The Nugget Newspaper - News and Opinion from Sisters, Oregon

On a clear day the expansive view of rolling forests to the base of the Three Sisters can tap you into a feeling of the wild. And there is an unusual amount of wild land along Whychus Creek, even outside the designated wilderness. Twenty years ago, during studies of the Whychus Creek Wild and Scenic River, the Forest Service did detailed surveys from town to the wilderness boundary. Specialists found large areas without much of a human footprint. There was no string of campgrounds and few trails along portions of this scenic creek. Just remnant old-growth trees of many species, waterfalls, cliffs, and quiet refuges for common wildlife, including bear, cougar, and birds of all kinds.

Strangely, the reason for this stretch of wildlands was the fear of imminent disaster caused by an interaction of climate change and geology. The "little ice age" was a period of cool weather, which ran roughly from the mid-1400s to 1850. When it ended, things warmed up, and between 1900 and 1940 new lakes were born from glacial melt. Unconsolidated dams of glacial remnants (till, rock, gravel, and ice) held these lakes in place.

It turns out that the Three Sisters and Mt. Jefferson areas have one of the highest concentrations of neoglacial moraine-dammed lakes in the U.S. A U.S. Geological Survey (USGS) report from 2001 noted that moraine dams tend to breech between July and October and result in flows of debris laden flood water. called lahars, which can extend far downstream. (https://pubs.usgs.gov/pp/1606/report.pdf)

That's exactly what triggered the alarm in 1985 when geologists from the USGS became concerned about one particular lake at the base of Prouty Glacier on South Sister, which they predicted could be a disaster for the city of Sisters. Carver Lake contained enough water to fill 370 Olympic-size swimming pools, and a rapid dam failure could inundate Sisters with a lahar flow of water, mud, trees, and rock.

It was a big deal. The governor got involved, there was a task force, and a report with 10 alternatives to save the city of Sisters, including complicated and expensive actions such as draining Carver Lake, or more passive land-use planning to restrict building more houses in the floodplain. The alternative chosen was to build a giant "trash rack" to strain out rocks and mud before it hit town. Unfortunately, the project was designed to be made of wood, which engineers later said would never have enough strength to strain a lahar flow of magnitude. As is the case with many wicked problems, people gave up and forgot about it. The City allowed building in the floodplain. But yellow warning signs were posted in the higher reaches of the creek explaining the danger of creek-side camping. No additional trails or campgrounds were built by the Forest Service.

Community leaders were again concerned in 2007 when updated Flood Insurance Rate maps by FEMA showed that several hundred houses were now within a boundary corresponding to possible flooding in the event of a Carver Lake moraine dam failure. The risk was rated at 1% per year.

Meetings were called to figure out what to do. USGS geologists pointed out that all moraine lakes eventually fail, and that nearby Diller Lake, which is 1/3 the size of Carver, had failed in the 1970s causing a temporary rise in the creek. The idea of sensors at the lake seemed reasonable, but the geologists pointed out that the tricky part was knowing what to do when the sensor went off. Do you evacuate the grade school? Sound sirens? Or did a Canadian goose just land on the sensor? Who was going to go up and look and how much time would they have? No one could fund further study and the issue again faded and life went on.

When Wild and Scenic River planners noted the unusual lack of development along the creek, Forest Service Recreational Specialist Kevin Foss memorably counseled "You can't put wild back," words that inspired the Team. He noted that these wildlands would become ever more important as Central Oregon grew more crowded and people craved the solace of wild places.

With recreation booming, some people wanted trails on both sides of the Whychus from town to the wilderness, with multiple trails for various sports, from mountain biking to horseback riding. However, with a mandate to protect the river's wild and remote character for present and future generations, new standards and guidelines were developed to reduce encounters, limit signs, restrict events, and protect wilder areas from new trails.

The Whychus Overlook was created at the bottom terminus of the Wild and Scenic River, three miles from town. This area was damaged by user-created roads and trails, human-caused wildfires, and vandalism. New signing was minimal and a mostly one-way, barrier-free trail with a few benches was designed to move people along and help maintain that feeling of blissful solitude. The planning team noted that community stewardship was needed to promote understanding of this special place. The wild- lands were left for wildlife and for those who like to wander off the beaten path.

Photo courtesy USFS

Carver Lake looms above Sisters. Potential for flooding has held the community's attention over the years.

The Sisters Trails Alliance picked up the heavy lift of monitoring and maintaining the lower Whychus trails, sanding graffiti from benches, picking up dog poop bags, removing obstacles across the trail, and fixing erosion. They send reports to the Forest Service and consult on complicated issues.

South Sister is a young volcano that occasionally rumbles with small earthquakes that could send rocks and ice chunks into Carver Lake, causing a splash to overtop the dam. But geologists consider the risk of a catastrophic breach to be low. Cougars still haunt the end of the trail, bear and badgers roam, and adventurers can find wild places to renew their spirits. To learn more about Whychus Creek Wild and Scenic River see https://www.rivers.gov/sites/rivers/files/documents/plans/whychus-creek-plan.pdf.