Regulatory Threshold Source

The source field on a RegulatoryThreshold provides the legal and regulatory provenance for the limit — for example, "40 CFR Part 264 Appendix IX" or "NPDES Permit No. CA0012345, Table B." This citation appears in exceedance reports and is essential when reporting a threshold exceedance to a regulator or responding to an agency inquiry. It also helps staff confirm that the thresholdValue entered in Piper reflects the current, authoritative limit from the cited document rather than an outdated or incorrectly transcribed figure.