As part of the RHNA process, local jurisdictions have the opportunity to form a subregion to conduct an allocation process that parallels, but is separate from, the regional process [CA Government Code §65584.03]. For the 2015–2023 RHNA, three subregions were formed by the respective jurisdictions in Napa, San Mateo, and Solano counties. The first step in the subregions' RHNA process was for ABAG to determine each subregion's share of the total regional housing need determination from HCD. Housing Element law states that the subregion's share "shall be in a proportion consistent with the distribution of households assumed for the comparable time period of the applicable regional transportation plan" [California Government Code §65584.03(c)]. The household distribution is based upon the county's distribution in 2022 from the Jobs-Housing Connection Strategy of the SCS. Napa received 0.8 percent, San Mateo received 8.7 percent, and Solano received 3.7 percent of the region's total housing need.
ABAG used the income allocation methodology that is part of the region's allocation methodology to determine each subregion's allocation by income. Applying the 175 percent shift in determining the subregion's income distribution helps to overcome the existing income disparities among counties (and the jurisdictions in those counties) and move jurisdictions closer to the regional distribution. If a subregion's income allocation were based solely on its existing income distribution-without applying the 175 percent shift-the region would be unable to effectively share responsibility with the subregions for providing affordable housing and avoiding over-concentration of these units.
Once it received its share of the region's total housing need by income, each subregion was then required to meet the same statutory requirements as the regional allocation process, and was responsible for completing each step in the allocation process. This included developing its own methodology, issuing draft allocations to member jurisdictions, conducting the revision and appeal processes, and issuing final allocations. Each subregion was also required to ensure that its final housing allocation is consistent with the Bay Area's Sustainable Communities Strategy.
The final allocations for each of the three subregions are below: