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Design and Installation of ITRC Flap Gates


 Date: Ongoing
 Location: Throughout California
 Sponsors: U.S. Bureau of Reclamation, Mid-Pacific Region
 Reports Available:   ITRC Report No. R 07-001


The ITRC Flap Gate is a simple, inexpensive hydraulic gate for automatic upstream water level control.  It operates steadily at varying flow conditions and maintains the water level elevation typically within ±0.5 inches of design. The only moving parts are two bearings, plus stabilizers. ITRC usually designs and constructs the first ITRC Flap Gate that is used in an irrigation district. Subsequent gates are usually built in-house by the districts because of the simple flat plate construction – often based on ITRC design assistance. The gates are often installed in less than two hours while water is flowing. The ITRC Flap Gate requires no electricity and has been installed at over 300 locations in California. They are ideal for small flows in the 15-50 CFS range, where there is a drop of at least 2.5’ across the structure.


ITRC began to investigate early designs of Flap Gates in 1992. The gates originated in The Netherlands in the 1940s, but no design criteria were available. ITRC developed an Excel design program that uses a combination of theory and coefficients from field results – and has continued to improve the program almost every year. District staff at Turlock ID and Chowchilla WD provided valuable feedback with early models. This report includes information on design, installation, maintenance, water conservation and efficiency, cost, use, and benefits.

For updated design details, go to our Flap Gate page.


ITRC Flap Gate at San Luis Canal Company in central California