Edgar McGregor

For only the fourth time in recorded history, Eaton Canyon has picked up over 42” of rain in a single winter season. After years of crushing drought and heat, water is once again prevalent in the canyon. Through May 11th, here are the season’s rain totals throughout the canyon:

• Eaton Dam: 42.72”
• Stonehill Neighborhood: 41.44″
• Henninger Helipad: 42.15″
• Inspiration Point: 45.04″
• Camp Hi-Hill: 60.24”

All of this water has helped the canyon turn lush and green for the summer season. Eaton Canyon is technically classified as having a Mediterranean climate. However, much of the vegetation here is more representative of a semi-arid desert thanks to the infrequently but heavy nature of winter storms. Water is not a common occurrence in the park, and so the next few months will be a very unique ecological period for the canyon with water readily available in the creek.

Water in the wash is expected to stick around nearly all summer, and it may be until July before the first crossing even dries up. The waterfall will still have a decent amount of water in it come November, unlike recent years where it was reduced to a trickle. It has rained on 62 days since October 1, 2022, which is more rainy days than any year since 2011. Only 6 other years since 1908 saw more rainy days than 2023. None of the infamous years of 2005, 1980, 1969, 1943, and 1939, which all witnessed exceptional flooding within the park, are on that list. Rain totals over an entire winter are not what causes flooding in Eaton Canyon. Instead, it is short bursts of exceptionally high rainfall over a period of hours or days that has sent 10-foot high walls of water through the park in the past. The 2023 winter, while wet, lacked exceptional storms that would’ve caused major flooding within the park. The storms were well spaced out, moderate, and did not contain extreme rain rates. As a result, minimal damage to the park was done. You can read more on this winter’s impacts here.

All of this heavy precipitation inevitably will grow fuels of wildfires later this year. In shrub-like ecosystems like ours, it is actually years with heavy rains that can see the most extreme wildfires. The extreme wildfire years of 2017, 2018, and 2020 in Southern California were not exceptionally dry years.

On Monday, March 27th, clean-up crews set out to clear an abandoned homeless encampment located ~80 yards up the east trailhead of the Altadena Crest Trail in Eaton Canyon. The encampment belonged to a homeless person found dead of hypothermia in a ditch about 20 yards below the Pinecrest Gate a month prior. No personal items aside from an iPhone were found during the clean-up.

The trash found there included copious amounts of plastic, electronic waste, half-buried bedding, cans of butane, batteries, lighters, and broken bicycles. In all, twenty 50-gallon bags were filled totaling over 1,000 lbs. of municipal waste. Much of the small canyon that the encampment was located in experienced mud flows when heavy rains fell, and some trash may still be buried under the mud. Clean-up crews will return to the location periodically to check for any trash that resurfaces. To the park staff’s knowledge, this is the only encampment in the upper half of the wash. 

In October 1993 during a northerly Santa Ana wind event, a campfire started by a transient along the Mount Wilson Toll Road spread to nearby brush, setting it on fire. While fire officials were busy with several other fires burning throughout Southern California, the fire descended the San Gabriel Mountains and ultimately burned over 100 homes lining the canyon. Homelessness is a continuing issue within the canyon, with over a dozen abandoned encampments having been cleared so far this decade. The county is aware of three other encampments located near the Nature Center that are also abandoned. 

Before photograph by Mitch Marich, after photograph by Edgar McGregor 

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Photo: © Dave Szamet

A powerful Pacific storm made landfall in Southern California on Friday, February 24, 2023, and Eaton Canyon took the brunt of the system. The storm brought a whopping 40″ (3 feet, 4 inches) of snow to Mount Wilson according to the National Weather Service in Oxnard. At the bottom of the canyon, Eaton Dam reported 7.93″ of precipitation for the entire event, bringing the water year’s rain total to 29.73″ of accumulated precipitation. This makes the 2022-2023 water year the wettest rain year in the canyon since since 2005 when 70″ fell in lower Eaton Canyon.

Snow levels were reported to be down to 2,500′ at times, with up to an inch of snow falling at Henninger Flats. Old Pasadena reported 8.11″ of rain, 7.49″ of which fell during 48-hour period from February 24-25th. This makes the 2023 #SouthernCaliforniaBlizzard the 11th wettest 2-day period in Pasadena’s 118 year long weather record book. Flash flooding within Eaton Canyon itself was limited due to low snow elevations and the lack of any particularly heavy downpours throughout the system. It is increasingly obvious that rain rates, not necessarily rain accumulations, are the most important factor for producing dangerous flash flooding within the canyon. The December 14, 2021, January 10, 2023, and February 24, 2023 storms all brought 6″ – 8″ of rain to Eaton Canyon, but that precipitation fell in a much shorter amount of time during the December 14, 2021 storm and resulted in a much more significant flash flood.

Maximum wind gusts included 34 MPH at the Pinecrest Gate, 50 MPH at Henninger Flats, 74 MPH at Mount Disappointment, and 86 MPH at Barley Flats Road behind Eaton Canyon along Hwy 2 in the Angeles National Forest.

The Altadena Mountain Rescue Team (AMRT) reported that 2 individuals were trapped in the canyon after dark on the 25th as the trails were too slippery to hike up. Once again, we do not advise hiking in Eaton Canyon during inclement weather. While rescues happen at all times of the year, rescues are most common in winter when inexperienced hikers underestimate the power of mother nature. Always check the forecast and let others know where you are going and when you’ll be back.

More images of our incredible snowstorm all courtesy of AlertCalifornia webcams:

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