Reservoirs near winter-time capacity: What that means

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BOCA RESERVOIR, Calif. (KOLO) The rules that manage the Truckee River system mandate that enough room be left in upstream reservoirs to handle potential winter-time floods. As of January 8, 2018, those reservoirs are almost at the maximum levels allowed during the winter. Tahoe is almost full and only Boca has a little room left and in the next few days it will be at that maximum level.

When that happens, any water added there or elsewhere in the Truckee system will be passed through, sent downstream.

"When the river gets above a certain point, which is 6,000 cfs (cubic feet per second), we have to shut the releases off,and fill that empty space," says Federal Watermaster Chad Blanchard. "If it's below 6,000, which it is unless we're flooding, then we have to just pass that water through and let it go down."

So as rain falls in the Sierra we may see the Truckee running higher than we may be used to seeing it this time of year.

"It's really good for Pyramid Lake but it doesn't do much for our water supply."

It is--he notes--a good problem to have, though; if our snow pack continues to be anemic, it could leave these reservoirs with less than they might have had come spring.

"So we want to see the snow pack build because that's our biggest reservoir. That is pretty dismal at this point. So the reservoirs are good, but the snow pack is not good, which means in the spring time when it comes time to fill that flood space and top off the reservoirs, if we don't have enough snow we can't fill them up."

And though we'd like to have all the reservoirs filled come the summer, last year left us with plenty to get by for the next few years.

This is all true for the Truckee. The Carson River system is much different. With no upstream storage it's totally dependent on the snow pack which so far, is--as we said--anemic.