On the cliffs surrounding Lake Buchanan in Central Texas, a white ring extends some 13 feet above the shoreline, marking where the water reaches when the lake is full. At nearby Lake Travis, staircases that once led to the water’s edge now end well above it.

These two lakes serve as key water sources for dozens of cities and hundreds of farmers, as well as for several power plants. With Texas gripped by drought, water levels have fallen sharply. Combined, the two lakes now hold 28 percent less water than their long-term average.

“This is scary,” said Janet Caylor, who owns two marinas on Lake Travis, the larger of the two lakes, and has had to move her docks as lake levels drop.

The current drought, drier than any other October-through-May stretch in Texas history, has heightened the stakes in an already contentious long-term planning battle over water from these lakes, which feed the lower Colorado River as it runs southeast to the Gulf of Mexico. It has pitted fast-growing cities like Austin, which depend on the water for drinking and recreation, against rice farmers near the Gulf, who need vast amounts of water for irrigation.