The water in Medina Lake has fallen so low that the San Antonio Water System is no longer drawing water from it. The shift will affect the water source for the southern portion of Bexar County.
At the end of last week, SAWS shut off its pump in Medina Lake, which is now only five percent full.
"The water remaining is developing some water quality issues," said SAWS Spokeswoman Ann Hayden.
The decision to stop pumping was due to a concern about the water quality level and the amount of algae.
"We could see the level of these organic constituents increasing and we finally decided it was reaching a level that we could not accept for our potable water purposes," Hayden said.
The rapidly-falling lake is a sign of the severity of the Texas drought. The body of water where people once enjoyed recreational activities is now a puddle compared to what it was three years ago.
But the lake wasn't created for that purpose, it was instead a reservoir that was created to provide additional water in a time of drought.
Previously, the now defunct Bexar Metropolitan Water District pumped one-third of its water from Medina Lake.
"If this had happened during last year or the year before when BexarMet was still in existence there might have been some very challenging days because they wouldn’t have had a ready source of water to provide to this area," Hayden said.
Customers in the area were receiving a mix of Medina Lake and Edwards water but will now receive water entirely from the Edwards Aquifer.