Creating a Roadmap to Standardize Golden State Water’s SCADA Modernization

GSW provides water service to more than 1 million customers across more than 80 communities in Northern, Coastal, and Southern California. As part of a comprehensive infrastructure review, GSW selected the Simi Valley, Los Osos, and Orcutt districts as models for future SCADA upgrades. The project required standardized designs that could modernize district infrastructure, align with GSW operations management interface (OMI) standards, and support broader expansion across its service areas.

Tetra Tech conducted site evaluations and field assessments to identify required upgrades, then designed SCADA system improvements for the three districts. Our team developed designs to replace near end-of-life Momentum programmable logic controllers (PLC) with Modicon M340 PLCs, integrate Red Lion Graphite human machine interfaces (HMI) and operator interface terminals (OIT), add alarm functions, and implement new reporting infrastructure through AVEVA System Platform OMI.

Our engineers also developed electrical construction documentation, including conduit and tower details, piping and instrumentation diagrams (P&ID), and PLC designs. The team planned new instruments where needed so sites could use standardized input/output (I/O) profiles and control strategies during construction and operation. Working closely with GSW’s SCADA team, we delivered a streamlined bid package for the execution phase. The resulting designs created a practical roadmap for unified modernization, with a long-term goal of extending standardized SCADA upgrades across 30 districts.