Visalia presents revised stormwater master plan focusing on recharge and smaller, targeted projects

City engineers told the council on Aug. 4 that the stormwater master plan update shifts the city’s approach from discharging stormwater to regional retention and groundwater recharge and that staff validated only three priority deficiency projects with a planning-level cost of about $1.4 million.

Catherine, an associate engineer, said the updated plan reevaluated historical standards using a contemporaneous 2-year design storm (rather than a larger, infrequent event) and combined geospatial land-cover analysis with growth projections to assess capacity needs. Staff said changes in residential lot imperviousness, trends toward smaller lots and ADUs, and stricter water-quality rules made the retention approach preferable to increasing discharge to waterways the city does not own.

The master plan designs future basins as standalone retention facilities sized for recharge (assumed planning depth of approximately 18 feet of design water depth within a 23-foot total depth including slopes and landscaping). Staff said retrofit or deepening options for some existing park basins (for example, Burke Park) are constrained and that stand-alone excavation north of Burke Park would likely be needed for improved recharge. Staff also described the follow-on Nexus study for developer impact fees and a rate study under Proposition 218 for stormwater service charges.

Council approved circulating the draft stormwater master plan for public comment and asked staff to return with the Nexus study and rate-study timeline; staff said the Nexus/impact-fee work and a public rate process should proceed within about a year.