(b) The state board shall ensure that regulations for California Phase 3 Reformulated Gasoline (CaRFG3) adopted pursuant to Executive Order D-5-99 meet all of the following conditions:

1. (1) Maintain or improve upon emissions and air quality benefits achieved by California Phase 2 Reformulated Gasoline in California as of January 1, 1999, including emission reductions for all pollutants, including precursors, identified in the State Implementation Plan for ozone, and emission reductions in potency-weighted air toxics compounds.
2. (2) Provide additional flexibility to reduce or remove oxygen from motor vehicle fuel in compliance with the regulations adopted pursuant to subdivision (a).
3. (3) Are subject to a multimedia evaluation pursuant to Section 43830.8.

(c) On or before April 1, 2000, the State Water Resources Control Board, in consultation with the Department of Water Resources and the State Department of Health Services, shall identify areas of the state that are most vulnerable to groundwater contamination by MTBE or other ether-based oxygenates. The State Water Resources Control Board shall direct resources to those areas for protection and cleanup on a prioritized basis. Loans for upgrading, replacing, or removing tanks shall be made available pursuant to Chapter 8.5 (commencing with Section 15399.10) of Part 6.7 of Division 3 of Title 2 of the Government Code. In identifying areas vulnerable to groundwater contamination, the State Water Resources Control Board shall consider criteria including, but not limited to, any one, or any combination of, the following:

1. (1) Hydrogeology.
2. (2) Soil composition.
3. (3) Density of underground storage tanks in relation to drinking water wells.
4. (4) Degree of dependence on groundwater for drinking water supplies.