A beginner’s course on how officials determine potential run-off

Sierra Wave Media –

To Eastern Sierra residents, in most years, annual run-off means the streams and canals rise and pasture lands start to green-up. For Los Angeles Department of Water and Power, run-off is the city’s life’s blood, the calculation that figures into the department’s operations for the next 12 months.

In years like 2017, run-off is an all-consuming 24/7 concern.

So, how do they figure it out? Eric Tillemans, LADWP engineer, gave the Inyo County Board of Supervisors a beginner’s course in Run-Off 101 at a recent meeting. Here’s how it works.

Snow pillows are located at each of the major water shed points, Gem and Mammoth Passes, Rock Creek, Sawmill, Big Pine Creek and Cottonwood Lakes. The pillows send the weight of the snow on top of them via satellite to the Department of Water Resources in Sacramento. The snow pillow reports are then put on Water Resources’ website.

More important than the pillows are the three snow courses at the same locations and the eight to 10 measuring points down the length of those courses. The first of February, March and April, LADWP staff trek up to the pillows, stick hollow rods into the snow at the measuring points and weigh the snow-packed rods to determine water content.

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