SANTA CRUZ >> Big storms and long periods of rain from a predicted El Nino winter in Santa Cruz could bring floods to low areas near waterways, city leaders said this week.

Two maps made by the Federal Emergency Management Agency, show the potential of a 100-year storm. If water were to breach the San Lorenzo River levee, it would flood downtown Santa Cruz from Pacific Avenue past Chestnut Street to the Santa Cruz High School playing fields, according to the maps.

Homes also are vulnerable to floods on the lower part of Arana Gulch, north of the Santa Cruz Small Craft Harbor, parts of Branciforte and Carbonera creeks and the lower part of Moore Creek on the far Westside, city leaders said. Other vulnerable areas include the Beach Flats and Lower Ocean neighborhoods, as well as homes and businesses between River Street and the San Lorenzo River.

The chances of a San Lorenzo River levee breach are not great, said Santa Cruz Public Works Director Mark Dettle. But he noted that it’s been at least a decade since sediment has been dredged from a collection spot south of the Highway 1 bridge. The river’s flow slows there and sand tends to collect, raising the water level during heavy rain.

“It’s a concern if we get these extreme events,” Dettle said.

City leaders have been working with the Army Corps of Engineers for 15 years to redesign that area of the river levee and so less sediment collects. More work needs to be done before the levee is certified by the corps’ safety program, Dettle said.

Because the Highway 1 bridge has a center support and most other bridges over it do not, big logs and other debris also tend to collect when the river is flowing during storms. Logs aren’t as big of a problem because they can be plucked out relatively easily, Dettle said.

Dettle said it wouldn’t hurt for residents in low areas near Arana Gulch and Branciforte, Carbonera and Moore creeks to prepare for potential floods this winter by gathering sandbags.

There is also potential for other streets in the city to flood if storm drains become clogged with leaves or other debris.

“There is localized flooding when we get intense storms because the street becomes the (water) storage until the system catches up,” said Dettle.

“One thing people can do to help us: If they have a catch basin in front of their house, keep that clean.”

This month, Public Works spokeswoman Janice Bisgaard published several web pages and downloadable brochures about how residents can prepare for big storms, power outages and floods. It includes information from what to put in an emergency kit to preparing a communication plan with family and friends.

City leaders also plan to have an emergency preparedness fair for residents on Nov. 21 at the Santa Cruz Civic Auditorium. It will include explanations of flood maps, a sandbag demonstration and information from the American Red Cross.

For more detailed flood maps, visit https://msc.fema.gov/portal/ and www.r9map.org/Docs/Santa-Cruz_Risk-MAP-Newsletter_Data-Acquisition_FINAL.pdf

Emergency preparedness fair

What: City leaders will lead an emergency preparedness fair to help residents get ready for severe winter storms predicted with El Nino. The event will include explanations of flood maps, a sandbag demonstration, information from the American Red Cross and information about how to prepare homes for rain and potential flooding.

When: Noon to 4 p.m., Nov. 21.

Where: Santa Cruz Civic Auditorium, 307 Church St.

Cost: Free.

Source: City of Santa Cruz