CW3E Embedded Hydrologist Joins CA DWR for Castle Creek Snow Survey

May 15, 2025

(L-R) Lauren, Andy, and Gabe approach the Castle Creek snow course on backcountry skis. (P.C. Nick Shockey, DWR).

On April 30, 2025, CW3E hydrologist Gabe Lewis joined DWR Snow Surveys and Water Supply Forecasting Unit engineer Lauren Alkire, manager Andy Reising, and DWR photographer Nick Shockey, for the final snow survey of the year at Castle Creek, located near Donner Pass, CA. They donned backcountry skis with skins to access the start of the snow course, located 1.5 miles from the trailhead.

Manual snow measurements are quite physically demanding, requiring the surveyors to plunge a metal tube through the snowpack to collect a sample before weighing it on a calibrated scale. During the springtime, these measurements become even more difficult because the snowpack densifies, meaning that the snow tube must be strongly thrust downward to penetrate through the refrozen ice layers. Taking turns and helping each other during difficult samples, Lauren, Andy, and Gabe were able to successfully measure all 10 points along the snow course, at the same exact locations that DWR has been measuring this course since 1946.

Gabe and Lauren weigh the snow tube to collect a snow water equivalent measurement. (P.C. Nick Shockey, DWR).

The team measured an average snow depth of 85”, with a water content of 41”, representing 98.5% of the 1991-2020 average. These measurements come after a relatively “average” winter in northern California, with a nearby meteorological station at the Central Sierra Snow Laboratory recording 57” of precipitation, 101% of the climatical average. The snow course measurements help DWR’s team forecast the April-July Yuba, American, and Truckee River runoffs for their monthly Bulletin 120 update.

The data collected by Lauren, Andy, and Gabe highlights the research and operations partnership between DWR and CW3E, where embedded hydrologist Gabe Lewis helps facilitate the flow of data, information, research ideas, and new scientific publications between the two organizations. CW3E’s embedded positions have helped with meteorologic and hydrologic forecasting, data analysis, project synthesis, and field work across the Sierra Nevada. An album of all photos from that day can be found linked here, thanks to DWR’s photographer Nick Shockey.

Andy and Gabe work to unscrew sections of the snow tube after finishing the day’s measurements. (P.C. Nick Shockey, DWR).