The jail holds both local and federal suspects awaiting trial. Around 30 of the hundreds of Capitol riot suspects who were arrested in the wake of Jan. 6 are being held at the D.C. facility.
The Marshals surprise inspection at the facility came shortly after a Federal judge held the warden and corrections director in contempt of court over a Florida suspect who broke his hand in May and went months without surgery.
Although the facility housing the Jan. 6 suspects was found to be a sufficient, a second facility was found to fall short of minimum standards.
About 400 inmates from the second facility will be moved to another detention center in Pennsylvania.
Attorney General Merrick Garland had said during congressional testimony last month that the Marshals were conducting the inspection and the Justice Department was "conducting a review" of the conditions at the jail.