Water levels are so low at Canyon Lake in Texas that an underwater cave and remnants of communities that stood more than a century ago at the site are reappearing.

The lake, located in Comal County just northeast of San Antonio, is a man-made lake spanning 8,200 acres with 80 miles of shoreline. It was constructed in 1958 to help mitigate flooding and preserve water and was filled with water by 1968, according to the US Army Corps of Engineers.

The area has experienced little rain over the summer. The drought combined with high heat to produce all-time low water levels. On Wednesday, the level fell to 890.89 feet, according to the US Army Corps of Engineers, which the agency said is about 18 feet lower than normal and the lowest recorded level in recent history.

JM Perez captured images on Tuesday showing the cave, which is usually underwater. He said the rare sighting was bittersweet.

"I work on the lake, so I've been watching it drop," he told CNN. "We are a little over 18 feet low now. It is very sad to see it but on the other hand, it is very cool seeing some of the hidden caves. As well the history that is coming to the surface."

The towns of Hancock and Crane's Mill, founded by German immigrants in the 1850s, once occupied the space now filled by water, according to CNN affiliate KSAT. Some of Perez' images show remnants of a house that laid on the lake's flood as well as the Hancock bridge.

The water levels seemed to drop precipitously -- in images captured by Porsche Devol on September 2, only a small portion of a cave was visible and now photos show a vast entrance with rock formations and stalactites hanging from the ceiling.

"I haven't seen the water this low since I moved here," Devol told CNN. "It's actually kind of sad."

The US Army Corps of Engineers told CNN they regularly monitor water levels at the lake and they close lakeside recreation facilities for safety reasons when the water is too low. In addition to the cave and remnants of the former communities, trash and other items have also appeared as the lake's surface has dropped, according to the agency.

"It is common to find dumped items whenever the lake level drops," Clay Church, a spokesperson for the US Army Corps of Engineers' Fort Worth District, told CNN. "Old tires seem to be the most common items that we find."

The US Army Corps of Engineers also urged people to use caution when visiting the lake. "As the lake level drops, there are more underwater hazards such as tree stumps and large rocks that are at or near the surface," Church said. "These hazards present greater risks to boaters and swimmers."