SRP releases more water as Arizona flood watches are extended

A new storm system on the way and the ramifications of a cold and wet winter throughout Arizona are being felt.

Flood watches across the state have been extended through Wednesday, with waterways dealing with potential swells.

According to the National Weather Service's Phoenix office, with additional rainfall expected heading into later Tuesday and then Wednesday morning, flooding across the Valley is likely to get worse before it gets better.

"Given that the stream flows are very elevated and this combination of additional rainfall, which is quite significant, in addition to more snowmelt, because we have to remember that the snowpack is still well above average, so more of that snow is going to run off into the different rivers and streams. The situation is probably going to get worse than what it is currently," weather service meteorologist Gabriel Lojero told The Arizona Republic.

Arizona road closures and evacuation warnings

Winter weather conditions have already begun to take a toll on highways in northern Arizona, with a slate of closures already in effect. They include:

  • State Route 260 in both directions east of Payson (milepost 277-283).

  • State Route 89A in both directions between Sedona and Flagstaff (milepost 375-398).

  • State Route 87 northbound in Payson.

  • State Route 64 near the Grand Canyon National Park East Entrance (milepost 244-261).

Additionally, the Yavapai County Sheriff's Office has placed Prescott residents in Granite Creek and Granite Gardens in a "set status," meaning those in the vicinity should be prepared to evacuate because of increased flows on Granite Creek from necessary water discharge from Watson Lake.

Mayer residents along Big Bug Creek off East Stagecoach Trail and in the Chimney Ranch RV Park also have been placed in a "set status" because of rising water levels and should be prepared to evacuate as well.

Multiple flood warnings have been issued by the weather service's Phoenix office along Bartlett Lake down to the confluence of the Gila River as well as the Tonto Creek area.

"That's gonna continue for the next several days, and it might continue through at least early next week, if not longer. We could have these flood warnings extend into the beginning of next month," Lojero said.

Additionally, according to Sgt. Joaquin Enriquez of the Maricopa County Sheriff's Office, the Tonto National Forest has been forced to close several recreational areas because of flooding, specifically the areas of Granite Reef, Phon D Sutton and Coon Bluff.

"All those low-water crossings are going to become flooded for the next several days," Lojero said.

Flood warnings throughout Arizona's high country remain in effect too, with areas of Yavapai and Coconino counties being put on notice.

Forecast: More snow for northern Arizona; rain in metro Phoenix

The central forecast into Tuesday has produced steady rainfall in parts of Yavapai County and northern Gila County, with a good chance of spreading to more areas by nightfall. The weather service predicts 1 to 2 inches of rain on average in higher terrains, possibly even higher in localized areas, with the main batch of rain for the Phoenix area expected after midnight.

In northern Arizona, snow will be seen between elevations of 6,000 and 6,500 feet on Tuesday, with the weather service office in Flagstaff having accumulated 6 inches of "heavy wet snow" so far.

"This means that the moisture content in that snow is quite a bit. Just a rough estimate, it's anywhere between half and three-quarters of an inch of liquid is locked up in the fresh snowfall," meteorologist Mark Stubblefield of the weather service's Flagstaff office told The Republic.

This, combined with the high country snowmelt and already elevated stream flows, could potentially force the Salt River Project's hand to release more water, causing even more serious floods.

"It would require SRP to potentially having to do greater water releases along the different dams. That's why the flooding situation could become a little bit worse as we head into later tonight and tomorrow," Lojero said.

That being said, this incoming storm is well on SRP's radar.

"We are watching that storm very closely. It looks like it will hit the watershed later tonight, early tomorrow. It's a warm storm, but it's also a storm that has snow and rain mixed together, which will do two things: It will add to the snow that's up there in the water shed, but it's also going to melt additional snow and increase the inflows into the Verde River," SRP spokesperson Patty Garcia-Likens told The Republic.

How SRP plans to handle water

"We've had releases going on every day since March 2 in anticipation of just the fact that we have a very active wet winter up until March 2. We had about a million acre-feet of water up in the watershed, and at that point it was the second-highest snowpack in 30 years," Garcia-Likens said. "It's a good thing, though, that we've been releasing this entire time."

SRP's case for it being a "good thing" is that these storms will bring more snow that the utility knows will eventually melt, adding to its reservoirs on the Verde River. That water then needs to be released in order to make space.

"We need to make space, and this is for safety of dams and safety to the public. We need to make sure that those dams are able to take in all the snow that will eventually melt over the next few weeks," Garcia-Likens said.

Not only is it for safety, but that water also gets soaked into the ground and into the aquifer, helping to maintain freshwater sources in urban areas as well as agricultural irrigation.

Put to good use: SRP is releasing stored water. But it's not going to waste

How much water will SRP release from Arizona dams?

"In light of the new storm coming in, we are looking at increasing releases. Right about now, we're at 11,000 cfs (cubic feet per second), but that could increase over the next 24 to 48 hours. It really just depends on how quickly the snow melts and how much snow we get from the storm," Garcia-Likens said.

As of reporting, that number has increased to about 12,073 cfs between both the Bartlett Dam and Stewart Mountain Dam (Saguaro Lake). However, the total inflow is hovering around 7,000 cfs, a decrease from Monday's average of 9,037 cfs.

SRP's main concern, though, is the Verde River.

"It's the Verde system that we're concerned with, so even though it's at 83% (capacity) right now, that's still very high considering the fact that we're going to get a lot more runoff as it gets warmer. We're gonna fill all of these systems by the end of the season," Garcia-Likens said.

When taking a look at the numbers, the total reservoir system, boasting a nearly 2.3 million acre-foot capacity, is currently 94% full. For context, the total reservoir system just a year ago was at 71%.

Bartlett Dam renovations coming to hold more water

Over the decades, SRP has lost "a lot of capacity" to store water on the Verde side of the river due to increased sedimentation. In an effort to help with lost space, SRP is working to "modify" Bartlett Dam in hopes of alleviating those issues.

"We are in the process right now of working with the Bureau of Reclamation to modify Bartlett Dam so that it will hold more water," Garcia-Likens said.

It will take some time, though.

"It's a long process. Over the next 10 years, we hope to modify that dam and make it bigger. If that was up there now, we wouldn't be releasing this water," Garcia-Likens said.

This article originally appeared on Arizona Republic: Flood watches extended in Arizona: Who is affected and what to know