LAKE OROVILLE, Calif. -- Southern California is expected to get much-needed rain this weekend, and Northern California has received plenty in recent weeks. But when it comes to drought relief, it's hardly a drop in the bucket.

Two million gallons of water per minute were being released from one of California's largest reservoirs because it was simply too full.

A California reservoir released millions of gallons per minute CBS News

Carl Torgersen of the Department of Water Resources says a so-called "March miracle" of heavy rain fueled by El Nino has filled many of northern California's lakes.

"This reservoir has risen about 216 feet since December and 97 feet in the month of March alone," Torgersen told CBS News.

Five months ago, the reservoir was a nearly empty Lake Oroville. Walls of dirt were hundreds of feet high, and bridges were suspended in the air.

Lake Oroville five months ago CBS News

Now, the water line has climbed. It's still rising thanks to snow melting in nearby mountains -- California's snow pack is the deepest its been in five years.

At the same spot last year there was no snow to measure. Snow melt provides a third of California's drinking water and irrigation for the largest farmland in the country.

But California is not out of the woods yet. NASA senior water scientist Jay Famiglietti says the state's total water storage deficit is 13 trillion gallons.

"To replace that kind of storage, we need a winter like this and three or four just like this, if not even wetter than this one. So we are definitely not out of the woods."

Which is why California is praying for another miracle this month.