Idaho water forecasts have been “all over the board” this year. So what’s going on with predictability models, and why does the water user get pulled down on allotment and then increased? The simple answer is: weather. But the more correct answer is: There are a lot of factors impacting water and water delivery.

Jaynes lynn
Emeritus Editor
Lynn Jaynes retired as an editor in 2023.

One of those factors is population growth. As Idaho’s population continues to climb, so do the number of water users and issues.

“I talked to the manager of a [water] district the other day,” says Paul Arrington, executive director of Idaho Water Users Association, “and he said when he started [years ago], if he got a call for a problem on the ditch, he could just say, ‘OK, I’ll be back in 30 minutes.’ Now it’s ‘I’ll be back tomorrow’ because it just takes all day – because there’s just so much more you have to be involved in and so much more going on. Those are probably some of our biggest challenges that we face [in Idaho].”

Arrington says the expansion in numbers of Idaho water users, however, is just one of many challenges district water managers face today.

Agricultural challenges

Another challenge is predicting water needs in agriculture.


“Farmers start making their plans for the next year long before April. They start looking for seed. And some of them are in multiple-year crop rotations, and so their plans are in place long before we have even a specter of what the new water year is going to look like,” Arrington says. “Some farmers are in a rotation of wheat or others may be in a rotation of potatoes or corn – or whatever the case may be – and those have different demands for water.”

Predicting weather

Another challenge facing Idaho ag users is the predictability (or unpredictability) of weather and its corresponding water supply.

“If we made all of our water decisions in March, we would be missing out on a lot of the water year,” Arrington says. “We can forecast what the water year is going to look like, but when I was at those meetings at the end of March, nobody forecasted that April and May were going to be as wet and as cool as they were. And so the realities are we don’t know until we get it. The forecast in early April provides a pretty reliable target for us as far as what our water supplies may or may not look like for the coming year. But then there’s another forecast in May and there’s some even further into the season. And we continue to forecast what we think the season is going to do. And then we live it, and we change those forecasts based on what we lived.”

Arrington says, “We do a lot of management based on those forecasts, unfortunately. We just have no idea – if we would have made all our plans on January 1, we may have thought we were going to have a gangbusters year. By February 15, we were all shutting the headgates down, and then by April 15 we weren’t sweating quite as bad. It’s difficult. Weather is not as reliant or as predictable as we wish it was.”

Brad Mattson, general manager of the Aberdeen-Springfield Canal Company, agrees and says, “The 30-year median is not the 30-year median anymore. With the weather changing like it is, the weather is just so unpredictable that we cannot seem to predict it even within the last seven days. So we’re having a heck of a time. Yeah, the averages are what they are, but what is an average? Averages include extremes. Our weather forecast has to be at least a little better to manage our system better.”

But things did get better this year, which no one had anticipated in late winter, Arrington says.

“Some districts were able to back off those water restrictions based on the spring precipitation. Early in the season a lot of districts were anticipating again, and they were being told this could potentially be the worst drought on record – that was within the specter of possibilities. And so there were a lot of decisions made where we anticipated cutting the season short – shutting down in mid-August or mid-September – and some were going to cut allocations by half or some even more. Those were the early decisions – some of those made even before a drop of water was in the canals. Then the rains in April and May helped some of those districts to recognize that they could use a little more water.”

“But the reality is: We’re still in a drought. We still have districts, and we still have organizations throughout the state that are going to be shut off. The drought may not be as painful as we first anticipated, but we’re still there,” Arrington says.

Water safety

One of the other challenges we face in a growing state is people not realizing that our water delivery facilities are not recreational facilities to use on a hot day. Arrington says, “Last year, we talked about the 100-degree days, or 90-degree-plus all for June and July, and nothing sounded better than just going and cooling off – taking a dip in some water. And you see these canals and these large water structures passing through our communities, and they’re really inviting. Folks really want to go swim. But they’re not recreational. They’re dangerous. They’ve got swift undercurrents, the water is very cold, and then there are structures, diversion structures and at times even debris under the water that you can’t see.”

Unfortunately, Arrington says, there was a time when Idaho had the unfortunate distinction of having the most deaths in canals in the nation. “And that’s not acceptable,” he says. “And so we have a pretty active campaign every summer, urging people to stay out of the canals – they’re not recreational facilities; they’re equipment, basically, used to get water from one place to the next.”


These issues aren’t necessarily new – predicting weather and water availability, crop needs and in-season changes. However, with Idaho in a growing phase with increasing numbers of users, the wakes of these challenges are certainly magnified.