Head is the force generated by falling water, and the farther water falls, the more force it produces. To increase that force, Meriwether dammed the San Marcos River. Beginning in 1894, the Zedlers sold excess power to Luling. Herman and Charles expanded the power plant between 1902 and 1907 and built a new powerhouse in 1914 to meet the city's growing demands. Meriwether used stones to build the first dam and rebuilt it repeatedly after floods washed it away. Fritz Zedler replaced it with a log dam that lasted until 1914, when Herman and Charlie Zedler built the concrete dam that stands today. The penstock channeled water so it fell through the turbine, the trash catcher kept large debris from clogging the flow of water to the turbine, and the gates allowed excess water to flow through. Like air on a propeller, water tumbling across the turbine's vanes spins a vertical shaft, and the remaining task was to capture that spin.