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40 CFR §141.521 — What updated watershed control requirements must my unfiltered system implement to continue to avoid filtration?

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
Your system must take any additional steps necessary to minimize the potential for contamination by Cryptosporidium oocysts in the source water. Your system's watershed control program must, for Cryptosporidium:
  1. (a)Identify watershed characteristics and activities which may have an adverse effect on source water quality; and
  2. (b)Monitor the occurrence of activities which may have an adverse effect on source water quality.