requires reducing the chamber's width, length, or elevating height. Note that the elevating height has already been reduced by staging the total elevation change into three locks. Were this change done in a single lock chamber, the water volume lost would be three times as much. The water-saving basins function as follows: The volume of water moved by the lock chamber (e.g., a height of ) can be divided into five equal horizontal "slices" (here, 1.8 m each). When the canal begins operation, the chamber is filled once from Gatun Lake. Then, when emptying the chamber, the top three slices (1, 2, and 3) are emptied, one by one, into three basins, each at a successively lower elevation. That is, water slice 1 is emptied, using gravity and valves, into a basin that is at the same level as water slice 2. Then water slice 2 is emptied into a basin at the same level as water slice 3, and slice 3 is emptied into a basin at the same level as slice 4. Water slices 4 and 5 are emptied into the next lock chamber and "lost" (as in the original canal locks). When the lock moves a ship upward, the chamber is closed, and the water from the basin at level 4 is let into the chamber, filling slice 5. Then basin level 3 fills level 4, and basin 2 fills level 3. Next, from levels 2 and 1 are filled from Gatun Lake, "costing" a volume of instead of over the chamber area (2/5 of the elevation height). The ship is now at the level of Gatun Lake and can cross it. Navigational channels According to the plan, a -long access channel was excavated to connect the new Atlantic locks with the existing sea entrance of the canal. To connect the new Pacific-side locks with the existing channels, two new access channels were built: The north access channel, which connects the new Pacific-side lock with the Culebra Cut, circumventing Miraflores Lake. This channel runs along the new Borinquen Dam that separates it from Miraflores Lake (which has a water level that is 9 m lower, due to the dislocation of the Pedro Miguel locks). The south access channel, which connects the new lock with the existing sea entrance on the Pacific Ocean (fig. 5). The new channels on both the Atlantic and the Pacific sides are at