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Groundwater Basin Mapping Technology

Pilot Study to Help Provide Better Map of Paso Basin

Author: Public Works
Date: 9/23/2019 4:22:44 PM

If you see a helicopter flying low to the ground in North County this fall, please do not be alarmed. The County of San Luis Obispo (County) is mapping the Paso Robles Groundwater Basin.

The County will soon have a more complete picture of the Paso Robles Groundwater Basin, which will allow the communities we serve to make better decisions about managing water resources in the future.

Starting in mid-November 2019, the County will join two other California counties in a pilot study through Stanford University and in partnership with California Department of Water Resources and Denmark using innovative technology that could change the way California collects information about groundwater basins. The data collected will also help the Paso Basin Groundwater Sustainability Agencies comply with California’s Sustainable Groundwater Management Act.

What would normally take the County years to survey will only take a few days, thanks to new aerial groundwater mapping technology called the Aerial Electromagnetic Method.

A low-flying helicopter towing scientific instruments will survey the soils below the surface of rural areas in Creston, Shandon and Whitley Gardens. A large hexagonal frame that looks somewhat like a hoop will be mounted with the measuring devices and flown in a back-and-forth pattern at approximately 100 feet above the ground. The equipment bounces a weak electromagnetic signal beneath the ground surface and sends measurements back to receivers on the frame. This technology allows us to collect data faster than ever before, as the helicopter flies at about 50 miles per hour over a 500 mile flight path. Once the data are available, the County will use information from the survey in combination with well data to develop a more thorough understanding of the local groundwater system.

The helicopter could potentially frighten people and livestock as it flies in and out of the Paso Robles Municipal Airport to refuel. The electromagnetic signal is very weak and does not pose a health risk. Experienced pilots specially trained for low-level flying will operate the helicopter and follow Federal Aviation Administration regulations to ensure flights are in accordance with U.S. law.

The video above provides an overview of the Aerial Electromagnetic Method. (Video: Stanford University)

For more information, please visit