Real time trail flooding info for selected trails in the cities of San Jose, Santa Clara, Los Gatos, and Milpitas in Santa Clara County, California.
Update: Thank you so much and please keep your flood reports coming. I have the Guadalupe River Trail pretty much nailed down. I’m currently seeking time and dates for flooding on Coyote Creek under 101 (and other locations it might flood).
How This Works
The trail status page captures automated real-time river flow and precipitation data to predict trail flooding at selected locations throughout Santa Clara County. Updates occur hourly from 5 P.M. to 10 P.M, and again from 3 P.M. to 8 P.M. I have to limit my number of daily checks because the weather API I use costs me money. If you would like to support this effort, please browse my Amazon affiliate online store, which sorts various categories of vaguely bike-related merchandise into the previous week’s top selling items at Amazon.
The gory details for each stream
- Guadalupe River: As of this update (Feb 6, 2017) I currently report three locations for the Guadalupe River Trail across San Jose – under Highway 101 at the north end of SJC airport, under I-880 at the south end of the airport, and a vague “downtown” area, which covers the trail where it passes under major roads from San Carlos Street to East Santa Clara Street. I use the USGS stream gauge near Highway 101 to predict flooding for all locations.
During the summer, this gauge normally reads around 5 to 5.5 feet deep. For anything over seven feet, the trail under the Green Island Bridge and Highway 101 is underwater. Because of urban runoff from non-porous paved surfaces, even a few hundredths of an inch of rain is enough to flood the trail under Highway 101. For northbound detours, go east on Airport Parkway to North 1st Street, where you can ride with fast and heavy traffic in reasonably wide and clear bike lanes. The other detour is to continue north on Airport Boulevard past long-term parking, toward the taxi waiting area, and continue through the road barrier onto Ewert Road (yes, bikes are allowed here, I asked). Ewert takes you to where Central Expressway ends at De La Cruz / Trimble. From this intersection you can either go north onto Trimble (but the Hwy 101 overcrossing is not for the faint of heart), or continue west on Central until you hit the San Tomas Aquino Trail.
If the trail is flooded until 101, you can generally count flooding under Trimble Road and Montague Expressway also.
The trail under I-880 floods when the gauge is over about 10.5 feet. Northbound detour: go east on Hedding to 1st Street, where you have 1.6 miles of “share the road” on narrow lanes until you reach the bike lanes at Brokaw Street. Your other option is Hedding to 10th, make a left where Old Bayshore crosses under I-880, then continue north on on the bike lanes on Zanker Road.
Downtown undercrossings are fairly easy to bypass on surrounding surface streets, so I leave that as an exercise for the rider.
I ride the Guadalupe River Trail daily, so the trail’s flooding predictions are probably as dialed in as I can make it. Because the trail prediction is automated, I can’t account for debris (such as the impassable debris pile on the trail under Montague Expressway January / February 2017).
- Coyote Creek: There’s not an official trail under Highway 237, but I report that location because that’s where the stream gauge (operated by the Santa Clara Valley Water District) is located. If you have a favored creek undercrossing that you think I should provide flooding status for, please leave a comment along with flooding date and time information for that location.
- San Tomas Aquino Creek: I post flooding predictions where the San Tomas Aquino Trail passes under Mission College Boulevard and at Great America Parkway. This trail is trickier to predict because the nearest stream gauge is nearly six miles upstream just north of Williams Road, where Stevens Creek dives into a culvert beneath the median for San Tomas Expressway before re-emerging four miles later at its confluence with Saratoga Creek between Cabrillo Avenue and Monroe Street.
- Los Gatos Creek: I track the Los Gatos Creek Trail under Leigh Avenue mostly to express my annoyance that the city designs a parking lot storm drain to dump directly onto the trail. People passing here with anything more than about a quarter inch of rain will get wet here.
Some lower parts of the Creek Trail through Los Gatos can be subject to flooding. I post those as “Vasona Park” on the trail status page. The photo at the top of this page shows the Los Gatos Creek Trail by Charter Oaks between Lark Ave and Netflix HQ.
- Adobe Creek: The city closes this trail during the winter, so I’m not sure it’s worth maintaining this information. Speak up if you think it’s helpful.
- Penitencia Creek: The Penitencia Creek Trail is a muddy, unusable mess during the winter even when it’s not technically “flooded,” but the crossing under I-680 will increase in importance after the Berryessa BART station opens.
- Stevens Creek: The Stevens Creek Trail in Mountain View rarely floods, but it’s an important, heavily used trail so it’s good to know when it does flood. Because flooding events are rare, my data is incomplete so I can use good reports.
Does anyone use that culvert where Stevens Creek flows under I-280 on the western edge of Cupertino?
Resources
California Nevada River Forecast Center
USGS River Flow Current Conditions for California.
Santa Clara Valley Water System Real Time Data (includes stream flows at numerous locations throughout Santa Clara County).
H/T to Roger Weeks who turned me on to this information several years ago and put the bug in my ear about this predictive trail flooding info page.
2/13/2024, ~5:15pm
San Tomas Aquino Creek Trail Scott underpass not advisable with around 6 in of fast moving water. You can easily avoid by going over the bridge on the road though.