As you probably have heard, over the last week a series of events occurred at Lake Oroville — the second largest reservoir in the state — that caused the mandatory evacuation of almost two hundred thousand people living downstream in Oroville and other communities along the Feather River watershed. Just two years ago, the lake was almost empty.
Terra Firma is not directly affected by this situation. The farm is located on the opposite side of the valley, and we get our water primarily from Putah Creek, which flows from west to east out of the Coast range. But we know all about living just below a large dam: Lake Berryessa is just five miles up the road.
Our dam, called Monticello, has a completely different type of spillway than the one that failed at Oroville, causing the problem. Nicknamed the “Glory Hole”, it is a 440 foot tall concrete tube just behind the dam. When the water level in the lake reaches that height, the water simply pours down the tube and exits at the bottom of the dam.
Lake Berryessa was initially predicted to take at least three years to fill after it was built in the 1960s. Instead, it filled up after just three very wet months. Thankfully, the dam held and the Glory Hole spillway worked as designed, despite the fact that the engineers clearly had no idea how the watershed they had chosen to dam actually functioned.
Since then it has operated properly numerous times. However, the dam operators have no control over it once it begins to flow. In certain years this has caused significant downstream flooding around Winters, but nothing even close to catastrophic. (A bigger concern is the fault line that runs directly under the dam — but that’s a different story).
It’s been eleven years since the “Glory Hole” has flowed, so there was some excitement locally last week as the level of the lake began to rise rapidly during the storms. Since it reached it lowest point last fall, Lake Berryessa has risen over 40 feet — mostly since New Years Day. It now sits just below the lip of the spillway, and the next round of storms will almost certainly push it over.
In the last two years, we have run through the entire range of the wet/dry cycle that has characterized California’s climate for thousands of years. We have gone from the driest winter on record to what will likely be the wettest. From praying for rain, to praying it will stop. And we’ve still got over a month of winter left.
Whenever it dries out, there will be lots of work to catch up on. Here on the farm, we’ll be a month or more behind on just about everything — and so will every other farm north of Fresno. We won’t even need any of the water stored in the reservoirs while we’re waiting for the ground to dry.
The close call at Oroville Dam is a dramatic reminder that our state and our nation has lots of work to do, too. We are riding the coattails of 40,50,60 year old critical instrastructure that we should not expect to function forever. And we’re not doing enough to maintain and upgrade it.