Northern California rivers are moving cooler and faster than normal, officials warn

It's official, the heat is upon us. 

Officials with the National Weather Service in Sacramento are predicting valley high temperatures could reach 103 degrees on Friday, 98 on Saturday and 100 on Sunday. And that’s after multiple triple-digit days this week.

Here's the high temperatures forecasted for the next 5 days. Areas closer to the Delta will get a bit of relief from the 90 & 100 degree temps this weekend, but early next week those very hot Valley temps return. For your local forecast, visit https://t.co/7FMe5tvLcs. #CAwx pic.twitter.com/tcIyYTHNmq

— NWS Sacramento (@NWSSacramento) June 5, 2024

For a lot of people, that means heading to cool and refreshing waterways in order to seek refuge from the heat. There are plenty of lakes, rivers and other watering holes in Northern California, but they can also be dangerous, and drownings are reported every year.

With heat also comes snowpack runoff, and officials across the state are warning that river waters are moving more quickly — and at cooler temperatures — as warm weather accelerates the melt. 

Those cold and fast conditions are the case for one of our most beautiful rivers, the South Yuba River in Nevada County. It’s a recognized California Wild and Scenic River that’s home to some pristine swimming, but it’s also easy to underestimate how quickly the water moves. 

Aaron Zettler-Mann, the executive director of the South Yuba River Citizens League, also known as SYRCL, spoke with CapRadio’s Vicki Gonzalez on Insight to discuss river dangers, what makes this year different from others, and some tips for visitors this summer.

This interview has been edited for length and clarity. 

Interview highlights

Well, let's start off with SYRCL, its history and mission for the South River.

SYRCL is just over 40 years old and it started with a dedicated group of people up here in Nevada County that were really interested in stopping the construction of proposed dams on the South Yuba River, which would have drowned a gorgeous stretch of river that we all know and love today. We were of course successful, and now we have the state Wild and Scenic River Corridor: About 40 miles [of the Yuba River] that we enjoy. Since then we've expanded a lot, we do a tremendous amount of restoration work. We have a Wild and Scenic film festival, education and a lot of community advocacy and engagement.

For someone who hasn't been to the South Yuba River yet, what do you love about it?

I really enjoy the river year round. I'm a big white water paddler. When the water is high and not great for swimming, or you know, picnics, that kind of thing, it's great for white water paddling, rafting and kayaking. It's really lovely in the fall and winter for the trails, for running and just kind of getting out there. Wildflowers in the spring are gorgeous, and of course in the summer, the swimming can't be beat: Big granite boulders, clear and warm water, and everything that makes swimming perfect.

We are in the thick of a heatwave right now across the Sacramento Valley. What are river conditions right now at the South Yuba?

River conditions are high. This is pretty typical for spring: The snow melts and the water swells and river levels increase. We expect things to continue to get higher into the weekend, the hotter temperatures means more snow is melting faster. Right now, the river is running at about 1,600 cubic feet per second, and as we move into this hot weekend, it could be 3,000 or even 4,000 cubic feet per second. So a lot of water is coming down going into the weekend.

Is that a safe environment to jump in and swim around?

No. We’re still early, well before the start of safe swimming season. It's a natural river, it's a natural environment, and so it's never truly safe. There's no lifeguard, rocks are slippery, that kind of thing. But you know, even myself as somebody who kayaks and is a very strong swimmer, spends a lot of time in the river, I'm not really thinking about bringing my dog out or going swimming until the river's down closer to about 300 cubic feet per second or even lower. So, it's hot, I can appreciate that. I'm going to be looking for shade and cool water to swim in this week as well, but the South Yuba just isn't it, yet.

I also follow SYRCL on social media and I've been seeing a lot of PSAs that you've been doing. What is the main message that you want to get across?

The big message this year is stay out, stay alive. And then also stay aware. We had a pretty good snowpack this year, so we are getting a lot of runoff. It's going to continue to be too high to swim for quite a few weeks if not a month. 

This year is a little unique compared to previous years in that some of the power infrastructure on dams upstream — and some of the water diversions that usually help kind of trap that water and divert it into other watersheds for different uses — some of that has been damaged. And so the water level is going to be staying high longer than it usually does because we aren't able to capture it in the reservoirs. 

The other big thing that's different is that we're seeing what's called a diurnal [pattern]. During the day the snow melts as it gets hot. That water runs downstream and it really takes a little bit of time for the water to get from up in the Sierra Nevada down into the river where we're all swimming. What that means is that even when it is a little less risky, the water’s a little warm, it's very likely that folks might get to the river in the morning when the water is low. They wade across [the river] to their favorite beach, find a rock to hang out on, but during the day, because it takes time for that water to move downstream, it's going to come back up and you might not be able to get back across to your vehicle. We've already had a couple of incidents of people needing to get rescued this year. 

Do you have an idea of when you think it might be safe, like later into the summer?

You know, it's really hard to know. It's a pretty natural system and a lot of it is going to depend on how quickly it warms up and how hot it stays. You know, it's warming up, we're in a heat wave. Now if that kind of slows down that might extend that period where it's really high. I think checking the SYRCL website YubaRiver.org, the Nevada County website, there are a lot of resources that you can use to kind of get a sense for what the river’s doing and how kind of the search and rescue community are kind of feeling about access to the river.