Tahoe World news Thursday, September 3, 1998 2:40 PM

The view from below:Tahoe's 'virtual library' offers dramatic images of the
lake's bottom

By Tanya Canino

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With the addition of the remarkable images from the recent mapping of Lake
Tahoe's bottom, visits on the Lake Tahoe Data Clearinghouse web site have
jumped dramatically.

Since it went on-line Jan. 16, Lake Tahoe's "virtual library" had about
3,000 visits in its first seven months of operation on the Internet. But
after the bathymetry of Lake Tahoe was put on the web site in mid-August,
the number of visits has risen to 12,000, according to Alexander Evans, the
site's webmaster and a physical scientist with the U.S. Geological Survey's
National Mapping Division in Menlo Park.

"That's actually generated a lot of interest," Evans said. "I watch the
hits and it's really climbed dramatically. The bathymetry has really
attracted a lot of attention."

Between Aug. 6 and 13, the USGS' coastal and marine geology group mapped
the floor of Lake Tahoe using acoustic sonar aboard the research vessel,
the Inland Surveyor.

The mapping revealed lake floor sediment patterns, sunken artifacts and
photograph-like maps of the bottom of Lake Tahoe.

"This is a key road map for future research and restoration," said
Secretary of Interior Bruce Babbitt in an on-line press release. "We need a
comprehensive understanding of all factors - particularly sedimentation
patterns and rates and the exact contours and water volume - so that we can
accurately predict what work will be most effective in restoring clarity to
the lake. These issues are very complex. But this project is an important
part of our fulfillment of the president's and vice-president's commitment
to protect this magical place, a place Twain called 'the fairest sight the
whole earth affords.'"

High resolution, 3-dimensional digital photographs are included on the Lake
Tahoe Data Clearinghouse site, showing the lake's depths in multi-colors
and pulling out different views of Lake Tahoe from under the water.

The dramatic images have attracted the general public to the web site,
located at http://blt.wr.usgs.gov/. Up to now, the site had mainly been
used by Lake Tahoe scientists, although people from throughout the world
visit the site.

The Lake Tahoe Data Clearinghouse is a "virtual library" of Lake Tahoe,
said John Nowlin, the district chief for the USFS Nevada division. It is
funded at $50,000 a year through the Presidential Deliverables, he said.

It provides data from the USGS and has links to other Tahoe-related
agencies such as the U.S. Forest Service, the National Resource
Conservation Service, the Tahoe Regional Planning Agency and the U.S.
Environmental Protection Agency, among others.

It was started because of the U.S. Presidential Forum in July 1997, when a
need was identified to create a clearinghouse of information for agencies'
use.

"I think the people pulling the data down and using it the most are
scientists," Evans said.

Many Tahoe agencies use Geographical Information Systems software to create
maps and data banks for their use. The Lake Tahoe Data Clearinghouse is
trying to post that information on the web site or link it to other web
sites so it can be used by all basin agencies, scientists and interested
people.

An example might be a map by the U.S. Forest Service of the basin's timber
management which the TRPA could use instead of creating its own map or by
overlaying new information on it such as stream zones. As the web master,
Evans tries to keep up on what different agencies are doing and help them
put their work on-line.

"It's trying to bridge a little bit for these different agencies. People
weren't talking about what they had. Now they do not have to re-create
something that has already been done," Evans said.

The coordination helps the agencies save time which results in a savings
for taxpayers, he said.

Evans says his favorite part of the web site is the e-mail he receives from
people using it - especially citizens.

He notes one man from Idaho who used the web site to download digital files
on elevation and topographical maps and then create a hiking map.

"We were in Tahoe July 25-29 and I brought my set of maps with us to use to
plan mountain biking trips," the man noted in a recent e-mail to Evans.

"It's fun to see a regular taxpayer using this stuff," Evans said.

He has received e-mail from scuba divers who agree that Lake Tahoe's
clarity has declined over the years, as well as an e-mail from a 36-year
resident who agreed with the push to improve Tahoe's clarity.

"They come from all over the world," he said, citing Internet visits from
Canada, Chile, Australia, Germany and Japan.

The Lake Tahoe Data Clearinghouse is an easy-to-follow site which provides
questions and help about downloading files, as well as information on the
various Tahoe agencies, the Presidential Forum and its status report on the
Presidential Deliverables.

There are aerial photos of Lake Tahoe, watershed maps, TRPA plan area
statement maps, land capability maps, topographical maps, water data,
scientific reports on various Tahoe subjects and even the day-to-day log of
the Inland Surveyor while it mapped the bottom of Lake Tahoe.

The maps and data can be downloaded from the web site by people with
Windows 95, Evans said.