Eaton Creek Begins To Dry Up Following 18 Months Of Record High Rainfall

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: