What changed in the registers

Every California air district that publishes an ERC register publishes it as a snapshot — a spreadsheet, a PDF, a database page — and replaces it with the next one. Nobody keeps the differences. The Exchange does: each time a district's register is re-read, it is compared with the previous edition certificate by certificate, and what changed is recorded here — new certificates, certificates that changed hands, volumes used or adjusted, and certificates that left the register. A change of holder between editions is a transfer the district has recorded; the price is not published unless the district reports it.

Subscribe with any feed reader: /changes/feed.xml. Certificates that leave a register keep their page, marked as no longer listed.

Antelope Valley AQMD · 2026-10-03

First mirrored certificate by certificate: 12 certificates across 4 holders. ERC Registry, updated 5/20/2025. District guide.

Bay Area AQMD · 2026-10-03

First mirrored certificate by certificate: 425 certificates across 161 holders. ERC Bank Status database (baaqmd.gov), retrieved 2026-10-03. District guide.

Butte County AQMD · 2026-10-03

First mirrored certificate by certificate: 30 certificates across 11 holders. District ERC Registry, August 2025. District guide.

Eastern Kern APCD · 2026-10-03

First mirrored certificate by certificate: 52 certificates across 14 holders. Banking Certificate Registry, reviewed Aug 25, 2026. District guide.

Imperial County APCD · 2026-10-03

First mirrored certificate by certificate: 328 certificates across 37 holders. Certificates Bank, Aug 25, 2026 (records-request response). District guide.

Monterey Bay ARD · 2026-10-03

First mirrored certificate by certificate: 16 certificates across 16 holders. Active ERC Registry (Summary of Emission Banking Transactions) as of September 5, 2025; Community Bank ERCs as of September 5, 2025. District guide.

Mojave Desert AQMD · 2026-10-03

First mirrored certificate by certificate: 39 certificates across 25 holders. District-Wide ERC Summary dated September 15, 2026. District guide.

North Coast Unified AQMD · 2026-10-03

First mirrored certificate by certificate: 4 certificates across 4 holders. ERC Banking Register, Active Registry (last revised Jan 5, 2016; printed Nov 22, 2022). District guide.

Santa Barbara County APCD · 2026-10-03

First mirrored certificate by certificate: 100 certificates across 24 holders. Active ERC certificates, run date Sept. 22, 2026. District guide.

San Diego County APCD · 2026-10-03

First mirrored certificate by certificate: 185 certificates across 48 holders. ERC Banking Registry, Class A active ERCs, last update August 12, 2025; MERC Banking Registry, last update May 18, 2023. District guide.

San Joaquin Valley APCD · 2026-10-03

First mirrored certificate by certificate: 2,305 certificates across 411 holders. Available Emission Reduction Credits, district reports of 2026-10-03. District guide.

Tehama County APCD · 2026-10-03

First mirrored certificate by certificate: 24 certificates across 14 holders. District ERC Bank log, Nov 24, 2025 (records-request response). District guide.

Ventura County APCD · 2026-10-03

First mirrored certificate by certificate: 166 certificates across 58 holders. ERC Certificates by Company report dated Monday, July 20, 2026. District guide.

Yolo-Solano AQMD · 2026-10-03

First mirrored certificate by certificate: 137 certificates across 49 holders. District ERC Registry, May 19, 2025. District guide.

Feather River AQMD · 2026-10-02

First mirrored certificate by certificate: 133 certificates across 72 holders. District ERC Register workbook (fraqmd.org), active certificates. District guide.

South Coast AQMD · 2026-10-02

First mirrored certificate by certificate: 760 certificates across 358 holders. ERC & STERC Active List, July 2026. District guide.

Sacramento Metro AQMD · 2026-10-02

First mirrored certificate by certificate: 203 certificates across 32 holders. Current ERC Certificate Holders report dated 18-Sep-26. District guide.