Portrait of a Drought: Lake Oroville

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The further adventures of a California reservoir. A year and a week ago — late March 2013 — Kate and I camped in the very nice Loafer Creek campground at Lake Oroville State Recreation Area. The lake, the main reservoir for the State Water Project and the second largest California reservoir after Lake Shasta, was about 85 percent full at the time. If you were following the vagaries of the state’s water season, you might have been a little troubled by the fact the 2012-13 rains had virtually disappeared after the turn of the new year. What wasn’t apparent during the first visit up there was that the rains wouldn’t return in the fall, either, and that the lake would fall to just one-third full by January — low in any season, but especially alarming in that the reservoir levels here and virtually everywhere else across the state continued to decline at a time when they’d usually be filling up with runoff from winter storms.

I drove up to Lake Oroville on January 18, which happened to mark the lake’s low point during the current water year (July 1, 2013-June 30, 2014). The difference in the lake’s appearance was dramatic — see the slideshow below. But when seasonal rains finally returned in early February, the lake began to rise. One way of measuring lake level is the height of the lake surface above sea level. When full, Lake Oroville’s surface is 900 feet above sea level. When Kate and I visited in March 2013, the surface level was 860 feet; when I went back in January, it stood at 701 feet according to the numbers from the state Department of Water Resources. The same source shows the lake at 759 feet now and rising.

Yesterday, Thom and I drove up to Oroville to take a look and take a new set of pictures to show the change since January (they’re incorporated into the slideshow). My impressions:

I suppose this is a “glass half-full/half-empty” exercise on a grand scale, especially since the lake is at almost exactly 50 percent of its total capacity right now. On one hand the lake is up almost 60 feet from the last time I saw it and has added about 40 percent to its storage — it’s added about 500,000 acre-feet since January, enough water for about 1 million California households. More water is coming, too: Even though the forecast for the next couple of weeks and beyond looks pretty dry, and even though we’re nearing the tail end of the rainy season, the snowpack will start too melt and run down the branches of the Feather River that flow into the lake.

The conventional wisdom is that half of the state’s stored water is captured in the Sierra snows that wind up in streams, rivers and reservoirs. One slice of Lake Oroville history shows how dramatic an impact the snowpack can have:

A drier-than-normal water year in 2008-09 reduced the reservoir’s storage to a shade more than 1 million acre-feet, less than 30 percent of capacity, and lowered the surface to 665 feet above sea level by early January 2009; that’s about 20 percent less water and about 45 feet lower than the level we saw this past January. Then storms began arriving and began building the northern Sierra snowpack. The water content of the snow in the Feather River drainage reached about 130 percent of normal by early April 2010, and the lake had come up to virtually the same level as it is this weekend. The reservoir, which had reached its lowest point on January 11, kept rising through June 29, when it reached its high point of about 2.7 million acre-feet and elevation of 843 feet above sea level. That’s a rise of 178 feet in less than six months.

So that’s the glass half-full. It’s normal for our reservoirs to rise and fall, often dramatically (and no, I’m not addressing here the impact of how the reservoirs are operated — how much water is released, when, and why).

Here’s the empty half of the glass for Lake Oroville: This year, the Department of Water Resources estimates that the water content in the thin layer of snow in the Feather River watershed’s high country is just 13 percent of average for this time of year. Thirteen percent. So, we’re not going to see any late season rise in the lake. More likely, we’ll see a scenario more like the one that unfolded in 2007-08, when two drier-than-normal years left the lake at close to the same level we see today — 753 feet. The watershed’s snowpack was lower than normal, and although runoff gave the lake a boost, it topped out at just 760 feet and 50 percent capacity in late May. That dry rain year was followed by another, and in February 2009, the state declared a drought emergency.

None of this is meant to make a single reservoir, even a big one like Lake Oroville, seem more important than it really is. But reservoirs are important to making it possible for 38 million people to live, and for a rich agricultural industry to thrive,in a place where it typically doesn’t rain much for six months of the year. And Lake Oroville’s water storage happens to mirror what’s happening with the state’s water supply picture as a whole at the moment: The Department of Water Resources’ daily summary of 44 key reservoirs shows them collectively at 64.4 percent of average for today’s date. Lake Oroville is at 65 percent.

Here’s the revised slideshow:

Slideshow: Lake Oroville, Before and After

Thanks to the miracles of software and the Internet, I put together a short slideshow comparing scenes at Lake Oroville as I shot them late last March and yesterday. If I’d known back then to what extent the lake would empty out, I would have taken pictures all along the shoreline. As it was, the pictures I did take of the lake were an afterthought, something to do before we started to head home.

The big surprise in the “after” pictures, the ones I took yesterday, is the landscape revealed by the receding waters. There’s no hint looking at the surface in March what the underwater topography looks like. And it’s amazing looking at the exposed landscape now (it was drowned in 1969, when the new reservoir was first filled) and how completely it’s been scoured of anything that might suggest that before Oroville Dam was built, these were canyons choked with oak, pine and brush.

Here’s the slideshow which includes a few bonus shots at the end):

Lake Oroville, Pre-Drought and Now

Kate and I went up to Lake Oroville for a couple days last spring. We found a great campground on the south side of the lake, which is the main water storage facility for the State Water Project and at 3.5 million acre feet, California’s second biggest reservoir (Lake Shasta, at 4.5 million, is No. 1). Our real purpose was to go further up into the foothills for a hike out to a falls we had read about. But before we headed back home, I took a few pictures down around the boat ramp nearest our campground, in an area called Loafer Creek.

Before I drove back up there today, I checked the Department of Water Resources data for the reservoir level both on March 27 last year, when the top picture was taken, and today. The numbers show that despite the dry second half of last winter, the lake was about 85 percent full on the day I was taking pictures. The elevation of the lake surface above sea level was reported at 860.37 feet, and, with the help of a couple of small storms that blew through in April, the lake level kept rising for the next several weeks, with the surface topping out at 871.75 feet above sea level.

In the current water year, which for the Department of Water Resources runs from Oct. 1 through Sept. 30, Lake Oroville has seen 2.44 inches of rain. Just a guess: that’s about 10 percent of average for this date. Of that 2.44 inches, 1.96 fell on Nov 19th and 20th. The last rain was recorded Dec. 7, six weeks ago today. Not a drop has come down during the weeks that are typically the wettest of the year in this part of the world.

Which is why I went to take another look. The lake’s surface elevation today — drawn down by 10 months of water releases to generate power and send supplies down to the southern end of the Bay Area, the San Joaquin Valley, and those big cities far to the south — now stands at 701feet, 159 feet below where I saw it last time. That’s roughly 35 percent full. I wondered how dramatically different it would look.

The truth is that if I didn’t have the earlier set of pictures and some fixed landmarks, I would have hardly recognized it as the same place. Here’s one example (and here’s the full Flickr slideshow: Lake Oroville, January 2014):

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Lake Oroville at Loafer Creek: March 27, 2013

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Lake Oroville at Loafer Creek: January 18, 2014