Regulations, Reporting, and Records
Core concepts
The Clean Water Act and NPDES permit framework govern discharges. Know permit components: effluent limits (monthly average, weekly average, daily maximum), monitoring frequency, reporting (discharge monitoring reports, DMRs), bypass and upset provisions, and the concept of significant noncompliance (SNC). Know that exceedances must be reported per permit timelines and that falsification is a federal crime.
Other rules: pretreatment program and local limits for industrial users, biosolids regulations (40 CFR Part 503) covering pathogen reduction and vector attraction reduction, and spill prevention (SPCC). Operator certification requirements vary by state; continuing education and renewal matter. Records must be retained per permit (commonly at least 3 years, longer for some documents) and be available for inspection.
Traps
Questions confuse monthly average with daily maximum, or assume a single exceedance is automatically SNC. Another trap: "report only if the public complains" - wrong; permit timelines control. Watch for bypass questions: bypass is allowed only under specified conditions with notification. Also, DMR arithmetic errors count as violations.
Worked example / rule of thumb
Permit limit is 30 mg/L monthly average TSS. Monthly results: 28, 32, 29, 31 mg/L. Average = 30 mg/L - at the limit, not over, but the daily/weekly values may still violate other limits. Rule of thumb: compute averages with the exact permit rounding rules, and document every calculation; a math error on a DMR is a reportable violation even if the water was clean.