Query the Water Quality Portal (WQP) for chemical/physical water quality sample results at specified sites
domain: waterqualitydata.us · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Build a GET request to https://www.waterqualitydata.us/data/Result/search with parameters such as siteid, characteristicName, and startDateLo/startDateHi
Set the desired output format per the Web Services Guide
Send the request and parse returned sample results, including result value, unit, and detection condition
Pair Result queries with a prior Activity search if sampling method/activity type context is required
Handle non-detect and censored values explicitly, since these are flagged rather than reported as raw numeric results
Known gotchas
characteristicName must match WQP's controlled vocabulary exactly (e.g., 'Nitrate' vs 'Nitrate-N') or the query returns zero results
Very broad queries with no site/date filter can time out or be rejected; the service is designed for filtered, not full-database, pulls
Result records mix federal, state, and volunteer-monitoring data of varying QA/QC rigor; check provenance fields before treating results as regulatory-grade
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