Mexico Reservoir Transparency

For the COVERED subset (210 principal dams), CONAGUA's SINA publishes daily storage volumes through the SINA Presas portal showing current storage in million m³, percentage of total capacity, and daily inflow/outflow. The SIH provides per-station CSV downloads via FTP (ftp://presas:presas@sih.conagua.gob.mx/) with multi-decade historical records. The typical covered reservoir has daily structured publication plus historical bulk download. The largest reservoirs (Álvaro Obregón/Oviachic, Miguel Alemán/Temascal, El Infiernillo, La Angostura, Falcón) are all covered.

For the COVERED subset, Mexico offers multiple programmatic tiers, none a clean documented REST API. The GeoServer WMS/WFS endpoint exposes dam location and status layers as OGC services. The SIH FTP server (with published credentials) provides per-station CSV downloads — bulk data access but not a true API. The SINA portal renders data as HTML tables. Datos Abiertos (datos.gob.mx) publishes some CONAGUA datasets including historical daily dam storage records, but as static bulk downloads. Automated daily ingestion requires FTP scripting or GeoServer WFS queries.

Conservative estimate — denominator includes a substantial tail of small-to-medium irrigation reservoirs (Mexico's irrigation district network includes thousands of small reservoirs across Distritos de Riego and Unidades de Riego operated by user associations not in CONAGUA's SINA daily portal), private agricultural impoundments, and small municipal water-supply reservoirs reported only in the annual Estadísticas del Agua. Methodology v1.3.0 (capacity-weighted). Covered capacity through CONAGUA SINA's daily portal (210 principal dams) is approximately 145,000 hm³. A realistic national denominator including small irrigation reservoirs of user associations and private impoundments reaches approximately 165,000 hm³. Score = round(100 × 145,000 / 165,000) = 88. The 210 principal dams contain virtually all the large hydroelectric, irrigation and water-supply reservoirs; the conservative discount reflects the long tail of small/medium irrigation storage outside the daily SINA feed.

MEDIAN historical depth across the 210 covered dams is approximately 30+ years. The SIH FTP server provides per-station CSV files with daily storage data going back to 1991 for many major dams, and some records extend earlier. The SINA portal provides historical comparisons and Datos Abiertos hosts bulk historical dam datasets. CONAGUA's official weekly dam status reports have been published systematically since the early 2000s. With three decades of daily records for the principal dam network as the dominant pattern, the median clearly exceeds 20 years. Band: median 20+ years (well above).

For the COVERED subset, the typical cadence is DAILY. The SINA Presas portal updates dam storage data daily for all 210 principal dams, with timestamps confirming yesterday-to-today updates. CONAGUA also publishes weekly official dam status reports (PDF). The FTP server updates CSV files at daily or near-daily frequency. Daily updates for 210 dams covering the majority of national storage capacity is strong by Latin American standards, comparable to Chile's DGA HIDROlínea and better than Brazil's ONS (weekly).

For the COVERED subset, capacity figures (total, useful, and dead storage) for each of the 210 principal dams are published alongside current storage in SINA. The GeoServer endpoint includes dam elevation and capacity parameters in its attributes. CONAGUA's Anuario Estadístico del Agua documents the national dam registry methodology. However, there is no single publicly accessible document explaining measurement methodology (gauge-to-volume conversion curves, bathymetric survey dates, sensor calibration). Individual dam technical files (expedientes técnicos) with stage-storage curves are not published online for all dams.

All CONAGUA portals, reports, and data systems are exclusively in Spanish. The SINA portal, the SIH FTP file names, the GeoServer layer names, the Datos Abiertos dataset metadata, and the weekly PDF reports are Spanish-only with no English translation layer. Mexico's water authority does not publish dam bulletins, API documentation, or data dictionaries in English.