ITC manages several large private surface water systems from mountain stream intakes through extensive ditch and tunnel systems, surface reservoirs, pipelines, filters, and pump stations to end-user. Our 40-plus years of experience with numerous statewide agricultural irrigation systems provide a solid foundation for efficiently and cost-effectively keeping these systems productive as they continue to age. Flume replacements with economical HDPE inverted siphons and slip lining of fragile tunnel systems with HDPE piping have extended the service life of several surface water systems at considerably less cost than would be possible with conventional repairs or replacements.