The Bull Run Watershed is a temperate rainforest 26 miles east of downtown Portland. The protected watershed has been the Portland region’s primary water source since 1895. It’s no surprise that the Bull Run is a pretty wet place—it is a rainforest, after all. Portlanders rely on the delicious water of the Bull Run Watershed, so we pay close attention to what happens out there. We depend on partnerships with several federal agencies to maintain monitoring systems that collect data on precipitation and streamflow.
So, what happened in the watershed in 2024? Kristin Anderson, Bull Run Water Resource Program Manager, has the details on what went down—and what didn’t. Spoiler alert: We’re talking about a lot of water and a little bit of Bigfoot.
Between the old and the new
Since around 2014, some different seasonal weather patterns have emerged in the watershed. These include faster transitions from wet to dry seasons, longer dry seasons, hotter summers, and later snow buildup. Most of the last 10 years have included one or more of these new seasonal weather patterns. This means the average weather conditions of the full historical record are different from those of the more recent record.
2024 had a more muted expression of some of these newer characteristics. It more or less took the middle road between the old and the new. Let’s take a quick walk through the statistics.
Water three ways: Precipitation, snow, and streamflow
In January, February, May, June, August, and December, precipitation in 2024 was higher than the historical median. In March, April, July, September, October, and November, precipitation in 2024 was lower than the historical median.
In 2024, annual precipitation was about two inches above the historical average.
January 2024 saw very high precipitation due to the snow and ice event that month. May and June also had higher than average precipitation in 2024. This is unlike many other recent years that had below average precipitation in May and June. June’s high precipitation was largely due to an atmospheric river rain event early in the month. Overall, 2024’s summer precipitation was below average—similar to many other recent years.
The Bull Run’s 2024 snow accumulation was very close to historical averages. We track snow accumulation using three federally funded snow telemetry (SNOTEL) sites. These SNOTELs remotely measure “snow water equivalent” (SWE). SWE is a measure of how much water would be available if all the snow instantly melted.
In 2024, snow began to accumulate later in the year than the historical average. This late start has become typical in recent years, although snow accumulation has often started even later (around a month!) than it did in 2024.
Changes to snowpack levels and timing don’t impact our drinking water availability as much as they do in many other Western cities. That’s because rain, not snowmelt, provides most of our drinking water.
Streamflow in 2024 generally zig-zagged around the historical median. Between mid-June and late October, 2024 streamflow was generally below the historical median.
Many streams and rivers (called tributaries) flow into our Bull Run water reservoirs. For most of 2024, streamflow bounced around median historical values. But during the dry season, 2024 streamflow (purple line) was consistently below average (black line). Although precipitation in June–August was above average, flows were below average. This is likely because warmer air temperatures increase transpiration from trees. This increased evaporation causes a large outflow of water to the atmosphere. That water would otherwise make its way underground to streams.
Temperature, demand, and drawdown
Air temperatures were above average nearly all year, especially in June and July. Air temperatures reached 104°F the first week of July, and the month broke record highs in Portland. Looking back at the streamflow graph, you can see that flows were on a steep decline after the early June atmospheric river. By the end of July, after several weeks of above average temperatures, streamflow was well below average.
In mid-January, there was a large spike in 2024 demand well above the 2019-2023 average. For the rest of the year, 2024 demand was very similar to 2019-2023.
Production demand is a measure of how much water we serve to our customers.
January 2024 saw a large spike in water demand due to the snow and ice event. The cold weather caused many main (pipe) breaks and water leaks. Outside of that spike, water demand in 2024 was very similar to the past five years.
We don’t focus on longer-term averages of demand the same way we do for environmental variables like precipitation or streamflow. Lots of factors impact demand, such as population, water use behavior, the efficiency of water fixtures, and weather. This means comparing current to past demand is not a simple apples-to-apples comparison.
Usable storage in 2024 was close to the maximum level (represented by the "Nominal Full Pool" line) until the end of June, when it began to decline. In late October, useable storage began to rise and was close to the maximum again by mid-November.
Drawdown is when we begin to take more water out of the Bull Run Reservoirs than streamflow brings in. This gradually reduces the amount of water stored in the reservoirs.
In 2024, the Bull Run reservoirs started drawdown at the end of June. That’s about 10 days earlier than the long-term average start of drawdown. In many recent years, drawdown has started even earlier.
Drawdown ends when fall rains begin to refill the reservoirs. In 2024, drawdown lasted until about October 20. That’s about 10 days later than the average end of drawdown but similar timing to recent years.
In 2024, we used our secondary groundwater supply to supplement Bull Run water near the end of the drawdown period.
Average, yet different
A report of things being average kind of stands out in a time when so much around us is vividly in flux.
But that’s our water system for you—somehow always a little different.
Supply-rich during regional droughts.
Full reservoirs in the spring even when there is little snow.
A fire near our drinking water intake that doesn’t cause major water quality issues.
Being average in the oddest of times.
…and…Bigfoot.
Wait, Bigfoot? If that seemed like a quick transition, know that I paused a good long while before deciding to continue. But I’m not sure that a tally of Bull Run oddities is complete without mentioning the stark absence of Bigfoot sightings within the watershed. And times are weird, so why not sink into the weirdness a little, just for a minute? Below is a map of Bigfoot sightings compiled by the Bigfoot Mapping Project. That empty void in the middle overlaps with the Bull Run Watershed Closure Area. To protect the watershed, the closure area is off-limits to logging, mining, and public recreation.
So, what accounts for this lack of cryptid traffic? I can only offer ideas and imaginings. Folks who work at our Bull Run Watershed facilities and those whose work takes them into the woods may have their own stories to tell.
An incomplete list of hypotheses for the Bull Run Bigfoot Phenomen-not:
- Bigfoot is aware of and respects the Bull Run Closure Area and steers clear of the watershed to protect water quality and human health.
- Bigfoot can hide particularly well behind the abundant old-growth trees in the watershed.
- The Bull Run’s protections leave few people—and even fewer Bigfoot enthusiasts—out there to observe Bigfoot’s presence.
- Water Bureau staff see Bigfoot out there often enough, but we don’t have a data-sharing protocol with the Bigfoot Mapping Project.
- The Bull Run is a fiction-free zone, whereas the surrounding landscape is steeped in fiction.
- The opposite of 5.
- Government employees will have none of such foolishness. There is work to be done.
Some mysteries defy intellect, logic, and statistics. Personally, I love that.
With that, I leave you to contemplate the mystery, of Bull Run or otherwise.