The Big Dam
Cisco's boomtown leaders didn't build small. North of town they poured a hollow concrete dam a fifth of a mile long, filled a lake behind it, and put what they billed as the world's largest swimming pool at its feet.
A million-dollar dam for a boomtown
Cisco received its permit to dam Sandy Creek in June 1920, in the middle of the oil boom.source By April 1921 a newspaper reported that excavation on the “million-dollar dam” was more than half done, with concrete poured from two great towers.source
The job took more than 4,000 railcar loads of material, including about 2 million pounds of reinforcing steel and 65,000 barrels of cement, according to that same report.source Dallas firm Elrod Engineering designed it.source The dam was completed on September 7, 1923.source
Hollow on purpose
The Big Dam is an Ambursen-type slab-and-buttress dam. Instead of a solid wall of concrete, a relatively thin, sloping slab rests on a row of buttresses, leaving the inside hollow. The design used far less material than a solid dam of the same size.source
In its day the dam was promoted as one of the largest concrete structures of its kind. Exactly what it was the largest of has been retold many ways since, so we'll let the dam speak for itself.source
The pool and the zoo
Below the dam, Cisco built a recreation park its owners billed as home to the world's largest man-made swimming pool.source Visitors came to swim and picnic, and a small zoo kept animals near the foot of the dam.
The pool closed to the public in the 1970s. Today you can still see the frames of the old diving platform and swing set standing over the empty basin.source
Walk the Old Zoo Nature Trail
In 2021 volunteers with the local nonprofit SAFE cleared the overgrown zoo grounds and opened the Old Zoo Nature Trail. The trail starts from a gravel lot near Williamson Dam and leads past the old animal enclosures.source
Fishing and boating
Lake Cisco holds largemouth bass, catfish, crappie and redear sunfish. source A two-lane lighted boat ramp sits on the south side off FM 2807. The city charges a small lake-use fee and requires a permit, so check before you launch.source
Still working after 100 years
The Big Dam isn't a monument. It still supplies Cisco's drinking water.source Soon after the lake filled, a railroad won a court order to lower its level because backwater was damaging the tracks.source In 1955 the city got a permit to dam nearby Battle Creek to make up the difference.source