Laser measurement of Sierra snowpack from the air being considered in Sacramento

At a price tag of $150 million, the California legislature is considering a bill that, if approved, would change the way the Sierra snowpack is measured each year.

For 90 years the snowpack has been measured at several locations including Phillips, just west of Lake Tahoe. Normally performed in front of media, staff from the California Department of Water Resources (DWR) snowshoe into a spot where they stick a pole into the snow to measure the depth and water content of the snow.

In 1908, James E. Church, a UNR professor at the time, started surveying snow in almost the same manner around Lake Tahoe, a procedure that continues at Mt. Rose, Nevada.

These methods of measuring snowpack may be supplemented by lasers from airplanes.

SB-147 was introduced by California Senator Anna Caballero from the Central Valley and, if passed, would add the "Airborne Snow Observatory," a system capable of measuring snow depths at several points in every square meter of a watershed and would cover over 40,000 miles by air with the use of lasers.

This bill calls for $150M in funding over the next ten years from the state's General Fund to conduct laser surveys via ten airplane trips over the Trinity Alps and the Sierra Nevada each year. They would also fly over hydrologic areas that drain to, or supply water to, certain major reservoirs and lakes. The bill would require the department to collect the aerial survey data and summarize and make publicly available the data obtained and digital products used to produce runoff forecasts.

Existing law requires the California Department of Water Resources (DWR) to gather and correlate information and data pertinent to an annual forecast of seasonal water crop, including the snow survey done monthly in the Sierra at Phillips. That law requires DWR to update every five years the plan for the orderly and coordinated control, protection, conservation, development, and use of the water resources of the state, which is known as The California Water Plan.

Water managers review the collected data to better control water storage, predict drought conditions, while the data also reveals information on tree health, moisture content, and other conditions of California’s forests and watersheds. All of this is critical for targeting key areas where additional forest management and fuel reduction activities can help reduce the risk of catastrophic wildfires, especially under future climate change.

The bill states conventional snow surveys provide useful data to natural resource managers but have limitations, such as inaccessibility of wilderness areas, and result in estimates of snowpack with a margin of error of up to 60 percent.

Caballero's bill says: "When combined with conventional measurements from California’s snow survey program, data generated through the Airborne Snow Observatory has resulted in runoff forecasts that are 96 percent to 98 percent accurate, and this data is already in use by the Department of Water Resources’ flood control forecasters and federal water supply and habitat restoration programs."

They could contract with the National Aeronautics and Space Administration (NASA) to perform the surveys from the air.

The new airborne program would cover areas that drain or feed into Lake Tahoe, Don Pedro Reservoir, Englebright Lake, Folsom Lake, Lake Isabella, Lake Kaweah, Lake McClure, Lake Oroville, Lake Success, Millerton Lake, New Melones Lake, Owens Lake, Pardee Reservoir, Pine Flat Reservoir, Shasta Lake, and Trinity Lake.

SB-487 passed the first committee vote 9-0 and is set for a hearing before the Senate Appropriations Committee on April 22. If it passes it would take effect later in 2019.

Calls and emails into Cabellero's office and DWR were not returned by the time of publication.