Is a Hard Rain Gonna Fall?

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Let me start off by asking, Do any of the Angelenos reading this post remember the drought we were dealing with a few years back? If not, don’t worry about it. Most of the people living in this city have forgotten all about it. We had a couple back-to-back seasons of heavy rainfall in 2017/2018 and 2018/2019, so everybody assumes we’re back to normal and there’s nothing to worry about. This is understandable because folks at the state and local level told us a while ago that the drought was over, and why would you waste time worrying about a problem that’s been taken care of?

Unless, of course, it wasn’t really taken care of.

There was an interesting article in the LA Times recently about how the 2019/2020 rainy season hasn’t been so rainy. In fact, it’s been pretty dry. If we were just talking about one year, it wouldn’t be a big deal. But in the Times story climatologist Bill Patzert asks if the drought we were experiencing earlier in this decade ever really ended.

Is California Headed Back into Drought, or Did We Never Really Leave One?

Patzert points out that, while we had a couple of really wet years recently, over the last 20 years LA’s average annual rainfall has been below the historic average. He makes the case that we’re actually experiencing a long-term drought, and that the recent years of heavy rain didn’t begin to make up for earlier losses. If this trend continues, it would have disastrous effects on our water resources.

Patzert is a very smart guy, and I think we all need to take his warning seriously. I have only one problem with the way he states his case. When people use the word “drought” they’re talking about a period of low precipitation that’s a change from normal levels. But what if this is the new normal? Global temperatures continue to rise.  In California, San Francisco and Sacramento have been growing hotter for decades. While the last decade in LA wasn’t our hottest, it was significantly hotter than the previous one. Scientists disagree on how climate change will affect precipitation in California, but based on the patterns of the past 20 years, I think it’s possible that LA just isn’t going to get as much rain as it used to.

Is this really a problem? How much does LA actually rely on rainfall for its water supply? Let’s review a few basic facts….

LA only gets between 10% and 15% of its water from local aquifers. The rest of it is delivered via massive and complex infrastructure from places hundreds of miles away. While the percentages change from year to year depending on a number of factors, we usually get about 30% of our water from the LA Aqueduct, 30% from the State Water Project, and 30% from the Colorado River. So that must mean that even if we don’t get much rain, we still have plenty of water to draw on. Right?

Wrong.

Actually, all of these water resources are declining. We’re dealing with a whole new reality, and we need to wake up to that fact. Most of the water we get in LA comes from snowpack in the Sierra Nevada Mountains. As of February 18, the California Cooperative Snow Surveys report that the snowpack in the Sierras is at 53% of what’s considered normal. Most scientists who have studied this issue agree that climate change will cause continued decline in the Sierra snowpack through the end of this century, with one group saying we could see a reduction of as much as 79% by 2100. Since both the State Water Project and the LA Aqueduct rely on snowmelt from the Sierras, a decline of that magnitude would be catastrophic for LA.

As for the Colorado River, it’s uncertain how much longer we’ll continue to get the allotment agreed on in the Colorado River Compact. Many decades ago researchers began to realize that the allocations granted to California, Arizona and Nevada under the Compact actually add up to more water than the river can deliver. And since we’ve pretty much done nothing to correct the situation, the water level in Lake Mead has been declining for years.

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In this photo of Lake Mead it’s easy to see how far the water level has dropped in recent years.

So while it’s true that a drop in precipitation for the LA area wouldn’t, by itself, mean disaster, when you combine that with the fact that all our water resources are declining, we’re looking at a pretty desperate situation. That’s why it’s important that we take Bill Patzert seriously when he says we might still be in the middle of an extended drought. And that’s why, instead of just assuming that things are back to normal in LA, we need to start asking what the new normal really is.

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