Century-Old River Gauge Tells A Story

Jun 26, 2012


In the West, people place all kinds of demands on water. Fish and wildlife need this limited resource, too.

Parceling it out requires accurate data about water amounts and levels - That’s why the federal government started to build river gauges 123-years ago. One of the oldest in the Northwest can be found in Idaho.

The Boise River starts as melting snow in the Sawtooth Mountains. It twists and turns through 102-miles of forests, deep canyons, open range, and urban areas to the Snake River.  Along the way, every drop of water serves a purpose.

“How we use the water here has strong implications all the way down to the mouth of the Columbia," says Greg Clark. He’s an associate director at the U.S. Geological Survey based in Boise.

He explains that water found in eastern Washington and Oregon comes from many places, including Idaho’s central mountains. River gauges were installed near the turn of the last century to keep track of all that water making its way to the ocean.

“The irrigators depend on it, we have tribal people that depend on it, the anadromous fish depend on it, the hydro-power is highly dependent on the flows from this system," Clark says.  

Today, there are 688 river gauges in use in the Northwest.

The Twin Springs gauge stands like a sentinel on the bank of the Boise River’s middle fork.

This 10-foot-tall corrugated metal silo has measured a century’s worth of brawling runoff in springtime and icy winter flows. A tube extends down the bank and into the river. It’s gathering data on temperature, flow, water level and pollutants.

Greg Clark opens its door; inside is a shelf with two boxes. One collects and calculates data fed from the tubing. The other transmits that information to overhead satellites.

“This is one of the oldest ones that we’ve got and it’s stood the test of time and the information that's it’s providing is just invaluable and I’ve seen this information published in numerous journals - information from this particular site," he says.  

On this day, Clark and Dave Evetts - who oversees Idaho’s river gauges -- drove to the remote site in an SUV. It’s accessible by a single dirt road.

But it wasn’t always this easy. When it was first constructed - USGS employees had to brave the elements on horseback or in the earliest of automobiles.

“I’ve actually seen pictures of them sitting beside their Model T with bandoliers and pistols on their hips," Evetts says.  "So it was a very different environment but even back then they realized how important it was to keep track of this resource so.”

Originally, stream gauges were established in the West to determine the potential for the irrigation systems -- vital to the economic development of this arid region. The Twin Springs river gauge was built to establish streamflow information prior to the construction of the Arrowrock Dam several miles down river.

Tim Merrick with the U-S-G-S is standing in front of the river gauge. He explains it may not look like much to someone driving by. But the information has been in demand -- especially since 2003. That’s when satellite and internet technology combined to allow people to access the data online.

“So streamflow information from a gauge like this one behind me is used by everyone from the average citizen who wants to come out here on a weekend and go fishing or rafting," Merrick says.  "To agencies like the U.S. Army Corp of Engineers and Bureau of Reclamation who manage the reservoir system here on the Boise River for flood control and for irrigation.”

That information helps meteorologists like Doug Iverson, who forecasts the weather at KPVI-TV in Pocatello. He uses the gauge’s information to let his audience know when the river levels get close to flood stage.

“And so it’s my job again to get that information to them as quickly as possible so the public can make a judgment on what they need to do to protect themselves," Iverson says.  

In recent years, the Northwest’s river gauges have taken on an additional role. They’re being used to help measure the rate of climate change. Scientists can now see the rate of temperature change over multiple years. Greg Clark is with the U-S-G-S.

“We’ve seen a shift in the pattern in the annual runoff and I think that’s what's really interesting," Clark says.  "This is a sentinel site that's showing some things that we might not see in other places or you might not see with a very short period of record. But we can see that since the ’60s and ’70s the water is coming off earlier and it’s melting in the mountain quicker.”

River gauges are telling hydrologists that spring runoff is beginning three weeks earlier than it did four decades ago. That brings serious consequences for the water users and managers downstream. It drives decisions by the U.S. Army Corp of Engineers to spill more water earlier in the year. It means less water for farmers by mid-summer...and it means migrating fish have to delay their annual trip back to their native rivers and streams.

A few months ago, Congress considered ending funding for some river gauges. In the end, it decided to keep all of them operating. Clark says he’d like to think the century old Twin Springs river gauge will be doing it’s job on the Boise River for the next 100 years.