El Salvador Reservoir Transparency

For the COVERED subset (the 4 Lempa cascade reservoirs — Cerrón Grande, 15 de Septiembre, 5 de Noviembre, Guajoyo — which represent essentially the entire managed hydropower estate of El Salvador), publication is universal and near-daily by the Unidad de Transacciones at estadistico.ut.com.sv/Embalses.aspx, without registration. However, data is expressed only in meters above sea level (msnm), not as storage volume (Mm³) or percentage of capacity, meaning the raw figure requires external stage-storage references to be actionable. CEL's own website publishes no operational data; the Memorias de Labores contain only aggregate annual generation statistics. DGEHM provides a secondary visualisation of the same UT data.

For the COVERED subset, the dominant access mechanism is an interactive HTML dashboard (estadistico.ut.com.sv/Embalses.aspx) with no documented machine-readable download (CSV, JSON, Excel) and no REST API. The MARN/SNET hydrological bulletin pages return HTTP 403 when fetched programmatically. The UT's monthly statistical reports portal (2007–2026) uses a WebDAV-style file system containing PDFs rather than structured data. No open data catalogue entry for reservoir storage exists at datos.gob.sv. The graficostr.ut.com.sv real-time operations page exists but is equally inaccessible for bulk extraction.

Conservative estimate — denominator includes small Lempa tributary dams and ancillary impoundments (small hydroelectric plants on tributaries like Sucio and Atehuat, small irrigation reservoirs in the Lempa basin), private agricultural ponds, and ANDA-managed municipal water-supply reservoirs that supplement the four Lempa cascade dams. Methodology v1.3.0 (capacity-weighted). Covered capacity through UT publication of the 4 Lempa cascade reservoirs is ~3,300 hm³. A realistic national denominator including small tributary impoundments, private agricultural reservoirs and municipal water-supply storage reaches approximately 3,750 hm³. Score = round(100 × 3,300 / 3,750) = 88. The four Lempa cascade reservoirs represent essentially all strategic regulated storage and are reported daily; the conservative discount reflects the long tail of small impoundments not in UT publication.

MEDIAN history for the COVERED subset is approximately 18–19 years. The UT monthly statistical reports span 2007–2026, providing nearly two decades of electricity-sector data that includes reservoir storage context for all 4 covered reservoirs (operational data has been collected continuously since the UT was established in the late 1990s, with the public reporting portal exposing the 2007-onward archive). Journalistic cross-referencing routinely cites UT historical level series back to the early 2010s. The dedicated levels portal does not expose a documented bulk download of the full time series, but the data is consistently dated and retrievable per month back to 2007. MARN/SNET maintains an Archivo Histórico with Lempa River records from 1970 onwards, supplementing the operational series.

For the COVERED subset, the typical cadence is DAILY. The UT reservoir levels dashboard is updated each operating day — media sources consistently cite UT readings with daily precision (e.g. articles dated August 29, 2023 report readings from August 28, 2023). The MARN/SNET publishes a formal Boletín Hidrológico Diario. Neither source publishes sub-daily (hourly or real-time) data, and no automated notification or data feed is available. The UT's real-time operations dashboard (graficostr.ut.com.sv) may display higher-frequency data but could not be confirmed to include reservoir storage.

For the COVERED subset, no public documentation describes how CEL or the UT measure reservoir water levels — sensor types, calibration protocols, datum references, or quality-control procedures are not published on any official website reviewed. The UT reports water level in meters above sea level (msnm) without an explanation of the reference datum or uncertainty range, and without a published stage-storage curve. The SNET/MARN has published a National Plan for Integrated Water Resources Management (PNGIRH) and older technical papers describing the 10-telemetry-station hydrometric network, but these are legacy documents (pre-2010) and do not constitute a current authoritative measurement methodology statement. El Salvador's SDG 6.5.1 IWRM implementation score of 38% (2020–21) reflects this institutional gap.

All primary data sources — UT portal, CEL website, MARN/SNET pages, DGEHM statistics, and the ASA's Sistema de Información Hídrica — are exclusively in Spanish. No English-language interface, translation layer or English metadata is provided for any reservoir dataset. International researchers must navigate entirely Spanish-language systems. The only English-accessible content about El Salvador's reservoirs consists of third-party references (Wikipedia, IRENA reports, journalistic sources) that do not contain real-time or current storage data.