Edgar McGregor

On Saturday, July 20, 2024, the Altadena Mountain Rescue Team (AMRT) responded to four separate incidents involving injured hikers at Eaton Canyon. According to the team’s Instagram account, three individuals suffered severe ankle sprains while another required assistance due to heat exhaustion. The temperature in downtown Pasadena reached a high of 99°F.

In one particular case, a senior citizen slipped down a five-foot scarp in a hazardous section of the trail leading to the main waterfall. This spot is frequently eroded each winter by a hidden watercourse that merges with Eaton Creek just 15 feet downstream from the water mining bunker. The Eaton Canyon Trail segment between the Chuck Ballard Memorial Bridge and the main waterfall is not considered an official trail by the Angeles National Forest. As a result, it is completely unmaintained and subject to far more hazards than most trails.

Eaton Canyon is one of Southern California’s most popular hiking trails, but it is also one of our rockiest. There are ten river crossings that separate the waterfall from hikers beginning their journey at the Nature Center. In an attempt to stay dry, many hikers will hop across rocks in the creek to get to the other side. This is not advised as many rocks are both unstable and slippery from other trail users. Always bring the proper amount of water, foot ware, and clothing when hiking in the Angeles National Forest.

Near sunrise on the morning of Sunday, July 14, 2024, a monsoon thunderstorm developed in the Los Angeles Basin and quickly moved north-northwest directly towards the Angeles National Forest, including Eaton Canyon. Over 50 lightning bolts were recorded by the National Weather Service south and east of Hwy 2, including 18 that struck the Earth’s surface. The storm was responsible for 0.04″ – 0.19″ of rain throughout the local foothills, as well as a 39 MPH wind gust at the Henninger Helipad weather station. In one neighborhood near Eaton Canyon, a lightning bolt struck a power pole and lit in on fire.

Right around 5:50 AM, another lightning bolt struck Eaton Canyon directly, hitting well above the Chuck Ballard Memorial Bridge. Witnesses to the event say the lightning ignited brush in steep terrain. 9-1-1 calls immediately began coming into the Altadena sheriff’s station. Heavy rain soon followed the lightning strike, extinguishing any possible wildfire ignition that may had occurred. By 6:15 AM, the Altadena sheriff’s station had dispatched units to drive around Altadena Dr. to search for smoke and flames. Different witnesses overlooking the canyon at the Midwick gate at 6:24 AM did not see either, and the search for a fire was eventually called off.

Before the arrival of humans, virtually all of Eaton Canyon’s wildfires were caused by lightning. Photographic evidence of an ignition could not be obtained, and as a result, a fire in the canyon remains unconfirmed.

The monthly Eaton Canyon conservation group spent Sunday morning clearing invasive castor bean plants from the wash section directly adjacent to the overflow parking lot. The group had a clear view of the area impacted by the lightning strike, and no additional smoke was ever seen. 

As of the July 1, 2024 survey, 99.5% of Eaton Creek is flowing between the main waterfall and the New York Street Bridge. The remaining 0.5% accounts for the last 60 feet before the bridge, which have dried up in recent days. This marks the lowest flow rate since the December 1, 2023 survey, when the creek was flowing through 58.3% of the park. Eaton Creek’s course spans 2.23 miles from the main waterfall to the bridge, though this distance can vary over decades due to flash floods altering the creek’s path.

August 1 update: As of the August 1, 2024 survey, only 68.2% of Eaton Creek is flowing below the first waterfall. This loss of 31.3% of the creek length in one month is the largest 1-month loss in the data set. This is 25.5% less than on this date last year and comparable to the October 1, 2023 survey. The next survey is scheduled for Sunday, September 1, 2024 at noon.

Since January 1, 2023, a monthly survey has been conducted to examine where the creek is and isn’t flowing. Since it is indicative of the available ground water, the dates at which Eaton Creek dries up at various locations is a better indicator of current drought levels than rainfall measured by automated weather stations. Three inches of rain in 24 hours will have a much better chance of soaking into the ground than three inches of rain falling in 90 minutes. Eaton Creek provides water for many riparian ecosystem critters throughout the park as well as mammals such as deer, bears, and bobcats. A monthly survey is delayed if it is actively raining during the typical survey time (noon on the first of each month) until 48 hours after the rain ends.

Between October 2022 and April 2024, the official weather station in Pasadena recorded a whopping 72.74″ of rainfall, the highest 18-month (540 day) total in 117 years of weather record keeping. This beat the previous record of 70.95 inches held by the period ending April 2006. What sent 2022-24 numbers over the top was the extremely unusual landfall of Tropical Storm Hilary, which made a direct hit on Eaton Canyon on August 20, 2023. Over half a foot of rain fell on the canyon during the tropical storm, making it both the wettest August on record and the wettest summer on record. A similar situation is not expected this year due to La Nina, an episode of cooler-ocean temperatures in the east Pacific that inhibits hurricane formation in the area.

Percent of Eaton Creek flowing between the first waterfall and the New York Drive bridge:

Year	Jan	Feb	Mar	Apr	May	June	July	Aug	Sept	Oct	Nov	Dec
2023	100%	100%	100%	100%	100%	100%	100%	93.7%	89.7%	66.8%	60.1%	58.3%
2024	100%	100%	100%	100%	100%	100%	99.5%	68.2%	51.1%	48.0%

---