Watershed Sanitary Survey

The Safe Drinking Water Act Surface Water Treatment Rule and the State of California Title 22, Code of Regulations, requires all domestic water suppliers treating surface water to conduct a Watershed Sanitary Survey of their watersheds and to update the survey every 5 years. The purpose of the survey is to evaluate the potential contaminant sources within the watershed that may impact drinking water quality. Following is the final 2025 Watershed Sanitary Survey.

2025 Watershed Sanitary Survey – Final (PDF)

• Appendix A (PDF) – NPDES and WDR Permits
• Appendix B (PDF) – Local Agency Management Programs for Tuolumne and Stanislaus Counties
• Appendix C (PDF) – Basin Plan Objectives
• Appendix D (PDF) – DPRA Rules and Regulations
• Appendix E (PDF) – Modesto Irrigation District Domestic Water Supply Permit
• Appendix F (PDF) – Modesto Reservoir Management Plan
• Appendix G (PDF) – SRWA WTP Permit
• Appendix H (PDF) – Invasive Species Public Education Materials
• Appendix I (PDF) – Summary of Federal and California State Water Quality Regulations
• Appendix J (PDF) – SFPUC Sanitary Survey (2019 – 2023)
• Appendix K (PDF) – Modesto Regional WTP – Title 22 Constituents
• Appendix L (PDF) – SRWA WTP – Title 22 Constituents
• Appendix M (PDF) – Site Visit Photos