US Army Corps of Engineers
U.S. Army Corps of Engineers Headquarters Website

Corps begins "delicate dance" as possibility of drought looms

Erik Petersen, Willamette Valley Project operations project manager

Erik Petersen, Willamette Valley Project operations project manager

Eugene, Ore. - Last spring, communities across the Willamette Valley watched rivers and reservoirs swell rapidly as a tropical storm delivered historic late-season rainfall. And as some battled flooding—and others the threat of it—the reality was abundantly clear: We had more water than we could handle.

The story this year is quite different. And if you’ve visited a lake or reservoir managed by the U.S. Army Corps of Engineers recently, then you probably already know: we're very dry—nearly everywhere.

I constantly strive to keep our communities updated on our Corps-managed locations—even (and perhaps especially) during years where conditions are less than ideal, like this one.

So, how did we get here? Did we see this coming? What does it all mean? And what do we plan to do about it.

Allow me to explain.

The Willamette Valley is a system

It helps to first see the Corps-managed Willamette Valley dams as exactly what they are: individual parts of a greater system ultimately used collectively to manage water. We operate 13 dams throughout the valley—from Detroit Lake to Cottage Grove, and from Fern Ridge to Hills Creek. 

Our mission is to achieve the best outcome with the dams and reservoirs for our communities, the environment, the fish and wildlife and all of us who live here. For you, for your families, friends and coworkers. For us. (We live here, too, after all.)

History has shown us this valley is an incredibly flood-prone area, and as a result, Congress charged the Corps with building a system of dams in the late 1930s to help protect communities.

Today, we refer to that mission as flood risk management because, while we can’t control floods, we can—and do—minimize the risk they pose. Last year’s spring was a perfect example. The quick actions of the Corps’ team, and the reliable performance of our dams and equipment, saved our communities an estimated $1.8 billion combined in averted flood damages—almost double the amount of money the system saves Oregonians annually.

But while flood risk management is a significant part of our mission, the Willamette Valley system also provides hydroelectric power generation; supports fish survival and wildlife habitat; offers world-class recreation opportunities; improves water quality; and supplies water for irrigation and other uses.

Included in this list of responsibilities is a legal requirement to comply with the Endangered Species Act. The Willamette Valley Biological Opinions require the Corps to release water from our dam projects, as needed, for endangered fish species, helping to further avoid jeopardizing their existence.

As you can probably imagine, with all these competing needs, this system and its operation are incredibly complex. Every move is a tradeoff. You might think of it as a constant struggle to maintain equilibrium—always in flux.

We accomplish a lot each year with the Willamette Valley project, but there’s one major variable that determines what we can do: rain.

This year, we simply didn’t get enough. It’s part of the natural hydrologic cycle that we track and, using the best science available, try to forecast.

Rain deficits mean low inflows

Under ideal conditions, we would see steady rainfall, or a number of bigger rain events spread out far enough from one another, that would top off the reservoirs without the risk of overfilling and flooding downstream. Some slight variation of this pattern is what we experience in most years.

Snowmelt provides some help filling the reservoirs, but the system is mostly driven by rainfall.

Each year, between Feb. 1 and the end of May, the reservoirs fill with rain water. Throughout the summer, conserved water is released to support water quality, temperature and habitat goals, both for tributaries and the main-stem Willamette River. The “conserved” water in the reservoirs also affords summer recreation opportunities. As fall arrives, we begin releasing water to create reservoir storage so we can hold back water during winter (flood season) storm events.

When February came this year, water levels were already lower than normal. During February, March and April, we experienced rainfall that was well below average. As of March 26, for example, the Willamette Valley had received less than 50 percent of its normal precipitation.

We’ve been here before—once in 2001 and again more recently. If you remember the spring we experienced here in 2015, you will likely recall some similarities. 2015 was a drought year.

This year looks even drier.

So why didn’t we see it coming?

While this place is unique in its natural beauty—as we can all attest to—it’s also unique in terms of its weather. Namely, how uncertain it can be.

The models we use to assist us in making decisions about operations can show what conditions could look like 10 days out. But the ocean and the Cascade mountain range, make forecasting weather in Oregon difficult. We manage refill and conservation storage based on historic risk, defined by “rule curves” and make small deviations around risk using smaller forecast windows.  Sometimes we cannot predict reservoir levels until the rain has fallen. This doesn’t allow us to see very far into the future.

Impacts and how we plan to deal with them

Unfortunately, we aren’t expecting a whole lot of precipitation to come our way in the near future. The weeks ahead look dry.

What does it mean for you?

In dry years the lack of water can negatively impact water supply, irrigation, fish and wildlife habitat, and recreation. We’re working closely with our partner agencies, like National Marine Fisheries Service and the Department of Fish and Wildlife, to meet our legal requirements for fish populations. Recreation will likely also suffer some blows from the low rainfall and the COVID-19 pandemic.

As proud providers of top-notch recreation opportunities across the Willamette Valley since 1944, this reality saddens us as much as anyone. We understand that recreation is not only important for our wellbeing and enjoyment but also for our local economy.

To borrow a recent comment from one of our fish biologists: “It’s going to be a tough year.”

Frankly, he’s right. We have the water we were given.

That said, we can manage it wisely. So in addition to tough, it’s also going to be a busy year. We’re going to talk a lot. We’re going to hold a lot of meetings. We’re going to keep monitoring and assessing, meticulously so. And each day, we’ll collect a little more data to help guide the management of our projects accordingly.

What we do now matters more than ever. We understand that, and we take it seriously. These are the decisions our engineers and biologists make in partnership with other experts.

And we have fairly recent memories to keep us hopeful as well. We handled 2015 quite well and even saw good fish returns. We have the successes—challenges and lesson, too—of that year to guide our decisions in 2020. In fact, many of the people managing our projects then are still here.

2015 was a year of tough conversations about tradeoffs. This year, we’re going to meet frequently—both within our organization and with partner agencies—to carefully determine how to best use the water we do have.

Our strong relationships with partner agencies give us the confidence of knowing that we have some productive collaboration coming our way. Good collaboration paves the way for good outcomes—ultimately, for success.

Even while we’ve flexed our operations and staffing in response to the COVID-19 pandemic, we will continue to prioritize the operation of all of our facilities and projects throughout the Willamette Valley.

We still have biologists out doing field activities. We have mechanics, electricians and plant operators continuing to work on site to sustain our missions. We even have some folks manning typically remote facilities, all to ensure the best outcomes.

And all of this, of course, while abiding by the guidelines of health experts to keep our team members safe and healthy.

Don’t worry; we’ll all get through this

One similarity between last spring and this spring? Both were initially dry years. But if there was one thing last April’s rain event reminded us of, it’s that, even in a dry year, things can turn pretty quickly.

At this point, as we inch further into spring, we’re not likely to see a similar event this year. But it does demonstrate just how complex this system is and what it takes to operate it successfully.

I’ve often called it a delicate dance.

It's going to be a very busy year, and we're ready for that. We're going to do what the U.S. Army Corps of Engineers is well known for having done countless times in its 244-year history: make the most of fewer resources.

The Corps has long been trusted to face the nation’s toughest challenges. Right now, as you might have seen, we’re responding to the COVID-19 pandemic by helping stand up alternate care facilities to increase available bed space in states across the country—including right here in our own community, in Eugene.

I encourage you to lean on that example. Let it remind you that people are at the heart of what we do, and that we’ll do the very best throughout this year to minimize the impacts on our communities.

People and communities will always remain our top priority.

Trust in us. Thanks for letting us serve you.