Water power has never been an important source of industrial power in Texas because of the irregular and frequently insufficient flow of Texas rivers. As early as 1822, however, James Bryan contemplated building a gristmill on the Colorado River, and a few years later Jared E. Groce was granted land over and above his headright for constructing a gristmill and sawmill on the Brazos. About 1825 George Huff and others obtained land from the Mexican government to locate a saw and grist mill on the San Bernard, but the contract was voided in May 1825. A few mills using water power were probably built, although most of the early gristmills, sawmills, and cotton gins were powered either by steam or by oxen. Various types of water wheels could have been used to transmit power directly through shafts and belts to the mill machinery. In 1841 William Kennedy reported that he believed the streams of Texas afforded great facilities for water mills, but by 1882 there were few mills in the state over twenty-five years old and little utilization of water power except in localities where there were swift moving streams with natural falls, such as a woolen manufacturing plant on the Comal River. Many of the mills had to maintain an auxiliary steam plant. A natural dam and series of three falls at Marble Falls resulted in the establishment of a number of flour mills, cotton gins, gristmills, and a cottonseed oil mill. By 1890 a new type of turbine wheel had begun to replace older styles of water wheels, and some electric power was being generated by hydroelectric plants. Numerous small power plants, such as one on the San Marcos River near Prairie Lea, were operated by private owners. The Prairie Lea mill had a dam constructed of a timber framework filled in with rocks; its turbine wheel could produce forty-five horsepower under a seven-foot head. The power operated a gin, a corn mill, and a Wiley dynamo. By 1923 water power in Texas was developing a total of 12,000 horsepower, utilized for ginning cotton, grinding corn, sawing lumber, and generating some electricity. Since the early 1930s the use of water power for direct-connecting machinery has declined, but numbers of hydroelectric plants have been built both as private corporations and as federal projects. On November 1, 1946, of the 194 electric power plants in Texas, twenty-six were hydroelectric generating about 15 percent of the state's electric power. In January 1967 there were twenty-three hydroelectric plants with a total generating capacity of 389,860 kilowatts. In the 1970s major power plant sites included International Falcon Reservoir, six sites on the Highland Lakes of the Colorado River, Amistad Reservoir on the Rio Grande, two sites along the Brazos River, six plants on the Guadalupe River, Denison Dam on the Red River, and Toledo Bend Reservoir on the Sabine River. In the later part of the twentieth century the use of hydroelectric power continued to decline as compared to other means of power generation. In 1992, of the 390 generating units in Texas and thirty units outside Texas supplying power to the state, only 1 percent were hydroelectric. In 1994 there were twenty-three hydroelectric power plants in Texas, or, more specifically, twenty-three dams with power facilities. The facilities contained a total of forty-four generating units with a total generating capacity of 541.7 megawatts.