Flooding Threat To San Leandro From Rising Sea Levels

SAN LEANDRO, CA — San Leandro might get smaller in 100 years, due to rising sea levels that threaten cities along San Francisco Bay — flooding structures, roads, and possibly cutting off access to I-880 in some areas.

In Alameda County, sea level is predicted to rise six inches by 2030, 11 inches by 2050 and 36 inches by 2100, relative to levels in the year 2000, climate analyst Four Twenty Seven wrote in a report on climate adjustments in San Leandro. San Leandro’s 2035 General Plan accounts for a 55-inch sea level rise by 2100.

The predicted rise in sea level doesn’t account for storms, which temporarily raise the water level further. If combined with a 50-year storm, which has a two percent chance of occurring in any given year, water levels could reach 48 inches by 2050, the report said.

The southwest area in San Leandro is most at risk from sea level rise, according to the report. Though the city’s downtown area and BART station are outside the projected affected areas, the rising sea level could affect residents west of I-880 and cut off parts of the freeway, impeding access to the city.

When rising sea levels are combined with surges, the water level is likely to reach 48 inches by 2100, the city report said. With a 48-inch rise in sea level, Alameda County Fire Department Station 11, the San Leandro Water Pollution Control Plant, Dayton Elementary School and three industrial facilities with hazardous materials onsite would be exposed to flooding.

A 48-inch rise would also risk flooding the city’s shoreline parks, the Union Pacific Railroad and multiple power lines, affecting recreation, commerce and the availability of electricity in San Leandro. Water would encroach on the Oyster Bay Regional Shoreline, the Estudillo Channel and the edges of Marina Park, Marina Golf Course and Tony Lema Golf Course. The marshlands would also be permanently inundated with water, reducing the city’s defense against storm surges and high tides.

One report, by the California Ocean Protection Council Science Advisory Team Working Group, makes an even more dire projection, that sea level in the Bay Area could rise up to 6.9 feet by 2100, relative to levels in the year 2000.

As sea levels rise, the risk of coastal flooding and erosion increases for all Bay Area properties, and groundwater sources could be contaminated with saltwater. If combined with major storms, higher sea levels can cause flooding that damages local structures and cuts off roads and transportation options.

With even four feet of flooding over the next 40 to 100 years, the Bay Area would either lose or need to relocate nearly 104,000 existing jobs, and 85,000 new or planned jobs would not be created, or would be created outside the region, a 2020 report from Adapting to Rising Tides predicts.

The report also says nearly 13,000 existing housing units will no longer be habitable, insurable or desirable, and that 70,000 new or planned units won’t be built, or will be built outside the Bay Area.

The report also calculated the effect of flooding on the community, finding that more than 28,000 socially vulnerable residents would become more vulnerable by having to deal with daily flooding in their homes and neighborhoods.

Read the full City of San Leandro report on Climate Hazard Assessment & Adaptation Options
View Adapting to Rising Tides Bay Shoreline Flood Explorer
Read Adapting to Rising Tides Bay Area Short Report