County supervisors explore strategies to address flooding in Bolsa Knolls.

As the end of the rainy season approaches, a long-awaited study on Little Bear Creek and strategies to reduce flooding in the surrounding Bolsa Knolls neighborhood was presented to the Monterey County Board of Supervisors on March 24.

There are between 60 and 80 residential properties prone to flooding in the area, Balance Hydrologics, a Berkeley-based consulting firm, found. The study’s authors recommend culvert enlargement at Paul Avenue and Rogge Road; sediment removal at culvert crossings; vegetation management; and building basins upstream to retain flow and sediment.

The study includes four recommendations mixing and matching from those strategies at a total cost ranging from $550,000 to $1.2 million.

The fifth alternative would be the most costly, up to $6 million, and aligns with FEMA’s Flood Insurance Study from the 1970s. It calls for channel grading.

“Construction of upstream sediment retention and flow detention basins would be the most cost-effective strategy for providing broader flood protection benefits and protection from large storm events,” a report by a county hydrologist states.

Various approaches would require cooperation with private property owners, “increasing the complexity of both design and implementation,” according to the study.

The board asked the Public Works Department to return in two months with more detailed project costs, potential funding sources and information on possibly creating a special district.

“[If] this place is going to continue to have some flooding, we have got to reduce the frequency and the severity of it,” said County Supervisor Glenn Church, who represents the area.

Other alternatives include creating a special district or joint powers authority to manage the creek, and possible code enforcement actions on property owners who live upstream and aren’t controlling erosion.