CMG Maps Bottom of Crater Lake, Oregon

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CMG Maps Bottom of Crater Lake, Oregon

By Helen Gibbons
September 2000

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Bottom of Crater Lake: Oblique view of shaded-relief bathymetry of Crater Lake, Oregon, looking north. Colored region is the new shaded-relief bathymetry of the lake floor. Gray region is shaded relief of surrounding land generated from a USGS 10-m digital elevation model (DEM). Distance across the lake is approximately 9.5 km. Vertical exaggeration 2X.

A mapping mission that was nearly scrubbed because of wildfires in the West met with spectacular success last month.

Jim Gardner, Pete Dartnell, and post-doc Laurent Hellequin (MPFC) completed a high-resolution multibeam map of the bathymetry of Crater Lake, in Crater Lake National Park, Ore, in early August. They worked with Larry Mayer of the University of New Hampshire, four contractors from C&C Technologies, Inc., of Lafayette, La, and two rangers from Crater Lake National Park. The plan to map the lake bottom was initiated last year by Mac Brock of the National Park Service, which partnered with the USGS to fund the mapping.

Logistics were complicated by the fact that the lake surface lies about 1,000 ft below the crater rim and is accessible only from the air or by a mile-long foot trail. So C&C Technologies' 26-ft research boat, R/V Surf Surveyor, had to be airlifted onto the lake.

R/V Surf Surveyor
R/V Surf Surveyor: R/V Surf Surveyor on its transport cradle. The boat was built especially for this project by C&C Technologies in Louisiana and trucked to Crater Lake. The multibeam acoustic transducer is the red object mounted just forward of the keel.

An element of suspense was introduced when the commercial helicopter scheduled to do the airlift was diverted to fight wildfires. In fact, all the commercial helicopters in the area were called upon to fight fires, and for a few days it was not clear whether the mapping, which was supposed to begin on July 24th, would proceed at all.

Finally, on the 28th, the U.S. Army Reserves came to the rescue with a Chinook helicopter from Fort Lewis, Wash. The helicopter airlifted the Surf Surveyor onto the lake, the mapping crew set up their processing center on Wizard Island, and mapping began.

The mapping delay and assistance from the Army increased media interest in the project, which received a lot of local newspaper and TV coverage. Once the project was underway, the mapping crew worked quickly, processing each day's data on the island field camp for daily posting on the World Wide Web. Mapping was completed in five days, and a final bathymetric map was shown to the media at a press conference held at park headquarters on August 3rd. The new map is accurate to within 50-cm depth and resolves objects larger than a few meters in diameter. It shows a maximum lake depth of 1,958 ft, 26 ft deeper than previously measured, and reveals never-before-seen details of ancient lava flows, huge landslide debris fields, and other geologic features on the bottom.

helicopter over Crater Lake
Airlift: U.S. Army Reserves Chinook CH-47D helicopter from Fort Lewis, Washington, airlifts C&C Technologies' R/V Surf Surveyor onto Crater Lake. field station on Wizard Island
Field Station: The mapping crew's field station and processing center on Wizard Island. The primitive living conditions were ameliorated by the successful mapping and by the culinary skills of a Cajun cook from C&C Technologies.

You can see bathymetric images and fieldwork photos at the "Crater Lake Data Clearinghouse", a Web site created and maintained by Alexander Evans, Connie Hoong, and Gary Sullivan of the National Mapping Division in Menlo Park. The Web site was developed and added to by:

CMG researchers, who processed the previous day's data while C&C contractors were on the lake collecting more data;

park rangers, who made daily treks up the foot trail with computer disks containing the processed data; and

park computer specialists, who transferred the processed data from the park headquarters to Menlo Park.

Also on the Web site is a wealth of information about the Crater Lake area and its natural and human history.

Crater Lake Data Clearinghouse
U.S. Geological Survey (USGS)

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September 2000

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in this issue: cover story:
Recovery of Confederate Submarine H.L. Hunley

Crater Lake Mapping

Lake Erie Nearshore Habitat

Channel Islands

Pinnacles Area—Gulf of Mexico

Gulf of Maine

Seafloor Mapping Seminar

Ocean Science Forums

Blacks in Government

SF Bay Oil-Spill Hazards

Gas Hydrates

Presentations

Arrivals

Visitors

September Publications List