Photos: A water-filled crater

Scientists study Crater Lake with aquatic robots and highly sensitive sonar to unlock the mysteries of one of the world's most pristine lakes.
By Andy Smith, Contributor
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Lake view

Crater Lake, in southern Oregon and about a two-hour drive from the California border, formed nearly 7,700 years ago when the volcano, Mount Mazama, violently erupted. The volcano collapsed on itself with enough force to incinerate parts of Oregon, Washington and spewed ash as far as Vancouver and Kansas. The event exerted 46 times more force than that of San Francisco's 1906 earthquake.

Scientists believe the hole left after the explosion filled up with snowmelt and rainwater over the next 600 to 800 years to form Crater Lake. Because the volcanic terrain limits the amount of nutrients in the lake and bars streams from coming in or out of the lake, the water is pure blue and largely comprised of snowmelt.

The lake is a U.S. National Park.

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Family at lake

A family enjoys Crater Lake, after climbing down the only trail that leads 1,000 feet down to the edge of the water. The water's temperature is typically about 68 degrees in summer, but can heat up to 74 degrees on hot days. It's as cool as 38 degrees near the bottom of the lake, but pockets of water at 68 degrees suggest hydrothermal activity, meaning the volcano is still active.

The last time the lake froze over was in 1949.

About a half a million tourists visit Crater Lake every year and the most common question among them is, "Are there fish in the lake?" Yes, according to park rangers.

William Gladstone Steel, an explorer who helped establish the lake as a national park, carried buckets of minnows into the lake after his first visit in 1885.

Only two species of fish--kokanee salmon and rainbow trout--out of more than 40 introduced to the lake have survived, however, and the populations are sparse. The public is allowed to fish in the lake without a license.

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Clear water

Crater Lake is one of the clearest freshwater lakes in the world because it contains very few nutrients and particles. Divers can typically see nearly 150 feet away, but the lake's elevation limits how far scuba divers can venture to about 100 feet. Light stops in the lake at about 600 feet.

The lake is as about six miles wide. And its water typically stays at a constant level, given the annual snowmelt and rainfall is roughly equal to the lake's evaporation and seepage.

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White bark pine

A white bark pine tree at Crater Lake's Sinnott Memorial Overlook suffers from disease. A park ranger with the National Park Service said that the tree's health, like others in the area, threatens the existence of the Clark's Nutcracker, one of the most common birds at Crater Lake. The Nutcracker extracts and then re-plants seeds in the tree for nourishment, and as this tree shows, mealtime is over.

Another common species of Crater Lake is the olden-mantled ground squirrel, a tiny brown animal that can be spotted foraging all over the park.

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Robert Collier

Robert Collier, an associate professor of oceanographic biology at Oregon State University, hosts a scientific talk on Tuesday about his aquatic moss studies. Here, he points to live video transmitted via satellite from a boat on Crater Lake, which is collecting video and data from a submersible robot in the Danger Bay area of the lake.

Collier and others are collecting samples of moss beds in the lake in order to study its age and the overall ecosystem of Crater Lake.

In the future, Collier hopes to be able to conduct field studies and watch biological changes in the lake from fiber-optic cable hooked up to video cameras and sensors installed in the water. "But it will be hard to get cables down there," he said.

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Wizard Island

A view of Crater Lake from the ridge of Mount Mazama. The rim of the lake is 33 curvy miles to the highest peak of nearly 9,000 feet. Wizard Island sits at the center of Crater Lake.

Scientific experiments have been conducted on Crater Lake for the last 100 years. But in 1994, the National Park Service established a program to continuously monitor the park indefinitely. The lake is pristine, except for the introduced fish species.

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Lake model

A model of Crater Lake at the Sinnott Memorial Overlook gives visitors a broader prospective of the lake's clarity, depth and structure.

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Crater Lake Lodge

Unlike Lake Tahoe, which at a depth of 1,700 feet rivals that of Crater Lake's 1,932 feet, the park is largely unpopulated and un-commercialized. The lone lodge at the rim, called the Crater Lake Lodge, is nearly 100 years old and has only 71 rooms. The historic lodge was redone 10 years ago, so it's now as pristine as the lake, but prospective tourists often have to reserve a room years in advance, or camp down the mountain.

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Exposed rocks

Another view of Crater Lake and Wizard Island, with rocks as old as 420,000 years exposed. Scientists have estimated that rocks on the southeast edges of Wizard Island are as young as 5,100 years old.

"We're talking about hundreds of thousands of years of geology exposed," Collier said.

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An engineer on the research boat controls the remotely operated vehicle, or ROV, at a depth of 450 feet in the Danger Bay area of Crater Lake. He can watch the robot and its surroundings from a video signal transmitted to the PC-to-television hookup.

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High-def robot

The robot is equipped with two high-definition digital cameras--one that takes color video and another for black and white--and with GPS for navigation.

Sonar on the top of the robot also collects data on the biomass of the moss, blue-green algae and other life in the lake.

The robot has seven thrusters--four mechanisms to go forward and back, two to go side to side, and one to spin. It is also neutrally buoyant, meaning that it doesn't sink or float. It's controlled by a so-called altimeter, which measures depth and can be set to stay a certain distance from the lake floor or caldera wall.

Two engineers on a boat control the robot's movements. Data and video from the robot is transmitted via wire to a computer on the deck of the boat. The PC takes in and transmits signals from the altimeter.

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Moss tree

A tree covered in moss on the only trail leading to the lake. The walk down is a cinch compared with the climb up, which can be compared to walking 150 flights of stairs to the 75th floor of a building.

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