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Drought and the 1992 Pond Survey

Introduction

The summer of 1992 arrived with a combination of circumstances that may earmark this season as having the most extreme drought conditions ever recorded in the history of Crater Lake National Park. Two factors were instrumental in making this happen. First, Crater Lake National Park experienced a very dry winter and spring from December 1991 to May 1992, with snowfall for that period being 45 percent of the average amount. This has a historic significance because it marks the lowest accumulations of snowfall in the 60 year weather record of Crater Lake National Park. Second, the summer of 1992 marks the sixth consecutive year of drought in this region, though below average precipitation has been the rule for all but three years in the past fifteen. Inasmuch as the park’s surface water resources were already under stress, the record low snowfall of this winter and spring intensified the scenario.

Six Ponds That Survived the Drought

Twenty eight ponds are located inside the boundaries of Crater Lake National Park, with most situated in the western half of the park. The majority of these ponds have depths of two to four feet when filled with water and have maximum diameters ranging from 30 to 200 feet. Spruce Lake is the largest of the ponds, with a maximum depth of about 12 feet end a length of over 300 feet. Several ponds in the Sphagnum Bog area and on Whitehorse Bluff have maximum depths of six to eight inches and diameters of 20 to 50 feet. All of the ponds appear to be filled only by direct rain or snowfall rather than by surface water. Some subsurface inflow is a possibility in a couple of ponds. The ability of these ponds to sustain appreciable water levels through the dry summer seems to be governed by the substrate that forms the basins where these ponds are located. Ponds which are poised in depressions on the surface of lava flows, like Quillwort Pond and Whitehorse Pond #3, for example, are the most persistent, whereas ponds poised in pumice fields from Mount Mazama’s climactic eruption, like Spruce Lake and Lake West, are the least persistent.

During the summer of 1992, it is likely that only six of the twenty eight ponds in Crater Lake National Park did not dry up before the first substantial storms came in mid October. These ponds are listed in the table and can be found on the I :62,500 topographic map of the park published by the U. S. Geological Survey. The figures delineate the locations of ponds in the Sphagnum Bog and Whitehorse Bluff areas.

Most persistent ponds of Crater Lake National Park. (see maps for the numbering system used with ponds in the Sphagnum Bog area and on the Whitehorse Bluff.)

Sphagnum Bog ponds

Whitehorse Bluff ponds

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