El Niño was a bust in Arizona. Here's what it means
Rains came elsewhere, but moisture skips over the parched state, leaving Arizona "a doughnut hole of dry."
- Salt-Verde water projection drop off sharply after dry February and March
- Colorado River expected to give Lake Powell just 74 percent of norm by summer
- Six years in a row Arizona has received less than normal snowfall
So much for conventional wisdom about drought-busting Pacific Ocean weather patterns.
Another Arizona winter is in the books, this one with all the hope that Arizonans usually pin to a typically wet El Niño event, and we can now officially call it a letdown.
The phenomenon caused by cyclical ocean surface warming simply didn't produce the coveted moisture this time.
For the sixth year in a row, the state’s high country produced less-than-normal snowfall. The result is expected to be less-than-normal water runoff trickling toward the Valley.
The same is true for the stressed Colorado River Basin that supplies the other big gush of Arizona’s annual water infusion. Add it all up and it’s a clear continuation of a drought pattern that stretched back beyond the turn of the century.
Let's run down some common questions about what happened this winter and what it means.
Question: Didn't I read that the skiing was great in northern Arizona early in the winter?
Answer: Yes, El Niño got off to a promising start. The Arizona Republic reported as recently as February that some spots were faring well, with water managers even measuring above-normal snowpack in the Verde River watershed at that time.
But we also reported that that was just a snapshot for that moment of the winter, and that unless there was more to come in February and March, the winter would end up below average in total. And guess what?
"Winter kind of ended up here (above the Mogollon Rim) at the end of January," said David Newlin, watershed project director of the Little Colorado River Resource Conservation and Development Area. "It just stopped."
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It's evident in the precipitation charts from federal Snowtel measurement sites arrayed from the Flagstaff area to the New Mexico line. Things looked great going into February, and then the snow quit falling and never restarted.
Q: What does it mean for water supplies in the Phoenix area?
A: Basically, it means the Salt River Project will have to keep pumping groundwater to make up for the lack of river flows if it wants to keep its reservoir levels more or less steady (and it does).
Right now the reservoirs — chief among them Roosevelt Lake — are a combined 58 percent full. That's about where they were this time last year, SRP says, and they've held steady because the water supplier has turned to wells so it can leave river water behind dams.
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The fall-off in expectations for SRP snowmelt was steep at the end of winter, because the forecasters back in February were counting on abundant snow that never came.
At that time SRP predicted the reservoir system would catch 585,000 acre-feet of water from the Salt and Verde rivers and Tonto Creek by the end of runoff season in May — a nice bump above the 30-year average of 535,000. Today, SRP's final seasonal forecast predicts just 343,000 acre-feet, most of which has already come downstream.
El Niño did help out California's Sierra Nevada snowpack, and it seems to have drenched the Pacific Northwest and even poured some rain on the southeastern U.S., said Charlie Ester, water resources manager for SRP.
"We were just in this doughnut hole of dry," he said.
Q: What about the Colorado River?
A: It's complicated, but the greater Southwest's water outlook isn't a whole lot brighter. Northern parts of the basin — in eastern Utah, northern Colorado and western Wyoming — gained some snow in March.
"There were some pretty big decreases in the rest of the basin," Colorado River Basin Forecast Center senior hydrologist Brenda Alcorn said.
Important headwaters, like those in the San Juan Mountains of southwestern Colorado, dried up just like Arizona. The result is that this month the forecast center predicts the river will feed Lake Powell only about three-quarters of its average flows by July.
Lake Powell captures the bulk of what later ends up in Lake Mead, the reservoir that Arizona water managers watch most carefully. But other sources that supply Mead, such as southwestern Utah's Virgin River, also had a bleak month to end the winter.
INTERACTIVE MAP:Tracing the path of the Colorado River
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This is about how things looked at this time last year, too, when weather forecasters were starting to wonder about their predictions for a wetter-than-average spring. Eventually, though, it came in the form of drenching rains in late April and early May, which kept Lake Powell from declining.
Forecasters again project a wet spring, though Colorado state climatologist Nolan Doesken said their confidence isn't as strong this year.
"There's still a lot of spring ahead," he said, hopefully.
As for SRP's low flow projections? They already account for the rain that Arizona was expecting this weekend.
Q: What does it all mean for our water supply?
A: Metro Phoenix is blessed with a high and rising supply of groundwater, thanks in part to the state, municipalities, SRP and the Central Arizona Project all having dumped previously excess water into the ground for storage. So the loss of river water reaching Roosevelt Lake is no big deal for now.
The Colorado River is another matter. The U.S. Bureau of Reclamation recently projected the odds of a Lake Mead shortage declaration for 2018 at better than 50-50, and this winter's snowpack isn't going to improve the outlook. If the government does declare a shortage, Arizona would lose some of its river water, likely cutting off some central Arizona farmers.
Q: How about fire season?
A: It's almost upon us, and the U.S. Forest Service has already posted some areas as having high danger. The fear is for a big burn this year, because there wasn't adequate snow to seep into the forest floor and water the trees.
"Forest conditions right now are as bad as they were before the Wallow and Chediski fires," Newlin said.
If you're new to Arizona, know that Wallow and Chediski are bad words around here. They rank No. 1 and No. 2, respectively, on the state's all-time list, and transformed hundreds of thousands of acres of ponderosa pine forest. They also took their toll on Arizona's water systems, filling reservoirs with ash and debris and requiring extra treatment for drinking.
At the top of Newlin's mind during this dry season, though, is the dangerous brush and tree growth around forest dwellers' homes.
"Despite our best efforts, not everybody is buying into the idea that you've got to clear defensible space around your property," he said. "They need to get on it."