Modesto Regional Water Treatment Plant

The Modesto Regional Water Treatment Plant is owned and operated by the MID. Completed in late 1994 and expanded in 2016, the plant provides a quality drinking water supply for Modesto area residents.

It now treats and delivers up to 67,000 acre-feet per year to the City of Modesto, supplementing the City’s groundwater supply. MID's arrangement with the City is detailed in the Amended and Restated Treatment and Delivery Agreement.

The water source is the Tuolumne River, which begins high in the Sierra Nevada Mountains. At Modesto Reservoir, water enters the plant’s state-of-the-art treatment process that ensures the water supply meets or surpasses all state and federal drinking water standards now and in the future.

Tours are not available at this time. For more information on the Modesto Regional Water Treatment Plant, send an email to the MID Public Affairs staff.

Domestic Water Policy Committee

The Domestic Water Policy Committee consists of two Modesto City Council members and two MID Board members.  The Policy Committee oversees the management and operation of the Modesto Regional Water Treatment Plant.  The Policy Committee must meet at least twice each year, however, the Committee can and has met more often when significant projects are in process (typically the first Monday of each month).  Meetings take place in the MID Board Room at 1 p.m., unless otherwise noticed.  Agendas are available here.

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 five 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 2020 Watershed Sanitary Survey.

Watershed Sanitary Survey - Final

• Appendix A - SFPUC WEIP 2015-2016 Annual Report
• Appendix B - NPDES and WDR Permits
• Appendix C - Local Agency Management Programs for Tuolumne and Stanislaus Counties
• Appendix D - Basin Plan Objectives
• Appendix E - DPRA Rules and Regulations
• Appendix F - Modesto Irrigation District Domestic Water Supply Permit
• Appendix F - Modesto Reservoir Management Plan
• Appendix G - Invasive Species Public Education Materials (Part 1)
• Appendix G - Invasive Species Public Education Materials (Part 2)
• Appendix H - Post Rim Fire Monitoring Data Collected by MID
• Appendix I - Summary of Federal and California State Water Quality Regulations
• Appendix J - Excerpts from Stanislaus Regional Water Authority Surface Water Supply Project
• Appendix K - Modesto Regional WTP - Title 22 Constituents
• Appendix L - Proposed Phase 2 Extended Monitoring Program for SRWA
• Appendix M - Photos
• Appendix N - SRWA/MID 2020 Watershed Sanitary Survey - DDW Report Comments and Responses