40 CFR 122.48: Requirements for recording and reporting of monitoring results (applicable to State programs, see § 123.25).

All permits shall specify:

(a) Requirements concerning the proper use, maintenance, and installation, when appropriate, of monitoring equipment or methods (including biological monitoring methods when appropriate);

(b) Required monitoring including type, intervals, and frequency sufficient to yield data which are representative of the monitored activity including, when appropriate, continuous monitoring;

(c) Applicable reporting requirements based upon the impact of the regulated activity and as specified in 40 CFR part 3 (Cross-Media Electronic Reporting Regulation), § 122.44, and 40 CFR part 127 (NPDES Electronic Reporting). Reporting shall be no less frequent than specified in § 122.44. EPA will maintain the start dates for the electronic reporting of monitoring results for each state on its Web site.