Know your data sources.

Louisiana SONRIS / DNR (now DCE) oil & gas. No auth. - searchWells (~245K) ⭐ filter by parish, operator, status (LEGEND_DES), product - searchSaltDomes (174) ⭐ LA-specific — caverns, sour gas risk, SPR - searchFields (~11K polygons), searchInjectionWells (~4.5K), getWellByApi, getServiceInfo upstream quirks: native sonris-www server is 404, working data is on AGOL mirrors. Well attributes are 10-char-truncated (WELL_STATU/LEGEND_DES). PARISH_NAM stored UPPERCASE. SONRIS production DB has no public API — wells include sonrisLink for browser-session deep dive.

Louisiana State Land Office state-agency tracts. AGOL Feature Service (owner: NBAM_Org), no auth. - searchStateLands ⭐ — 1,026 state-agency tract polygons (LSU, prisons, parks, DOTD) - getStateLandTract — full record by SITE_CODE - getServiceInfo quirks: USE_ is exclusively "STATE AGENCY LAND" — no mineral interests in this layer (those are on SONRIS / la-sonris). Probed: LEASE_OWN_ S/L/M = State-Owned (839) / Leased by State (150) / Mixed (37). PARISH_COD stored both zero-padded ("01") and unpadded ("1") — handler matches both. SURF_INT mostly FULL_INTEREST; 2 records have data-entry typo.

Louisiana DEQ water-quality datasets. AGOL Feature Services, no auth. - search303dImpairedWaters ⭐ — IR2020 subsegments where a designated use is Not Supported (303(d)) - searchSubsegmentsByUse ⭐ — same layer, any use-rating - searchWatershedBasins (12), searchAmbientMonitoringSites (~761 LEAU active), searchFishAdvisories (62) - getServiceInfo quirks: subsegments + flowlines have NO parish — use BASIN (12 names: ATCHAFALAYA / CALCASIEU / ...) or bbox. Use codes: PCR/SCR/FWP/DWS/ONR/OYS/AGR/LAL. Status: Fully Supported / Not Supported / Insufficient Data / Not a Use / No Data Collected. Fish Advisories' Parishes is free-text ("Calcasieu and Cameron"); LIKE-matched. Air emissions + hazardous waste are NOT published as LDEQ Feature Services.