Lava Field. Historically, it sustained a quarry, prompting the creation of the Kelly Butte Jail, which used prisoner labor (under guard supervision) to gather crushed rocks for building roads in Portland until the 1950s. In general, rocks from the Boring Lava Field have been used for masonry projects including retaining walls, garden walls, and rock gardens, especially oxidized and scoriaceous rocks. Despite the prevalence of quarrying activity in historical times, there is no ongoing mineral or aggregate resource mining near the Boring Lava Field. In 1952, after a local vote, the Kelly Butte Civil Defense Center was built between 1955 and 1956, costing about $670,000. The center was constructed to host local government agents should a nuclear attack on Portland occur; it had an area of , intended to host 250 people in case an emergency government became necessary. It was known throughout the United States as a model facility for local governments, and in 1957, the docudrama A Day Called X included footage of the Defense Center. The center was left obsolete after a 1963 Portland City Council vote to abolish it passed; in 1968, just one permanent employee remained. Eventually the building was converted into an emergency services dispatch center from 1974 through 1994, when it was abandoned due to rising costs for renovation and space limitations. That same year the building was vacated, and then it was sealed off in 2006. A sixty-bed isolation hospital operated at Kelly Butte from September 1920 until 1960, supporting patients with communicable disease. A water tank stood in the area from 1968 through 2010, when it was replaced with a underground reservoir that cost $100 million, despite opposition from local environmental groups like the Friends of the Reservoirs. Historically, the park has also housed a police firing range, and Kelly Butte remains a recreational space today, administered jointly by Portland Parks and Recreation and the Portland Water Board. In 1981, the Portland city government built a reservoir at the north end of Powell Butte (part of the Boring Lava Field), which still serves the city. In 1987, Portland government created Powell Butte Nature Park, covering of meadows and forest within the city. Planning started in 1995 for a second water reservoir in the area, which was built between 2011 and 2014. The new reservoir is underground, buried under topsoil and native plants, and it has a volume of . With the