In the design of these structures, the PMF is commonly selected as the IDF, and then the IDF is used to determine the required freeboard; these structures’ freeboard allowance must also factor in wind setup. A leading cause of failure in these structures is piping, which refers to internal erosion. When these structures are built in seismically active areas, (10[1])they must be able to withstand earthquake-induced seiches (“saysh’s”). A split (-5[1])spacing pattern (-5[1])is commonly used when building these structures’ grout (10[1])curtains, (-5[1])which (10[1])reduce uplift pressure. (10[1])Accesses are often built in these structures for anadromous (10[1])(“uh-NAD-ruh-mus”) animals. (10[2])Seepage control (10[2])measures in these (-5[1])structures (-5[1])prevent embankment (-5[1])erosion. (10[1]-5[1])Concrete is used to build these structures (10[1]-5[1])when they have an arch or gravity (10[1])design. For 10 points, (10[1])name these structures built to create reservoirs (10[3])for purposes (10[2])like hydroelectric power generation. (10[1])■END■ (10[5])