Okay, I’m a water resources engineer and geek. We were having some conversations in the water on Saturday about when San Mateo Creek might break through the berm at Uppers. I said probably that evening — not everyone agreed. After all the berm was pretty high and the lagoon was pretty low. The logic was that if the berm hasn’t broken in the heavy rains so far this year, maybe it won’t.
I explained that the soil moisture reservoir in So Cal, and really throughout the Western US, was almost completely depleted from several years of extreme drought. So, even with the very wet weather we have had since December, all the gentle precipitation was just going toward refilling the soil. But, . . . . . . . . .
When the soil finally becomes saturated, almost all the rainfall will turn into surface flows. And, . . . . . . . . .
I predicted that would happen on Saturday night/Sunday morning. Sure enough, . . . . . . . . .
It happened Saturday night. San Mateo Creek started roaring down the canyon, from the top of the Ortega Mountains down to our favorite beach. Look at the streamflow chart from the US Geological Survey stream gage part way up the canyon. Over Saturday night and Sunday morning, the flow went from about 10 cubic feet/second (cfs) to over 3,000 cfs. That is almost a flash flood. What is more important is that it has not subsided much as of Monday afternoon. Over Sunday night, it went past 4,000 cfs and has only subsided back to about 3,000 cfs. Note: the flow rate scale at the left is logarithmic, so it is not linear–ie, a small rise is actually a huge rise near the top of the graph.
If you look at the Surfline Upper Trestles webcam for January 16, 2023, all you see is hot chocolate (or something worse) out in the water. The berm has definitely broken through.
Now it’s going to be fun to see what transformations take place — new sand bars, new rocks for the reef, new paddle-out channels, new breaks? Maybe at least the new sand give us a slight reprieve from urchin spines while paddling in/out at low tide.
To show you what the rest of the past year looked like, look at the graph below. Dry, dry, dry, dry. It never got over 1,000 cfs until Saturday. Remember that soil moisture reservoir. It acts like a sponge absorbing all the rain until it’s full, then flows right into the nearest water course.
The last time we remember the creek breaking through for any duration was in 2017, when the rock were arranged in the “lagoon,” the channel that lets you paddle out at low tide.
If you are interested, here is the map showing the location of the stream gage.
As for wild animals? In the years when the creek flows, we have found all manner of wild animals on the beach. Snakes. Inland fish. Steelhead trout. Crawdads. Coyotes. Mountain lions. Mule deer. And, even a beaver that probably made its way over the Ortega Mountains from the Temecula area. After all, the San Mateo Creek watershed is one of the last pristine watersheds in Southern California.
With the berm blown out and the bottom changing (it can only get better), we will have have a whole group of new wild animals out there when the swells show up — members of the Trestles Surf Crowd! Drop by, but don’t drop in (on our local wild animals).
Trestles Surf Crowd 
The Crowd’s Backlash