Home A - Z FAQ Art Prints Online Library Discussion Forum Muir Weather Maps About Search
Online Library: Title Author California Geology History Indians Muir Mountaineering Nature Management

Next: Flood of 1977ContentsPrevious: Hiking

Yosemite Nature Notes 47(3) (1978)


THE EFFECTS OF THE DROUGHT ON YOSEMITE NATIONAL PARK

Lauren Tissol

“Valley Visitor Center. May I help you?”

The voice at the other end replied, “Yes. I am calling from Chicago and I am planning to visit Yosemite Park next month. I know California is having a drought and I was wondering if it would be worth my while to visit Yosemite. Is it all dried up and brown?”

I looked out the window at the oaks coming into bloom and the green meadows beyond. He was correct in assuming that if California was having a drought Yosemite would be affected. But most people forget that Yosemite encompasses a great land area, and elevations that range from 2,500 foot foothills to mountain peaks of 13,000 feet. Within its boundaries, each area has a different network of lakes and rivers and a precipitation pattern common to that elevation and terrain. Some areas of the park were severely affected by the dry weather and others very little.

The effects of the past year and a half of drought were reflected in the snow surveys. Each winter, the snow depth and the water content are recorded at eleven snow courses in Yosemite. The Gin Flat snow course, located on Highway 120 just northeast of Crane Flat, is typical of the results gathered at other locations.

GIN FLAT SNOW COURSE
7,000’ elevation
SNOW DEPTH (INCHES)
MONTH19771976AVERAGE   % OF AVERAGE
1977
MayBare14.478.90%
April17.522.778.222%
March15.929.874.321%
January15.30.059.625%

In the winter of 1976-77 at Gin Flat, there was 17% of the average snowfall. This lack of precipitation for the second successive winter necessitated that a Drought Action Plan be formulated. The Drought Plan set up guidelines for what should be done to preserve the natural objects within the park and to provide domestic water. The three phases of this plan required increasingly stringent steps to be taken to conserve water. The Yosemite Park and Curry Company, the main concessioner, also set up water conservation guidelines for its facilities and employees. The park visitor was asked to minimize water use. As the months passed and water became more scarce, areas in the park moved from each current phase of the Drought Action Plan to the next more restrictive phase.

By the beginning of August, the waterways in Yosemite Valley had diminished drastically. Summers in Yosemite are normally dry, but 1976 and 1977 were drier than normal. Tenaya Creek dried completely and Mirror Lake, fed by the creek, was a moist mudflat. The Merced River, a major waterway that passes through Yosemite Valley from one end to the other, continued to flow but at a level that hadn’t been observed in many decades.

A decrease in flow in a river will allow dissolved solids to increase in concentration and may also affect the temperature of the water, thus affecting the aquatic plants and animals. The Resources Management Division kept an eye on all the waterways in the Park and whenever possible, reduced the human use of water so that more would be available for the plants and animals. When Bridalveil Creek became very low in July, restrooms and water taps in Bridalveil Creek Campground were shut off and it was made available only to self-contained vehicles. In the latter part of the summer, campgrounds on the western end of Tioga Road had no water, and visitors were asked to bring their own water.

Many people were concerned with the fire danger present during a drought year. Some areas in the Sierra Nevada and the coastal mountains of California experienced fires of great magnitude, but Yosemite fared well. For two days in July, Yosemite Valley was filled with smoke so dense that one could barely see from one Valley wall to the other. It was said that this smoke had blown from the Mt. Diablo fire, located in the coastal mountains some 200 miles to the west.

Backpackers in Yosemite carried a lot more water in 1977 than they had in many years. Only lakes and major rivers could be counted upon to have water when the thirsty backpacker reached his destination. The Backcountry Division asked that all water be purified and stressed the importance of not introducing anything foreign into the waterways. In many areas, there simply wasn’t enough water available to dilute the concentration of unnatural pollutants to a tolerable level for consumption by living things.

Some areas of Yosemite were greatly affected by the drought and others very little. If the dry winters continue, more of the Park will be affected and animal and plant distribution and migration may alter significantly. Changes brought about by a drought or other natural phenomena are normal to a natural area like a national park, and Yosemite continues to change every day.



Next: Flood of 1977ContentsPrevious: Hiking

Home A - Z FAQ Art Prints Online Library Discussion Forum Muir Weather Maps About Search
Online Library: Title Author California Geology History Indians Muir Mountaineering Nature Management

http://www.yosemite.ca.us/library/yosemite_nature_notes/47/3/drought.html