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The scarcity of water in some Western states is a very well known story. But what's our water story here in Idaho? How much do we have? Where does it come from? And how does water fit in our rapidly growing region?

Watering Idaho: Bulk Of Treasure Valley Water Goes To Agriculture, Not Urban Development

Monica Gokey
An aerial view of the Treasure Valley helps elucidate the area's water challenges. Development hinges on finding a reliable water supply. From above, landscapes with water look green, while the no-water areas look brown.

Idaho is pretty well off, water-wise, compared to other arid Western states. But as the Treasure Valley grows, different water users are poised to square off over a finite water supply.
Here's the pickle: The population of the Treasure Valley is expected to more than double in the coming decades. And that has urban planners thinking ahead. But while it seems like the Treasure Valley is flush with potential water sources, a lot of that water is already spoken for by the agricultural sector.


Between 80 and 90 percent of all water used in the Treasure Valley already goes to farming, not domestic use. And that's not likely to change anytime soon.

An hour and a half north of Boise, the town of Cascade sits at the base of an enormous reservoir. At its outlet, blue-green water gently gurgles out of a nearby power plant into the North Fork of the Payette River.

Roland Springer from the Bureau of Reclamation oversees the agency's Snake River office. It might sound odd that he's from the Snake, but since the Payette  flows into the Snake at the Idaho-Oregon border, the Cascade dam is under his watch.

"Most of our reservoirs will top out or come close to doing so this year," Springer explains. 2016, it turns out, has been a great water year.

The Payette basin is water-rich. And as the population of the Treasure Valley balloons, it’s easy to look north and think, ‘Water! It’s right there!’

But the water in the Payette isn't up for grabs.

At the top of the reservoir, we look out over 47 square miles of blue. Springer explains where it goes from here.

“So this water travels down the Payette River. And then it joins up with the South Fork of the Payette, and then all that water ends up running through Black Canyon diversion dam, where we raise the water level for a couple canals that feed agriculture down in the Emmett area and downstream.”

All this water is here for a single, faraway purpose:

“The space is for irrigation," Springer says.

Credit Monica Gokey
Boise State Public Radio
The Cascade dam was finished after World War II, making it a relative youngster compared to Arrowrock and Anderson Ranch dams on the Boise River. The reservoir holds water for irrigation needs on the Emmett bench.

University of Idaho law professor Jerry Long has more on the backstory.

“In the West, the agricultural fields are often away from the streams. And the mining is often away from the streams. And so to get it there, you have to divert it and build a canal, which is time-consuming and requires capital.”

Being able to save water through infrastructure like dams and canals was pivotal in how Western states like Idaho were settled.

A hundred years ago, farmers had a hard time getting water when they needed it. That changed at the turn of the 20th century when the federal government established the Bureau of Reclamation. “Reclamation” here means to “reclaim” resources from nature. In this case, to harness the power of water.

“The idea is that we were developing the West, settling the West. We want people out there building dams and building canals and mining and putting in farm fields. Those were our primary goals at that time," Long explains.

Congress passed a number of laws at the turn of the century to lure settlers West. And most of those laws incentivized getting here first. 

“To encourage that sort of activity, we created a legal system that gave (settlers) rights in the water -- pretty much absolute rights in Idaho -- as soon as they appropriated it from the stream and applied it to a beneficial use.”

In legal-speak it’s called prior appropriation, or "first in time, first in right." These laws have changed little in the past century, and they’re why farmers today have some of the most senior water rights in Idaho.

They're also why farmers on the Emmett bench have dibs on water in the Payette.

They were here first, and they claimed it for agriculture.

So while it seems like a booming Treasure Valley is surrounded by potential water sources, like what’s in the Payette system, state water managers aren’t looking in that direction. They can’t. History and law are on agriculture’s side.

And that means growing cities trying to find new water sources to meet their demands, may find themselves swimming upstream.
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Copyright 2016 Boise State Public Radio