Vietnam Reservoir Transparency

EVN operates a public section titled 'Hydropower Reservoir Water Level' (Vietnamese and English versions) that publishes regular news-style articles reporting water levels (metres), inflow (m³/s) and sometimes outflow for the major Da River cascade (Hoa Binh, Son La, Lai Chau) and northern reservoirs (Thac Ba, Tuyen Quang, Ban Chat). Individual articles confirm timestamped operational data is produced daily and shared internally with MARD's Irrigation Department and NLDC. However, there is no live dashboard or centralised open data table: data exists only inside individual HTML news articles, requiring manual retrieval, and storage volume in Mm³ or percentage-full figures are rarely included. Small and medium hydropower reservoirs (the majority of the 173+ plants) have no public operational data, and MONRE/NAWAPI publish no national reservoir storage dataset.

No REST API, no open data format (CSV, JSON, XML), and no structured download mechanism exists for Vietnam's official reservoir data. EVN's portal is HTML-only; data is embedded inside individual news articles that require manual reading. The national open data portal (data.gov.vn) contains no reservoir operational datasets. The MRC Data Portal (portal.mrcmekong.org) offers some structured data for Mekong tributaries but is itself a foreign intergovernmental body, not Vietnam's national disclosure. The third-party Mekong Dam Monitor (Stimson Center, mekongmonitor.stimson.org) provides satellite-derived weekly estimates with free downloads for a subset of major dams, but this is remote sensing, not government-published operational data. No registration is required to view EVN articles, but machine-readable access is not feasible without scraping.

v1.3.0 capacity-weighted with conservative estimation applied 2026-05-29. Vietnam's total reservoir capacity above 10 hm³ is approximately 50,000 Mm³, distributed across ~200-300 qualifying reservoirs. The Da/Red River cascade dominates: Hoa Binh (9,450 Mm³), Son La (9,260 Mm³), Lai Chau, Ban Chat (2,138 Mm³), Thac Ba (2,940 Mm³), Tuyen Quang (2,260 Mm³). EVN publishes near-daily HTML water-level articles for the strategic Da River cascade plus intermittent Mekong cascade coverage — capacity-weighted covered storage ≈ 20,000 Mm³ on a conservative basis. Coverage = round(100 × 20,000 / 50,000) = 40. The conservative revision downward from 50 reflects that smaller hydropower reservoirs, the long tail of independent power producers, MARD irrigation reservoirs, and most Central Highlands hydropower remain uncovered, and that even for the covered Da River cascade, data is locked inside individual HTML news articles rather than fully tabulated per-reservoir disclosure.

EVN's news-article archive for reservoir water levels dates continuously from at least late 2013, with daily bulletin updates visible in the index (articles from November–December 2013 confirmed). This gives roughly 12 years of accessible historical snapshots, but each data point requires retrieving an individual HTML article; there is no bulk download or time-series file. The peer-reviewed MSEA-Res satellite dataset (Zenodo DOI 10.5281/zenodo.14844580) provides 1985–2023 sub-monthly absolute storage for 186 SE Asian reservoirs including Vietnamese ones, freely downloadable under CC-BY 4.0 — but this is a third-party remote-sensing product, not government-published operational data. Official government historical series in machine-readable form do not exist publicly.

The Stimson Center Mekong Dam Monitor (2024 Progress Report) confirmed that Vietnam's EVN provides near-hourly updates on the status of most of its large hydropower dams, including 15+ in the Mekong Basin, on a public website — a level of operational frequency that ranks ahead of most regional peers. Prior to the Mekong Dam Monitor launch, Vietnam was already sharing daily data, making it (alongside Thailand) one of two Mekong countries that voluntarily published daily dam status before external pressure. In practice, EVN news articles appear at least once per day for major northern reservoirs during operational events; during flood seasons, multiple updates per day are common. The score is limited because updates are bundled inside narrative news articles rather than structured time-stamped records, and there is no guaranteed publication schedule.

Vietnam has published inter-reservoir operation procedures through Prime Minister decisions and government decrees: the Red River inter-reservoir operation rules have been amended multiple times (most recently under Deputy PM Tran Hong Ha's decision), and Decree 114/2018/ND-CP on dam and reservoir safety management is publicly available. Resolution 12/2026/NQ-CP (effective May 2026) establishes emergency operation procedures. These legal instruments describe operational targets (e.g., end-of-season storage levels, minimum downstream flows) but do not constitute measurement methodology documentation. The instruments used to measure water level, the rating curves used to convert level to storage volume, calibration procedures and uncertainty estimates are not published. NCHMF issues hydrological forecasting bulletins but these reference measurement outputs rather than underlying methods.

EVN maintains a full English-language website (en.evn.com.vn) including a dedicated 'Hydropower reservoir's water level' section in English. English news articles on reservoir status events are published regularly, confirming that at least the major dam operational situations are communicated to international audiences. However, the routine daily water level bulletin articles are published in Vietnamese only; the English section carries translated highlights rather than systematic daily data. NCHMF's public forecasting site (nchmf.gov.vn) has an English interface but no reservoir data. MONRE and NAWAPI portals are Vietnamese-only. The MRC portal (mrcmekong.org) provides English-language basin data including Vietnamese sections. Overall: partial English accessibility for high-profile events, but routine operational data is Vietnamese-only.