Oregon Public Broadcasting

A year and a half ago we told you about a plan to collect more water for Oregon’s one of the fastest growing counties. Now there’s a major complication.

As Oregon Field Guide’s Vince Patton reports, county leaders may not be able to build the dam at Hagg Lake any higher. 

They might have to build a whole new dam.

During the summer growing season, Matt Unger depends on two things. Sun and water.

Henry Hagg Lake

Matt Unger: "Basically we wouldn’t be raising these crops without the water."

But the steady supply of water he sprays on his blueberries, strawberries and raspberries is not guaranteed.

Matt Unger: "it’s interruptable water so if there’s a shortage we would be one of the first ones cut off of getting water that year."

He gets his water where much of Washington County does:  Hagg Lake.

Many people think of Hagg Lake as a playground. 

Families and fishermen and boaters flock here.  

But the lake’s primary purpose is to supply water to farms, industry and 400,000 people.  

It’s a man-made lake that fills behind a dam built in the early 1970’s.

Now county leaders are looking at the next 50 years.

Their forecasts predict another half a million people moving in.

Tom Vanderplaat with Clean Water Services says that means they need more water.

Tom Vanderplaat: "We need about another 50,000 acre feet. An acre foot is about a football field covered with a foot of water. So we need 50,000 of  those. Hagg Lake today holds about 50,000 acre feet. We need to double that volume."

A large partnership of cities, the county, irrigators and water suppliers has a solution.

They want to make the dam at Hagg Lake even taller – and back up twice as much water in the reservoir.

However, environmental groups would like to see more done to help fish, because the current dam blocks fish from 40 miles of streams.

So river advocates are pushing for fish passage – but they’re not fighting the overall project  since the artificial lake already exists.

Planners say part of the new water supply would be reserved to increase river flows downstream in order to help endangered fish.

But the water supply project has hit a major snag.

To learn why, we need to jump back to August 2008.

That’s when crews brought in what looked like an oil rig.

It was a drill -- of sorts.  With each powerful pound the machine taps a hollow tube inch by inch down through every layer of the earthen dam -- 165 feet down -- all the way to the bedrock of the valley floor.

The tubes bring soil samples back up.

They must test because no one knows whether this 34-year-old dam could stand up to an earthquake.

Don Stelma is a geologist with the Bureau of Reclamation which owns the dam.

Don Stelma: "What that tells you is in an earthquake event, based on the strength of those soils, how that soil is going to behave under those forces of the earthquake. At the time this dam was designed it was designed for what was an acceptable earthquake at the time in the mid 70’s."

Scientists know a lot more about earthquakes now.

Recent research shows the Cascadia Subduction Zone off Oregon’s coast is likely to produce a catastrophic magnitude 9 earthquake.

The dam at Hagg Lake was built when standards were less stringent.

Don Stelma: "That doesn’t necessarily mean there’s any kind of imminent danger at this point, but you know, potentially, during an earthquake there could be."

Early test results indicate the dam is deficient.

Now planners face a federal mandate. 

They have no choice.

No matter what else happens, Washington County Chair Tom Brian says the dam must be upgraded for earthquake safety, regardless of whether the dam is raised to hold more water.

Tom Brian: "And the big question is do you want to put 3 or 400 million dollars of tax money and not even create a single new drop of water?"

Chairman Brian now thinks a better option is to build an entirely new dam – just downstream of the current one.

The cost would double the price of raising the current dam.  If the water supply project includes building a new dam, the cost is nearly $1 billion.

They’re counting on the federal government to pay 30 to 40 percent of that to cover earthquake safety.

Tom Brian: "Doing nothing is not an option. If nothing else, that dam will need seismic. No one’s in danger now but when you think about the future and their seismic calculations, it needs to be addressed."

The project they hoped to finish by the year 2016 will be delayed by at least several more years.

The dam project is even more complicated – particularly because it has always blocked fish from getting upstream.   Vince Patton explores that tonight on Oregon Field Guide.  It airs on OPB-TV tonight at 8:30.