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Network NPDES inventories (EPA ECHO)

Verified inventories of CWA-permitted facilities per watershed basin, pulled from EPA’s ECHO Clean Water Act REST services (cwa_rest_services). Every facility, NPDES ID, and value here was returned by the ECHO API — nothing is fabricated, inferred, or filled in. Three basins are committed today, each with its own <basin>-wwtp.* fileset: the Maumee (watermark npdes, the default), the Great Miami (watermark npdes --basin great-miami, the Miami-basin sites — Urbana, Springfield, WPAFB, Troy-Piqua, Hamilton-Middletown), and the Little Miami (watermark npdes --basin little-miami, the Scenic-River sites Xenia and Wilmington / Todd Fork, a single HUC-8 05090202). One further basin is registered in the connector but not yet committed: the Scioto (--basin scioto, the Columbus / New Albany data-center cluster) — deferred on an ECHO 300/hr throttle (HTTP 429). Run watermark npdes --basin scioto to write its <basin>-wwtp.* fileset when ECHO is healthy. Add a basin by registering it in watermark.hydrology.connectors.echo; never hardcode one into the connector.

What the watershed is

Seven USGS HUC-8 subbasins (subregion 0410, Western Lake Erie), queried one at a time via p_huc:

Adjacent WLE subbasins 04100001 (Ottawa-Stony), 04100002 (Raisin), and 04100010 (Cedar-Portage) are not Maumee drainage and are excluded.

Files

Structured YAML, each with a meta: provenance block. null is a genuine ECHO null (never an estimate); true/false flags are booleans.

• maumee-wwtp.all-npdes.yaml — meta: + facilities: list of all active CWA-permitted facilities ECHO returns for the seven HUC-8s, deduplicated to one record per facility by FRS Registry ID (POTW + non-POTW + federal + private/package).
• maumee-wwtp.potw.yaml — same shape, restricted to the subset flagged POTW by ECHO’s CWPFacilityTypeIndicator (municipal plants).
• maumee-wwtp.huc-counts.yaml — huc_counts: per-HUC manifest (ECHO’s reported count vs. rows actually pulled — they match, no pagination loss) plus totals: (raw / deduped / potw).

Method

Per HUC-8: get_facilities (p_huc=<HUC8>, p_act=Y) returns a QID + summary count; get_qid pages the rows as JSON, columns selected by name (mapped to ECHO ColumnIDs). Deduplication keys on FRS Registry ID; a facility holding multiple permits keeps its primary NPDES ID with the rest in npdes_ids_secondary. Two distinct FRS IDs sharing a name are never collapsed.

Verified against cwa_rest_services metadata CWA v2017-10-13 1325 (260 result columns). Numbers come from the API’s structured fields, not any text layer.

Headline counts (last pull)

1,057 active-permit rows across the 7 HUC-8s → 1,006 facilities after FRS dedup: 129 POTW, 875 non-POTW, 2 federal. POTW design flow present for 112/129 (the 17 blanks are mostly Michigan general-permit stabilization lagoons that don’t report a design-flow number).

Great Miami River basin (great-miami-wwtp.*, #446/#455)

The Great Miami (subregion 0508, an Ohio River tributary) is two Ohio HUC-8 subbasins — same p_huc method and field shape as the Maumee, but the Lima-specific in_lima_subbasin / ottawa_discharge flags are omitted (a Maumee-only concept):

Whitewater (05080003) is predominantly Indiana drainage and is excluded (mirroring the Maumee’s excluded WLE neighbors). Last pull: 289 active-permit rows across the 2 HUC-8s → 286 facilities after FRS dedup, 81 POTW. The City of Springfield WWTP (OH0027481, 25 MGD, → Mad River) is present, but ECHO carries no receiving-water value for it, so the basin-screen reports it unscreened rather than guess (same gap as Lima WWTP, caveat 5). Files: great-miami-wwtp.all-npdes.yaml, great-miami-wwtp.potw.yaml, great-miami-wwtp.huc-counts.yaml.

Known gaps & caveats (read before using)

1. No CWNS ID. The ECHO CWA facility service has no CWNS column, so the requested CWNS cross-check for POTWs is not available from this API. POTW classification here rests solely on CWPFacilityTypeIndicator. (CWNS IDs would have to come from the Clean Watersheds Needs Survey, separately.)

2. HUC geocoding (WATERS). ECHO links facilities to HUCs via WATERS; not every NPDES ID geocodes, so a pure watershed query can miss facilities whose coordinates didn’t resolve. RadWBDHu8 is frequently null in the raw data — we use FacDerivedHuc (which reliably reflects the queried HUC-8) instead.

3. Cross-state completeness. Four subbasins (St. Joseph, St. Marys, Upper Maumee, Tiffin) extend into Indiana and/or Michigan. ECHO’s p_huc did return IN/MI facilities (e.g. Auburn IN, Amboy Twp MI), but for a complete inventory this pull should still be cross-checked against Ohio EPA, Indiana IDEM, and Michigan EGLE NPDES permit lists; any facility in a state list but absent from ECHO should be flagged. (Not yet performed — those state datasets are a follow-up; this is an ECHO-only inventory.)

4. “All” is the active CWA universe, not just process wastewater. p_act=Y includes some non-NPDES Industrial-User/pretreatment permits and stormwater general permits alongside true wastewater dischargers. The permit_type (CWPPermitTypeDesc) and facility_type fields make the distinction visible — filter on them rather than assuming every record is a wastewater outfall.

5. ottawa_discharge undercounts. This optional flag is keyed on ECHO’s CWPStateWaterBodyName string, which is null for ~70% of the Ohio rows — including Lima WWTP (OH0026069, 18.5 MGD), the largest Lima-area POTW, which discharges to the Ottawa River but has no receiving-water value in ECHO. Per the “no inference” rule we do not backfill it. Use in_lima_subbasin (every Auglaize + Blanchard record) plus county for the broad Lima/Allen screen, and treat ottawa_discharge: true as a floor, not a complete list.

Field reference

Each entry under facilities: carries these keys (null = ECHO returned nothing):

Cataloged datasets — generated from data/catalog/reference/; run watermark catalog render --apply after editing an entry.

echo-great-miami-wwtp — Great Miami-basin NPDES discharger inventory (EPA ECHO)

Source: EPA ECHO — cwa_rest_services (CWA v2017-10-13) · License: U.S. Government work (public domain) · Access: throttled · Site scope: basin:great-miami · Refresh: quarterly (ttl 180d)

Regenerate: watermark npdes --basin great-miami

echo-little-miami-wwtp — Little Miami-basin NPDES discharger inventory (EPA ECHO)

Source: EPA ECHO — cwa_rest_services (CWA v2017-10-13) · License: U.S. Government work (public domain) · Access: throttled · Site scope: basin:little-miami · Refresh: quarterly (ttl 180d)

Regenerate: watermark npdes --basin little-miami

echo-maumee-npdes — Maumee-basin NPDES discharger inventory (EPA ECHO)

Source: EPA ECHO — cwa_rest_services (CWA v2017-10-13) · License: U.S. Government work (public domain) · Access: throttled · Site scope: basin:maumee · Refresh: quarterly (ttl 180d)

Regenerate: watermark npdes --basin maumee