We have something here that is exclusive to Cameron county in south Texas called resacas. They were made in 1918-1928 to bring fresh water for irrigation to the farmers. Ours is privately owned by Bayview Irrigation district and is not used for drinking water. The ones in Brownsville and San Benito are owned by the city and are used for drinking water(before using it they send it thru a water treatment plant). Los Fresnos has resacas too but I don't think they use them for drinking water.
When hurricanes and storms would hit in this area, the Rio Grande would flood and sometimes change course for a while, then when the waters went back down, it left dry riverbeds. The farmers decided to clean these out, connect them and fill them with fresh water. They used mule teams and steam shovels and hand labor to dig them. That's how the resacas came about. Resaca means "reborn" in Spanish.
Here is the one that borders my property. This is taken from the roadway and if you look in the front center, you can see the lock for a gate that shuts off the water. There are locks all along the resaca so flow can be controlled.