Contra Costa County Buchanan Field

Overview and location

Permits and applications Evidence: SMARTS record

Receiving water

Reported by the facility Evidence: facility-reported

Walnut Creek

Discharges directly / indirectly

N / N (as answered in the permit application)

2026 Integrated Report status Evidence: State-published

Walnut Creek is on the 2026 Clean Water Act section 303(d) list (5 Appendix A decisions; category 5).

Published by the State Water Resources Control Board (2026 California Integrated Report, Appendix A). Listing status is taken from Appendix A only. State Board adoption 2026-02-03; USEPA approval not confirmed. A listing describes the waterbody, not this facility. Waterbody profile.

Reported monitoring results Evidence: facility-reported

Numeric Action Level (NAL) screening is being independently validated and is not shown. Nothing on this page states whether a result exceeded a NAL.

163 distinct measurements across 3 parameters, most recent sample Nov 13, 2025.

By reporting year

By parameter

All results (163 distinct rows)

Results are shown exactly as reported by the discharger. Identical rows repeated in the State's export are shown once. Where the export contains different versions of the same sample and parameter, each version is listed and flagged. Details.

Compliance and enforcement records Evidence: SMARTS record

These are records as the State Water Board publishes them in SMARTS, with the source's own types and statuses. They are not a compliance determination or rating. A record listed here is not proof of a violation beyond what the source states, and the absence of records does not establish compliance.

Each record type is counted by its own SMARTS identifier. A violation and the enforcement action that cites it are two records in two lists; they are never added together.

Sources and provenance

Relationships computed 2026-10-22 with methods facility_huc12/1, proximity/1, receiving_water/2, tmdl_reference/1, waterbody_huc12_ovl/1, waterbody_huc12_pub/1; proximity threshold 1.0 km.

How to read the evidence labels

• Evidence: SMARTS record Evidence: facility-reported Information as published in SMARTS or reported by the discharger.
• Evidence: identification corroborated The reported receiving-water name identifies one official waterbody and the facility's location is consistent with it. It does not establish a discharge pathway.
• Evidence: candidate, awaiting review Evidence: not confirmed The reported name could match one or more official waterbodies, but no identification has been confirmed; nothing is assigned without review.
• Evidence: spatial Evidence: geographic proximity Derived from the reported location only.
• Evidence: SMARTS-reported Source records whose links to official references are not yet reviewed.
• Evidence: unavailable The information could not be loaded or is not in the sources.

Records are shown as published and are not compliance determinations. How geographic context is derived.