In conjunction with the Florida Department of Environmental Protection (FDEP), the St. Johns River Water Management District (SJRWMD) is beginning rulemaking to update the environmental resource permitting (ERP) stormwater design and operation regulations, using the most recent scientific information available, as required by paragraph 373.4131(6)(a), F.S. (2020). The coordinated rulemaking pursuant to this notice is expected to include amendments by FDEP to update chapter 62-330, F.A.C., and ERP Applicant’s Handbook Volume I (which applies statewide), plus SJRWMD’s amendments to its ERP Applicant’s Handbook Volume II (which applies within the SJRWMD region). Therefore, part of the purpose of this rule development is to revise SJRWMD’s rules consistent with DEP’s amendments to chapter 62-330 and ERP Applicant’s Handbook Volume I. The purpose and effect of the proposed amendments will be to: (1) update stormwater design and operation regulations incorporated by rule in the document entitled “Environmental Resource Permit Applicant’s Handbook, Volume II: For Use Within the Geographic Limits of the St. Johns River Water Management District,” as required by paragraph 373.4131(6)(a), F.S. (2020); (2) update and clarify criteria for basin side slopes and fencing; (3) update and reduce regulatory costs of the Lake Apopka rules; (4) amend stormwater design criteria to promote conservation of groundwater; and (5) otherwise update, simplify, or clarify rules and reduce regulatory costs.