When a state or authorized Tribe submits a water quality standard for the EPA's review, Clean Water Act section 303(c)(3) requires the EPA to approve the submittal within 60 days or disapprove within 90 days of the date of submission. An EPA disapproval may specify that certain changes are necessary to make the state or Tribal standard comply with the Act. If the state or Tribe does not adopt the specified changes within 90 days of receiving the EPA's disapproval, CWA section 303(c)(4) requires the EPA to 'promptly prepare and publish' a proposed federal water quality standard that complies with the Act. Additionally, the EPA may issue an Administrator’s Determination pursuant to CWA section 303(c)(4)(B), informed in some instances by petitions from external parties, that a new or revised water quality standard is necessary in a state or Tribe to meet CWA requirements. Following an Administrator’s Determination, the CWA similarly requires the EPA to ‘promptly prepare and publish’ a proposed federal water quality standard. The EPA's promulgation of state- or Tribe-specific water quality standards to comply with statutory requirements is expected to occur periodically and on an ongoing basis.