This story was updated at 1:55 p.m. EDT. The author of the opinion, GAO General Counsel Thomas Armstrong, does not say whether the $43,000 booth was the best way to provide a secure phone line for Pruitt.
The agency violated the law by using more than $5,000 of fiscal 2017 appropriated funds for an unintended goal without giving lawmakers advance notice, GAO investigators wrote in a report released Monday. The GAO does not have enforcement power, which means Congress or another federal agency must take action if there are to be any legal consequences for the EPA's violations. The lawmakers requested documents from Pruitt that would confirm these allegations. The total price of around $43,000 included renovations to prepare space for the booth, including removing a closed circuit camera system.
GAO declined to comment on whether the soundproof booth, which was built out of a former storage closet in the administrator's office, was the most effective way to ensure private communications.
The agency also said that under its guidelines, a classified phone can not be put on an office desk or in a conference room.
EPA officials said the booth was needed so Pruitt could "make and receive calls to discuss sensitive information ..." The EPA headquarters building already had a SCIF, according to former employees.
GAO stressed it was not ruling on whether Pruitt's phone booth itself broke the law, rather that EPA's failure to notify Congress about its spending above the $5,000 limit was the breach.
-Michael Brune, Sierra ClubFederal law prohibits goverment agencies from dishing out more than $5,000 to "furnish, redecorate, purchase furniture for, or make improvements for the office of a presidential appointee during the period of appointment without prior notification to the appropriations committees of Congress".More news: Fulham's late slip against Brentford sends Wolverhampton up to Premier League
EPA chief Scott Pruitt's ethics problems keep piling up.
"An illegal privacy booth to conduct secret discussions with his polluter friends does nothing to help our health or environment", Udall said.
Pruitt is one of President Donald Trump's most controversial appointments and has done what he said he would when Trump named him to oversee the country's environmental regulations - dismantle numerous restrictive policies on the environmental practices of businesses imposed by the administration of former President Barack Obama. "He must fire him immediately".
Republicans also expressed concerns in response to the GAO ruling released today.
Because the EPA did not report its spending on the booth to Congress, GAO also found that the EPA violated the Antideficiency Act, which forbids an agency from spending beyond legally available amounts.