Hamilton's Grotto, Austin, Texas
Hamilton Pool Preserve is a historic swimming hole which was designated a preserve by the Travis County Commissioner's Court in 1990. Located 3/4 mile upstream from its confluence with the Pedernales River, Hamilton Creek spills out over limestone outcroppings to create a 50 foot waterfall as it plunges into the head of a steep box canyon. The waterfall never completely dries up, but in dry times it does slow to a trickle. However, the pool's water level stays pretty constant, even during periods of drought.
The preserve is home to the Golden-Cheeked Warbler, and a great variety of other birds. The diverse vegetation of Hamilton Pool ranges from semi-arid species in the uplands to riparian species in the canyon. The uplands of the preserve are a juniper and oak savannah with a variety of native grasses and wildflowers. Several rare plant species including canyon mock-orange, red bay (western-most colony of this eastern species), and chatter box orchid are known to occur in the canyon areas along Hamilton Creek. (Taken from Travis County Website)