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Highlight 8-17 of the HRS Guidance Manual, page 223

Highlight 8-17 : Defining Multiple Watersheds

  • In this example, four sources are located at a single site.

  • Establish PPEs for each source.

  • Determine the in­water segment for each PPE.

  • The hazardous substance migration paths for Sources 1,2, and 3 overlap to establish one watershed.

  • The hazardous substance migration path for Source 4 does not overlap with any others; a second watershed is established.

  • Sources 1, 2, and 3 are assigned to Watershed 2 for scoring purposes and Source 4 is assigned to Watershed 1.

  • If the hazardous substance migration path for Source 2 did not reach Blue River (TDL2), three watersheds would be scored ­ Source 1 with a PPE into Blue River, Sources 2 and 3 with PPEs into Yellow River, and Source 4 with a PPE into Red River.


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