The San Antonio River has a new, modern flood control system in downtown San Antonio. The new system will be much more convenient for all city personnel involved with the operation and maintenance of the flood control gates.
Gates #3, #4 and #5 were installed in 1929 as part of the River Loop bypass channel construction. Gate #3 is just north of Commerce Street and is on the northern intersection of the River Loop and the main channel. Gate #4 is just north of Villita Street and is on the southern intersection of the River Loop and the main channel. Gates #3 and #4 had previously worked in concert to isolate the River Loop from the main channel’s flood water. Gate #5 is just south of Nueva Street on the main river channel. Gate #5 is the gate that controls the water’s elevation in the river’s main channel and the River Loop during normal operation.
With the replacement of Gate #5, the fire department will no longer be required to monitor and regulate the gate during inclement weather. Gate #5 now automatically maintains a constant water elevation upstream, eliminating the need to totally drain the main river channel during a moderate rainfall event.
While Gate #4 is not a constant level gate, it has been changed from a manually-operated gate to a semi-automatic operation. This means that if the sensor in the main flood channel indicates a water elevation that is too high for the river loop, Gate #4 will close completely, protecting the River Loop from flooding while the high water problem in the main river channel is being resolved. Conversely if the sensor in the main channel indicates a water elevation too low for the River Loop area, Gate #4 will raise to the weir setting. This will allow the River Loop to continue operating at the normal water elevation while pouring water into the main river channel. However, Gate #4 will not automatically lower after it has been engaged at either of these settings. It can only be lowered after a visual inspection to ensure that the situation causing the operation has passed.
With new Gates #4 and #5, the use of Gate #3 should be greatly decreased. Gate #3 will only be closed should Gate #5 malfunction and not maintain a constant water elevation in the main river channel.