Does California have enough water yet? [March Update]
After the atmospheric rivers, cyclone bombs, and devastating flooding, has California emerged from its mega-drought? Here are the 4 metrics to watch and where they stand.
In this special edition, we break from our typical format to walk through the 6 metrics that matter to the state of California’s water.
March 22 Update
On January 17, we answered the question of whether California had received enough rain and snow. Our answer was: We’re making good progress, but no, we’re not there yet.
Now, 2 months after our initial analysis, the answer has changed. Watch the video below or read the summary beneath the video to see where we stand as of March 22 on 6 different metrics.
US Drought Monitor:
Percent of state considered to be in drought: 95% on Jan 17 vs. 36% on Mar 20
Percent of state coming out of drought: 5% on Jan 17 vs. 19% on Mar 20
Percent of state not in drought: 0% on Jan 17 vs. 45% on Mar 20
147% of historical average for this time of year
114% of total rainfall received in water year, which runs from October 1 through September 30
225% of historical average for this time of year
218% of total for snow season (amount on April 1) compared 120% of April 1 amount on Jan 17
Collective water levels of 16 primary reservoirs: 52% full on Jan 17 vs. 73% full on Mar 20
Collective water levels of 16 primary reservoirs compared to historical average: 88% of historical average on Jan 17 vs. 104% of historical average on Mar 20
Percent of groundwater aquifers below level: 64% on Jan 17 vs. 62% on Mar 20 (however, most groundwater levels are only measured twice a year, once in the fall and once in the spring)
Percent of rainfall/river levels in Upper Colorado River basin compared to historical average: All sections are above 100%
Percent of Colorado not in drought: 40% on Jan 17 vs. 63% on Mar 20
Water level of Lake Mead: 28%
Water level of Lake Powell: 23%
How Do Know When We Have Enough?
There is no universally accepted definition of droughts because every region and even locality relies on different water sources. As a result, different localities will define droughts based on the status of the water sources that matter to them.
Further, the U.S. Drought Monitor blends 4 different indexes, consisting of soil moisture levels, streamflow, precipitation, and temperature data to score regions across 5 levels of drought. The U.S. Drought Monitor currently classifies 5% of California as coming out of drought with the other 95% of the state either in moderate or severe drought and no regions of the state in the two worst stages of drought.
While this suggests that we still need more water, it doesn’t tell us the state of our water sources and storage and whether we’re on track to get more of the state out of the drought classification.
We have 2 key water sources. Rain and snow provide 200 million-acre feet (MAF) of water every year, 2.5 times our annual water usage.
Rainfall: Very Strong
Rain replenishes our rivers, fills our reservoirs, moistens our soil, and fills our groundwater aquifers/wells.
In this water year (which started in October), we have received 167% of the historical average and 73% of the average amount of rain received for the whole water year. You can see below that we have surpassed 2 of California’s wettest years in history already:
California also pulls a significant amount of water from the Colorado River, which has been very low in recent years as well. However, rainfall in the Upper Colorado River Basin is currently exceeding historical norms and 40% of Colorado is drought-free compared to 0% last year this time.
Snowpack: Very Strong
Snow is important because it feeds our rivers and reservoirs in the summer when it melts, helping refill these water sources as their levels begin to dip. Most of the snowpack is in the northern and eastern parts of the state.
We currently have 247% of the normal snow water equivalent for this date and 120% of the April 1 historical average. This means we have 20% more snow right now than we typically do at the end of winter. An added benefit is that our snowpack is most above historical averages in the Southern Sierra region, which can help source Southern California this coming summer.
Similarly, Colorado’s snowpack - which is a major source of the Colorado River - was at 127% of the median level last week.
There are 2 main ways we store water in California: reservoirs and groundwater aquifers/wells.
Reservoir Levels: Moderate
These historic rains are valuable because California has an extensive system of 16+ reservoirs that can store 23.6 MAF of water. To put this in perspective, California uses 80 MAF per year on average, with the following allocations:
Environment: 40.5 MAF (water for “wild and scenic” rivers, required Delta outflow, instream flows, and managed wetlands)
Agriculture: 31 MAF
Urban: 8.3 MAF (includes residential, commercial, industrial, and large landscapes)
Currently, our reservoirs are collectively just over half full, which puts us at 88% of the historical average for this time of year. Almost two-thirds of our reservoirs have levels above the historical average. If we continue to receive the same amount of rain, we could reach our historical average by next week.
This is good progress and it would likely be sufficient if we could count on similar or even average rainfall next year - but we can’t. Instead, we should aim for 3 year’s supply, which would likely require reaching 90%+ full.
For example, Lake Shasta was nearly full in June 2019, but by October 2022, it was only a third full.
Lake Shasta has risen by ~1 MAF since its low point on December 1. We need it to rise another 2.2 MAF in the next 2.5 months in order to get near the 90% level. Three of the next 4 biggest reservoirs are in a similar position to Lake Shasta. Filling all or any of them this winter seems unlikely.
Groundwater ends up getting stored in underground aquifers and wells, which supply water to many of the more rural parts of California, including much of the Central Valley where most agricultural production happens.
The latest data shows that 64% of wells are below their normal level, but most well levels are measured just twice a year - in October and April. If you look at just wells measured in the last 30 days, only 35% are below normal levels (however, this included just 51 of the 3,500 wells). If you look at wells measured in the last 60 days, 56% were below normal levels (which includes 413 wells).
We’re trending in the right direction, but we’re still not in a strong position relative to historical norms. We’ll know more when the majority of measurements take place in April.
Flushing Water into the Oceans: Moderate
There has been considerable controversy during our recent dry years over the allegation that state leaders are flushing much of our stored water out to the ocean for a variety of environmental reasons. There are 2 places where this controversy focuses: dam releases and the Sacramento-San Joaquin Delta, which flows into the San Francisco Bay.
Releases from Shasta Dam (the state’s biggest reservoir) have been historically low during these storms:
This is a good sign that we are keeping water in our reservoirs.
The Delta is the place where the Sacramento and San Joaquin rivers meet and the hub of the state’s 2 water projects: the Central Valley Project and the State Water Project. It accounts for 30% of the state’s uncaptured water. Unfortunately, roughly 95% of the water flowing into the Delta is being flushed out into the ocean (see raw data) - for a variety of reasons: some good and some more questionable.
Last week, Californian Republican Congressmen sent a letter to President Biden and Governor Newsom urging them to stop existing “flush provisions” that govern how much water is directed through the Delta to the ocean:
“Government regulations should not and must not deny our constituents critical water from these storms. While we cannot make it rain, we must take advantage of opportunities to store water when it does and maximize what can be moved at all times through the Delta for the duration of these storms.”
Other places in California, like Los Angeles, are similarly watching as much of this rainwater drains out to the ocean. In Los Angeles County, they only expect to capture 20% of the rainwater because of a lack of adequate infrastructure.
Do We Need More Water?
Yes. We are not in the clear yet, despite the damage done to several parts of the state. Most of our biggest reservoirs are still too low and too many of our wells are still not full enough.
Let’s hope for more rain and snow (without the toll on human life and property) - but we also need to ask ourselves: what could we be doing to capture more water?
There is an increasing set of technologies we could invest in to strengthen our water infrastructure so that when it rains, we can take maximum advantage of the water we receive. Several questions remain: Which ones should we invest in? At what scale? And perhaps most importantly, can we overcome political challenges to bring these projects to reality?
In this week’s normal Friday article, we’ll evaluate the proposal to build Sites Reservoir.
If you haven’t yet, subscribe for free to receive Friday’s article in your inbox
It likely hasn’t included the present period on this list because it has not finished.