You've seen lots of rain out the window over the past 10 days or so, and you're wondering what impact the storms have had on the reservoirs that most of California depends on.

Well, El Niño has delivered.

The series of wet storms that began the week before last brought very heavy rain to the upper Sacramento River and Feather River watersheds, which feed the state's two largest reservoirs, Shasta Lake and Lake Oroville, respectively. And the reservoirs are rising fast.

How much rain merits the description "very heavy"?

Bucks Lake, a notably wet locale in the Feather River watershed in the northern Sierra, has gotten 26.12 inches of rain in the past 11 days. Sims, site of a roadside weather station along Interstate 5 north upstream from Shasta Lake, reports a 12-day rain total of 20.72 inches.

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The rain has turned the streams flowing to the big lakes into torrents, and the reservoirs themselves are filling with a speed that's almost shocking after several years of drought.

Graph of Shasta Lake's storage level compared to historical average and to previous wettest and driest years on record. (California Department of Water Resources)

Since March 1, Shasta and Oroville have increased a total of more than 1.5 million acre-feet -- enough water for about 3 million California households for a year.

Storage in Shasta has increased by 874,000 acre-feet; as of Monday morning, the reservoir stands about 105 percent of average for the date -- the first time in more than three years it has risen above its historic norm. The vast lake, which stretches into the upper reaches of the Sacramento, McCloud and Pit rivers, has risen 37 feet in the last two weeks.

The rise has been so dramatic that Shasta is now above its flood limit -- the maximum capacity allowed by federal regulations that require water managers to maintain a certain amount of reservoir space for flood control.

Lake Oroville's storage has increased by 681,000 acre-feet and 60 vertical feet over the past two weeks. By midday Monday, the reservoir had reached 100 percent of average for the date.

Storage in the state's other major reservoirs is also increasing -- though not at the same rate as seen in Shasta and Oroville. A California Department of Water Resources daily report on storage in 46 key reservoirs said Monday that collectively they're now about 78 percent of average for the date. Reservoir levels in the San Joaquin River watershed -- including New Melones, McClure and Pine Flat reservoirs -- are still just one-third to one-half their historic average.

Levels for the state's 10 largest reservoirs at midnight Sunday:

Reservoir	Capacity	Current Storage	Pct. of Capacity	Avg. Storage for Date	Pct. of Average	Storage: 3/14/2015
Shasta	4,552,000	3,582,246	79	3,478,835	103	2,651,852
Oroville	3,537,577	2,491,852	70	2,562,226	97	1,773,853
Trinity	2,447,650	1,099,772	45	1,862,763	59	1,164,330
New Melones	2,400,000	529,444	22	1,485,610	36	600,411
San Luis	2,041,000	969,494	48	1,783,481	54	1,370,719
Don Pedro	2,030,000	1,069,933	53	1,458,866	73	880,037
McClure	1,024,600	265,158	26	546,734	49	88,029
Pine Flat	1,000,000	326,739	33	544,442	60	169,336
Folsom	977,000	673,159	69	578,729	116	573,508
Bullards Bar	966,000	788,155	82	657,318	120	599,250

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