The Lake in Winter
Studying Crater Lake presents unique challenges for scientists. Throughout the year, its secrets are guarded by extreme depths, approaching 2000 feet in some places. In the winter, surrounded by sheer cliffs covered with ice and snow, even getting to the lake is difficult and dangerous.

Scientists prepare to enter this world very carefully. “The logistics are fairly significant,” says Aquatic Biologist Scott Girdner. First, researchers must wait for a window of opportunity, when fair weather is likely to last through the duration of the trip. When (or if) it does, everyone must be ready to go on a moment’s notice. A helicopter is standing by, ready to carry people and supplies to the boathouse on Wizard Island. Of course, everything is buried by snow. In 1997 researchers spent a day and a half just digging out the boat house and a twelve foot wide path to the water for launching the research boat. Finally, scientists must be prepared to wait out a storm if the weather changes. They bring a month’s worth of food—and several decks of cards. If all goes well and the weather holds, they fly out within a week.

Why go to so much effort? Crater Lake has always sparked the imaginations of visitors, and scientists have recently begun to realize just how unique it really is. Crater Lake’s extraordinary depth, combined with a relatively small surface area and near-pristine water, make it similar to few other lakes in the world. It is a useful benchmark for scientists to compare with other lakes that are more intensively influenced by human activity.

Park scientists collect data on Crater Lake in January of 1988.

Scientists have explored many aspects of Crater Lake’s chemistry and ecology—but mostly during the three to four months the lake is accessible during the summer. Since 1986, researchers have visited the lake only six times in the months between January and April. As they do in the summer, scientists collect plant and animal samples, record water temperature and chemistry, measure nutrient levels and biological productivity, and monitor water clarity. These data are correlated with information gathered at weather stations on the rim and mounted on a buoy in the middle of the lake. In addition, a string of sensitive scientific instruments measures water temperature at nineteen different depths.

What we’ve learned so far is compelling. Water circulation in the winter brings nutrients to plants and animals near the surface of the lake. This mixing reaches deeper depths some winters than others, by a mechanism that is still poorly understood.

The resulting surge of nutrients may make biological activity most intense in the spring, before the lake is easily accessible and before most of our scientific research occurs. “What happens in the winter sets the stage for what we see in the summer,” says Aquatic Biologist Mark Buktenica. “We see the play without seeing the script.”

This motivates scientists to explore further, and to find creative ways of gathering information. Crater Lake’s ecology is too complex to understand with only intermittent visits. In the future, scientists hope to install more remote sensing equipment in the lake, in order to monitor conditions year-round.

Slowly, we are beginning to unravel the mysteries; but Crater Lake does not give up its secrets easily. At the dawn of the 21st century, it remains a place of mystery and wonder.

On the Lake in 1949
Crater Lake rarely freezes. Most years, heat stored in the water throughout the summer prevents ice from forming in the winter. The last winter Crater Lake froze over was in 1949, when ice completely covered the surface for more than two months.

On March 14, 1949, two park rangers walked across the ice to Wizard Island. Part way there, they found that the ice was only two inches thick, at a point where the lake was 1000 feet deep. They made a hasty advance to the island, then returned across narrow Skell Channel, where the ice was several feet thick.

Since 1949, Crater Lake has come close to freezing only twice: in January and December 1985, when more than 90% of the lake surface was covered with ice.