In the last week, three dogs died from heat-related illnesses while visiting the recreation area in Fredericksburg, just west of Austin.
The park last month tweeted that the area is 133 degrees. It urged followers to "pace yourself in the Texas heat."
Two of the dogs died on the same day and a third perished a different day.
It is unclear if the pets had the same owners, or if there is a possibility of animal cruelty charges.