History of LADWP Snow Surveys
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Mammoth Mountain Ski Area President Dave McCoy (right, with an unidentified co-worker) started as a LADWP Hydrographer in the 1930's. |
Snow surveying, or the measuring snow depths to determine spring and summer water runoff, began in California’s Sierra Nevada mountain range in 1906 with the work of Dr. James Church of the University of Nevada at Reno. Dr. Church began measuring snow on Mount Rose, just east of Lake Tahoe, to study the relationship between the amount of snow on the ground and runoff.
In 1910 the first permanent snow courses as we now know them were set up and measured in the Tahoe Basin. Hydrographers placed markers on the ground at specific locations and returned on a regular basis to measure the amount of snow at the site, and the water content in the snow.
Dr. Church's measurements helped put an end to battles between land owners surrounding Lake Tahoe and downstream water uses by predicting spring runoff so that water releases could be regulated to prevent both flooding and the waste of water. His pioneering work in snow hydrology continues to be the foundation for water supply forecasting today.
Hydrographers from the Los Angeles Department of Water and Power visited Dr. Church in 1925 to learn his techniques. Taking what they had learned, DWP crews established snow courses and began regular snow surveys 1926 at four Eastern Sierra basins: Cottonwood Canyon, Big Pine Canyon, Rock Creek and Mammoth Pass. Today, these four locations continue to provide valuable data used by DWP runoff forecasters.
In 1929 the California State Legislature, after
seeking input from the major water providers in the state, enacted legislation that formed
the California Cooperative Snow Survey Program. This
established a coordinated and centralized snow survey program to provide information for
water users across the state. By 1929 there were already 50 snow courses around the state
being measured on a regular basis. Most of these courses were located in the Eastern
Sierra and provided data for flow into Lake Tahoe and the Mono Lake and Owens River
Basins. The CCSSP now has 40 members and measures more than 280 courses throughout
California.
In the the early years of snow surveying, hydrographers traveled to survey sites using a variety of methods including snowshoes, nine-foot wooden skis and even dogsled teams. More recent times have seen travel by snow-cats, snowmobiles, and even helicopters. However, hydrographers continue to rely on snowshoes and skis to get the job done. And the main part of the work still involves long days in conditions that vary from intense snowstorms to hot sunshine and can even mean spending a night out in the backcountry.
Beginning in 1971 and continuing to the late
80's, the DWP, in cooperation with the State of California, began developing a system to
collect snow data from the backcountry without people having to visit far-off sites. Over
the years a number of telemetry sites have been installed that now provide data that is
updated automatically several times a day and relayed it to a central information
collection location.
Mattress-sized "pillows" filled with an antifreeze-type liquid have been installed at snow survey sites. The weight of snow falling on the pillows displaces the liquid in the pillows, producing a data signal that is transmitted to the California Department of Water Resources in Sacramento via telephone line, radio or even satellite. Data collected includes water content of the snowpack, temperature, wind and solar radiation. While the data is only considered preliminary until it is verified by hydrographers doing a snow survey, it is accessible over the Internet.
Although this system is still in the development stages, it provides valuable data used to determine trends in the snowpack. Tests are currently being conducted throughout the west with the hope of finding a more reliable instrument for monitoring water content in the snowpack. Until that time the backbone of the snow survey program remains the "snow surveyor" who measures the snow by hand, just like it was done almost 100 years ago.