How Safe is Your Home?

By Julie Morse, Regional Ecologist

Regulations are often out of date, and may provide a false sense of safety

Question: Honestly, if you had an opportunity to buy a house high on a bluff with an acre or more of forest in the backyard and a river nearby, would the thought of the house someday falling into the river even cross your mind? If you had stood on this back porch 10 years ago and contemplated that question, you wouldn’t have even known a river was nearby, unless you had a map.

Photo © Steve Reutebuch

This house perched above the South Fork of the Stillaguamish River toppled down the bank the day after the above photo was taken.

When we see images like this, it seems so obvious and many of us think, "Well, that was a dumb place to build." And we tend to blame the county or the developer: "Don’t we have regulations that prevent building in unsafe places like this?"

The reality is, no, often we don’t. Even where we do have land-use regulations, many are based on outdated or limited information. And virtually none incorporate future risk that is due to a changing climate. Floodplain regulations, for example, are based on calculations and modeling of a “100-year flood,” yet the modeling doesn’t incorporate climate changes in hydrology or sediment filling up a river bed. Recently, we’ve seen examples where the floodplain regulations are wildly inaccurate — in Houston, 80 percent of the recent flooding caused by Hurricane Harvey happened outside the 100-year floodplain. Locally, the Stillaguamish River has had a “100-year flood” at least five times in the last 10 years.

Regardless, this house wasn’t even in the floodplain and its owners couldn’t have gotten flood insurance even if they wanted to. It is in a "channel-migration zone" — CMZs, as they’re called, are areas where the river will likely meander. We know rivers do roam, and CMZs tell us where the river is likely to go.

Knowing that the house was in a channel-migration zone could have alerted potential buyers to the risk. But predicting the likelihood of that risk more than 10 years out would have been highly variable, at best. Human behavior, generally, is inoculated to unseen risk — our ‘out-of-sight, out-of-mind’ mentality is very strong. Here in Washington state, most of us live in areas of risk — be it from earthquakes, flood, tsunamis, wildfire or erosion like this, yet for many of us that risk doesn’t influence our daily decisions.

Here Today, Gone Tomorrow

Saturday, Jan. 27, one of our staff members, Robin Stanton, took advantage of the heavy rains and high waters and canoed this stretch of the South Fork Stillaguamish River between Granite Falls and Arlington with a few members of the Paddle Trails Canoe Club.

Here’s her description:

“About 5 miles downriver from Granite Falls, we approached the Trangen Meander, a nearly 180-degree bend in the river where an enormous landslide has been developing over several years.

The vacant mobile home was perched on two outcrops of land, the ground beneath it having slid away. Steve Reutebuch snapped a few photos from his canoe as we floated by, marveling at the power of the river to eat away at the land.

The very next day, heavy rains washed away the last dirt holding up the home, and it tumbled down the bank. Q13 had the story."

The Solution: Know Your Risk

While we’d like to think regulations are a safeguard that protect us, the reality is we live in very dynamic landscapes with inherent risks — rivers do roam. For the thousands of us that live near rivers or the coast in Washington, our levees and sea dikes may provide a false sense security. Those thin lines of infrastructure are critical for reducing risk, but they can never eliminate all risk. 

In this rapidly changing climate, past experience (“I’ve lived here for 25 years and it’s never flooded!”) may be a false guide in recognizing the risk. The intense rain we’ve experienced the last few weeks certainly exacerbated the erosion risk. 

And we can anticipate more extreme events like this in the future.  Knowing the local risks where we live, and how those risks could change in the future, is a critical first step in adapting to a changing climate.