Crater Lake NP in Winter, November 2009 Dave Harrison West Rim ski trail

Frequently Asked Questions

Frequently Asked Questions about Crater Lake

We asked a few of our members (many were naturalist rangers at Crater Lake) what were some of the most common questions asked by crater lake visitors.

Why is Crater Lake so blue?

The water is so blue because there is hardly anything else in it – just water. It’s not pure water, but it’s close. Water molecules with no sediments, algae, pesticides or pollution, will absorb all the colors of the spectrum except the blues. Those wavelengths will bounce back and make the water appear blue. The key is to have relatively pure water and lots of it. There has to be enough molecules to absorb all the other colors. (There are 4.6 trillion gallons of water in the lake, so it works really well.)

Does the crater lake ever freeze over?

Although snow occupies Crater Lake National Park throughout 8 months of the year (average annual snowfall is 14 m, or 533 in), the lake rarely freezes over. There have been only two reports of this ever happening. It was completely covered by ice from March 14 to mid May during the winter 1949 and four days in February, 1924. In April, 1983 about 95 percent of the lake froze. The immense depth of Crater Lake acts as a heat reservoir that absorbs and traps sunlight, maintaining the lake temperature at an average of 12.8 °C (55 °F) on the surface and 3.3 °C (38 °F) at the bottom throughout the year. The surface temperature fluctuates a bit, but the bottom temperature remains quite constant.

How far is it around Crater Lake?
33 miles.

Are there eagles at Crater Lake?

Bald Eagles are fairly common at Crater Lake during summer, but much larger numbers can be seen at the nearby Upper Klamath Lake National Wildlife Refuge. The winter eagle population may reach one thousand migrant birds.

How far down to the water?

The rim rises anywhere from 500′ to almost 2,000′ above the lake’s surface, creating a spectacular visual effect. The distance from the rim village area (the area of the Crater Lake Lodge) to the surface of the lake is approximately 900 feet.

How was Crater Lake formed?

The phrase “GREW, BLEW, FELL, and FILL” describes the process that created Crater Lake.

Grew – Mount Mazama was a large composite volcano that was built during the past 400,000 years by hundreds of smaller eruptions of lava flows. Mount Mazama rose to an approximate height of 3,700 m (12,000 ft) above sea level.

BLEW – About 7,700 years ago, Mount Mazama erupted catastrophically, blowing out about 50 km3 (12 mi3) of magma in a few days. The volcanic ash covered parts of the northwestern states, spreading as far as central Canada. Rare particles of Mazama ash have even been found in ancient ice from Greenland. The airfall pumice and ash covered a total surface area of more than 2,600,000 km2 (1,000,000 mi2) at least 1 mm thick. A volume of 42-54 km3 (10-13 mi3) of the mountaintop had disappeared. Where had all this mass gone? Did Mount Mazama blow its top off?

FELL – Mount Mazama did not blow its top off; it collapsed in on itself. As this enormous volume of magma was rapidly removed from the chamber to feed the climactic eruption, it created a huge void underneath the mountain. Leaving no support for this massive dome, the roof of the magma chamber collapsed, forming the bowl-shape depression known as a caldera.FILL – About 5,000 to 6,000 years ago, the accumulation of rain and snow filled the caldera. It took perhaps 250 years for the caldera to fill to its present-day lake level, which is maintained by a balance between precipitation and evaporation plus seepage.

How deep is Crater Lake?

Crater Lake is known to be the deepest lake in the United States and the seventh deepest in the world. The maximum lake depth of 589 m (1,932 ft) was established in 1959 by the USGS using sonar measurement. But since its primary input source is dependent upon the climate, lake level is subject to abrupt changes. The caldera is a bowl-shape depression of about 1,219 m (4,000 ft) deep.The maximum depth of Crater Lake recorded at the time of the July 2000 multi-beam survey was 594 m (1,949 ft). The lake level had an elevation of 1,883 m (6,178 ft) above sea level at the time of the survey.

What is the distance across Crater Lake?

Approximately 9 kilometers (5.6 miles). It’s maximum width is approximately 6.02 miles and it’s minimum width is approximately 4.54 miles.

When was Crater Lake established as a National Park?

Crater Lake: the 5th, 6th, or 7th park established? It depends on how you look at it. If you only consider existing national parks, Crater Lake could be numbered as high as the fifth national park. Crater Lake became #5 with the decommissioning of Mackinac Island and the absorption of General Grant into the current Kings Canyon National Park. If you allow General Grant to remain, we are #6 on the list. If you stick to the original list, regardless of present status, Crater Lake was the seventh national park to be established.

How much snow does Crater Lake get?

The average snowfall at Crater Lake is 533 inches every year. That’s about 45 feet. The greatest cumulative snowfall for one season was 879 inches (73 feet) the winter of 1932-33. The greatest depth on the ground at one time was 258 inches (21½ feet) the winter of 1983. Most of the snow usually melts by the beginning of August, although after particularly heavy seasons, there are drifts that fail to melt before the snows return again in the early Fall.

Why does Crater Lake get so much snow?

The major weather patterns at Crater Lake National Park originate in the Pacific Ocean. Storm events originate in the north Pacific and build in strength and moisture content over the ocean. Wind patterns at these northerly latitudes move storms from the ocean to the Pacific Northwest.

Over 100 inches (250 cm) of rain falls each year on the Oregon Coast. After crossing the Coast Range, storm clouds descend into the Rogue and Willamette Valleys, dropping about 30 inches (76 cm) of rain. As storms move eastward, the high mountains of the Cascade Range push the cool, moist air to elevations over 10,000 feet (3,000 meters) in many places. As the air rises, it cools further. Water vapor in the air condenses to form clouds, and snow crystals form within them. If there is enough moisture in the clouds, the snow begins to fall. If the temperature is warm enough, the snow melts before it reaches the ground and falls as rain.

Are there any fish in the lake? Where can I go fishing?

There is no way to know for sure fish are not native to the lake because the first visitors stocked Crater Lake. They were introduced in the lake from 1888-1941. Six species were originally stocked, but only two have survived to today: Rainbow Trout and Kokanee Salmon. Because they are not native to the lake, fishing is not only allowed, it’s encouraged. No license is required and there is no limit on how many you may catch – the only rule is that you must use artificial bait. We don’t want to accidentally introduce any other species into the lake. Fishing is allowed along the shoreline and on Wizard Island (with the purchase of a boat tour and Wizard Island ticket.)

What kind of birds might I see?

Most common birds seen in the park: Raven, Clark’s Nutcracker, Gray Jay, Steller’s Jay, Dark-Eyed Junco, and Mountain Chickadee.
How cold is the water of Crater Lake? The average temperature (below 300 feet deep) is 38°. In the summer, the surface can warm up to 55° or 56°.

Where can I get to the lake to go swimming?

There is only one place where it is safe and legal to get down to the lake edge. It is the Cleetwood Cove Trail, which usually opens mid to late June. Visitors are welcome to swim in the lake from the shoreline at the end of this trail.

What kind of animals are at the park?

The most common are Roosevelt Elk, Mule Deer, Black Bear, Coyote, Bobcat, Porcupine, Yellow-bellied Marmot, Pine Marten, Snowshoe Hare, Pika, Golden-mantled Ground Squirrel, and Townsend Chipmunk.

What is the yellow stuff floating in Crater Lake?

Through the month of June and into July, yellow swirls of “stuff” can be seen on the surface of the lake and will always prompt great concern from the visitors. It’s not pollution or oil or some sort of chemical foamy stuff, it’s merely pine pollen. It’s harmless to the lake and will eventually settle out to the bottom.

Was there a volcano here?

Yes, and there still is! For approximately 400,000 years, volcanic eruptions here built up a 10,000 – 12,000 foot mountain now called Mt. Mazama. Seven thousand seven hundred years ago, the volcano exploded in a cataclysmic eruption. During this eruption, so much material was evacuated from the internal magma chamber that afterwards, there was not enough left to support the remaining mountain and it collapsed and created the hole – the caldera – that we now see today half filled with water.

Did they find the meteor that made Crater Lake?

This is not a meteor crater – a hole made by the impact of a big rock from space – so there is no meteor to find. Rather, this is a volcanic caldera – a hole made by the collapse of a volcano.