For nearly four years before federal and state environmental watchdogs descended on Camp Pendleton during a late June inspection, contractors had warned military leaders about apparently persistent problems with the base’s water system, according to newly released documents. Obtained under the federal Freedom of Information Act, the records were generated between 2014 and mid-2017 by contractors hired to clean and inspect Camp Pendleton’s 34 water reservoirs. They buttress an Environmental Protection Agency summer survey of a much smaller portion of the sprawling base’s water system.