flood gates, a row of heavy planks, interlocked with tongue and groove, would be driven across the canal (similar to a cofferdam) above and below the break, and would swell when wet. After the water drained out through the break, it would be repaired. If the break was in the bank or berm of the canal, the crew would drive two rows of stakes, about a foot apart, across the breach, then weaving rope between them. Straw was put in it, and that would slow or stop the water flow. A row of planks were then driven to stop the flow, and then the break would be filled with dirt and rocks. Burrowing animals, such as muskrats, would cause leaks by digging holes. Indiana canals had leaks from burrowing crawfish. Canal companies would often post bounties for muskrats, e.g. the Middlesex Canal. Types of pound Pounds can be described in various ways according to their situation; Summit pound A summit pound is formed at a summit on the canal, and where all the defining locks descend from the pound. Summit pounds are particularly important in canal design, as every boat entering or leaving the pound causes a loss of water. Summit pounds therefore need an independent form of water supply, which may take the form of weirs on adjacent rivers, reservoirs or pumping stations. Common practice during canal design was to make summit pounds as large as practically possible, in order that losing a lockful of water would not lower the water level too significantly. The Rochdale Canal is a good example of a canal with a relatively short summit pound, which requires restrictions on lock workings at certain times. The canal, which is one of three which cross the Pennines, is long, but the summit pound is just . To the north and east, 36 locks descend to Sowerby Bridge, while to the south and west, another 56 locks descend to Castlefield Junction, on the edge of Manchester. The summit pound is above sea level, and is one of the highest summit pounds in Britain. In order to keep it in water, the company built a total of eight reservoirs near the summit pound. Hollingworth Reservoir was at a lower level than the summit, and so a steam engine was installed to pump the water up to a feeder, which delivered it to the summit pound. One reason for