Five sets of sluices and two weirs are used to control the canal's depth. Bedford also benefits from the presence of weirs and sluices, creating white water opportunities. Open channel flow meters measure upstream levels in front of flumes or weirs. There are also man-made hydraulic jumps created by devices like weirs or sluice gates. The construction of locks (or weirs and dams) on rivers obstructs the passage of fish. Each spillway contains six fixed-crest weirs that are wide. Water is directly removed by irrigation ditches, weirs, and pumping stations. Most of weirs and groynes are therefore required for watermanagement. There are other footbridges with views of the river and its weirs. It remains the only reservoir damming the river rather than being fed from weirs. Many modifications of encircling nets are used, including traps or fishing weirs. The irrigation was accomplished by the use of "shaduf", canals, channels, dykes, weirs, and reservoirs. The Calusa also made fish traps, weirs, and fish corrals from wood and cord. Along the intervening stretch of the river a series of locks and weirs were built. The stretch is made navigable by the use of locks and weirs.