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Science and Innovations

Salt River Project Reservoirs Two-Thirds Full Despite Dry Winter

Salt River Project

Winter runoff into the Salt and Verde rivers was the second driest in more than one hundred years of recordkeeping. But the reservoirs that serve the Phoenix area are still two-thirds full. KNAU’s Melissa Sevigny spoke with Salt River Project spokesperson Christa McJunkin about the city’s water supply, which comes from the Salt, Verde, and Colorado rivers and from groundwater.

The Salt River Project’s numbers show that this year was the second driest on record, can you talk about that?

It’s been a shockingly dry year…. Luckily our system is situated that one good year may not fill it entirely but it can fill it up enough that we can live off that extra for several more years. Even though we’re at such at critically low year this year, our reservoirs are still around 67% filled…. It just shows how variable our system can be, and we have to be prepared for both conditions. I jokingly say that water managers are never happy, we either have two much water or not enough.

What are the big questions people are asking about water right now?

A lot of the questions that I’m getting, is how well prepared we are for the upcoming or the expected shortage on the Colorado River. That’s where a lot of people are focused, and with good reason.

What is your answer to that question?

As surprising as it may be for some folks to hear there’s going to be or likely to be a declared shortage on the Colorado River, it’s really not coming a surprise to folks who have been managing water. Really since SRP was founded, our entire history has been based on trying to adapt to this arid desert environment. Our original job, and continues to be our mission today, is to take water supply that can be highly variable and turn it into a dependable source… So this doesn’t come as a surprise. It’s certainly not welcome condition. But it’s something we’ve been, as a community of water managers, preparing for, for many years.

Talk to me about where we’re at with groundwater supplies and specifically tell me about this idea of safe yield, what is it?  

Safe yield as a concept was part of the Groundwater Management Act of 1980 which created five active management areas in the state, the phoenix active management area being one of them. And the goal of all of the regulations that we have are to produce a condition called safe yield. The basic idea is that we want to preserve our groundwater as our drought supply. We don’t want to rely on it as an everyday supply. We want it to be there when we need it to supplement us in times of drought. So the idea is that you want to protect it, and the way to protect it is to balance the water coming out with the water you’re putting back in, either naturally or artificially.

How are we doing with that in Arizona?

That’s a little bit open for debate…. When you look at the long-range numbers, the headline should be how far we’ve come…. In 1980 when the Groundwater Management Act was passed, forty percent of the water used in the valley came from mined groundwater, meaning this was groundwater being pumped out and not put back in the ground. Today, the recent average is 5%. We have come a long way.

Christa, thanks so much for speaking with me.

Sure thing, nice to meet you Melissa.


Melissa joined KNAU's team in 2015 to report on science, health, and the environment. Her work has appeared nationally on NPR and been featured on Science Friday. She grew up in Tucson, Arizona, where she fell in love with the ecology and geology of the Sonoran desert.
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