several challenges face the project, including maintaining compliance with Federal Aviation Administration rules, protecting a South Tahoe Public Utility District sewer pipe near the river and undertaking an extensive project in a relatively small area bordered by an airport, Carroll told representatives from the project's more than a dozen partner agencies Thursday.
Moving such a large amount of soil near an active river channel also raises the concern of sediment from construction getting into the river and degrading water quality.
Depending on the effectiveness of replanting efforts in 2009, the river could be diverted into the new channel by 2010 or 2011.
Construction on the restoration project likely will occur between July and September during each of the next three or four summers, Quickel said.