California and Nevada researchers are planning the most exhaustive study to date of the geologic history of the Lake Tahoe Basin. The results should help public agencies keep the lake blue and the groundwater clean, and assess the threat of landslides, earthquakes and tsunamis.

"Government and university scientists have learned a lot about the basin in three dimensions," said UC Davis geology professor Ken Verosub, who leads the project's scientific organizing committee. "Now we need to add the fourth dimension, that of time, to truly understand the present and the future."

Verosub said the most modern approaches will be used to reconstruct the tectonic and climate forces that shaped the region over the past 2 million years. Researchers will collect information through direct observations on the ground; by taking cores of sediment from the land and from the bottom of the lake; and by studying how sound waves are transmitted through the ground and the water.

In addition to benefiting the Tahoe region, the study is likely to produce knowledge that will be useful to scientists trying to reconstruct the climate history of North America. The sediments of the Tahoe Basin are thought to contain a continuous two-million-year record of climate, one of the longest on the continent. The researchers will "read" this record by studying clues such as fossil pollen, sediment grain size, and oxygen and carbon isotopes.

Verosub said if research were to begin by the fall of 2006, local agencies could have useful information in hand by the summer of 2007. The yet-unnamed project has start-up funding of $28,000 from Drilling, Observation and Sampling of the Earth's Continental Crust (DOSECC), an NSF-funded consortium of 52 universities that fosters scientific coring studies and develops the technology to support them.

The entire project could cost $2 million to $5 million. The researchers will solicit support from the National Science Foundation, the U.S. Environmental Protection Agency, the U.S. Geological Survey (USGS) and others.

The core samples will be collected using boats on the lake and truck-mounted coring machines on land. The scientists hope to end up with at least 50 cores, ranging from 30 feet long to almost 1,500 feet long. (If the sections of a 1,500-foot core were stacked vertically, they would be about 5 times as tall as the 18-story Harrah's Lake Tahoe casino and hotel on the south shore.)

The cores will be used to answer fundamental scientific questions about the basin's historic climate, or paleoclimate; the role of earthquakes, landslides and volcanic activity in shaping the basin; the history of glaciation; and the subsurface movement of water. Verosub said the answers to these questions should give planners and policymakers a firmer basis on which to make decisions about restoration and preservation of Tahoe's environment, about dealing with the threats to Tahoe's inhabitants and structures from geologic hazards, and about control and remediation of groundwater contamination.

The research project is currently in the early design stage, with a September workshop planned at Lake Tahoe for about 60 scientists to begin working out details and timelines. Workshop invitations went out to scientists this week. Verosub said there will be opportunities for public input and comment as the project progresses.

The coring activities in the Lake Tahoe region will be conducted according to strict environmental protocols, Verosub said. "DOSECC is a leader in the development of coring methods that have little or no environmental impact and they have successfully cored in a variety of sensitive environments around the world."

Verosub has worked on many coring projects around the world, from Antarctica to China. In his laboratory at UC Davis, he has analyzed the magnetic properties of more than 10 miles of core in the past 10 years.

The other scientists on the organizing committee are Geoff Schladow, director of UC Davis' Tahoe Environmental Research Center (formerly the Tahoe Research Group); Dave Osleger and Irina Delusina of UC Davis; Rich Schweickert of the University of Nevada, Reno; Ken Adams of Desert Research Institute in Nevada; Graham Kent of Scripps Institute of Oceanography at UC San Diego; Gordon Seitz of San Diego State University; and Scott Starratt, André Sarna-Wojcicki and Vic Mossotti of the USGS in Menlo Park, Calif.

Additional support for the workshop is coming from the John Muir Institute for the Environment at UC Davis, the Tahoe Environmental Research Center, the Desert Research Institute, the Academy for the Environment at UNR, the Institute for Geophysics and Planetary Physics at UC San Diego, and the USGS.

Many academic institutions and public agencies are working together to restore and preserve the Tahoe Basin ecosystem. Some of the most active research programs are at UC Davis, UNR, the Desert Research Institute, NASA, the California Regional Water Quality Control Board, the Nevada Division of Environmental Protection, the California Air Resources Board, the U.S. Forest Service and the Tahoe Regional Planning Agency.

All are currently engaged in producing an unprecedented set of environmental management plans for the basin, called Pathway 2007.

To further understand the lake, UC Davis' John Muir Institute of the Environment has established the Tahoe Environmental Research Center, a $13 million research and education center, which will be housed in a new science building now under construction on the campus of Sierra Nevada College in Incline Village, Nev.