Costa Rica Reservoir Transparency

CENCE publishes real-time water levels (msnm) for four major reservoirs — Arenal, Cachí, Pirrís, and Reventazón — via its publicly accessible Boletín Intra-Diario, updated every 15 minutes via SCADA. No registration is required to view the dashboard. However, data is expressed as water surface elevation (metres above sea level), not volumetric storage (Mm³), so usable storage cannot be derived without a level-area-volume curve that is not publicly provided. Annual DOCSE reports (PDF) describe electricity generation and Arenal levels qualitatively but do not publish machine-readable storage time series.

The Boletín Intra-Diario is a JSF web application with no documented public API or structured download endpoint for reservoir data. The CENCE portal mentions 'Servicios Web' but provides no public documentation or open endpoint for embalse levels. ARESEP exposes a REST API (datos.aresep.go.cr) covering electricity generation from 2004 to present, but it contains no reservoir storage or level data. Electricity generation data (CSV/JSON/XML) is downloadable from the GeneracionReal page, but reservoir level series are not. Programmatic access to historical reservoir levels requires custom scraping of the bulletin interface.

Strictly linear under v1.2.0: n_covered = 4 ICE-operated reservoirs (Arenal ~1,990 Mm³ useful, Cachí, Pirrís, Reventazón) appearing in the CENCE public SCADA dashboard. n_total ≈ 6 reservoirs above 10 hm³ in Costa Rica per AQUASTAT and ICE inventory — Angostura (17 Mm³, not in the public bulletin), plus one or two smaller hydro/water-supply reservoirs (e.g. Río Macho ancillary storage). Coverage = round(100 × 4/6) = 67. The covered subset includes the dominant regulation reservoir (Lake Arenal supplies ~20% of national electricity) and the cascade reservoirs critical for system dispatch. The uncovered ~2 are mid-sized facilities without a public real-time interface.

The Boletín Intra-Diario shows only the current snapshot with no historical query interface — it is a live bulletin, not an archive. Annual DOCSE PDF reports are publicly available on the CENCE portal from 2021 to 2025 (five years), and they include narrative descriptions and graphics of Arenal reservoir levels by year. Earlier annual reports appear not to be hosted on the current portal. No machine-readable historical time series of reservoir levels (daily, monthly, or annual) is available for public download. ICE records are cited in academic sources going back to the 1979 commissioning of Arenal, and rainfall records to 1958, but this data is not publicly accessible online in structured form.

The CENCE SCADA system acquires reservoir level readings every 15 minutes, and these are reflected in the publicly viewable Boletín Intra-Diario. This is an exceptionally high update frequency for a public dashboard. However, the bulletin carries the explicit disclaimer 'not used for commercial measurement', and no data retention or historical access is provided through the same interface. ARESEP's electricity generation API is updated monthly. Annual PDF reports are published once per year.

No publicly documented methodology exists for how SCADA water-level readings are converted to usable storage volumes, nor is any level-area-volume (hypsometric) curve published for the four monitored reservoirs. The bulletin itself notes data is 'not used for commercial measurement', implying formal metrological standards are internal only. ARESEP regulatory filings reference generation and installed capacity but do not publish reservoir measurement standards. No bathymetric surveys or measurement protocols for Arenal, Cachí, Pirrís, or Reventazón are available on public portals. ICE's annual reports include some hydrological context but do not describe sensor calibration, quality control, or uncertainty estimation.

All ICE/CENCE portals, bulletins, annual reports, and the ARESEP open data platform are exclusively in Spanish. No English-language interface, API documentation, or translated data portal exists. ICE publishes a brief energy matrix brochure in English (PDF), but this contains no data on current reservoir levels. International researchers must navigate Spanish-only JSF applications with no language toggle. SINIGIRH and other government water portals are similarly Spanish-only.