Paraguay Reservoir Transparency

Both reservoirs in the covered subset are reported daily. EBY (Yacyretá) publishes a daily executive summary (Resumen Ejecutivo) on eby.gov.py that includes current reservoir cota in msnm, 24-hour inflow forecasts, spillway status, and downstream port levels — confirmed at cota 82.85 msnm on 2026-05-18 (bulletin #5962). Itaipu Binacional publishes a daily hydrological bulletin as a PDF (BH.pdf) on itaipu.gov.br covering the Paraná River downstream, and periodic news articles reporting current embalse levels (e.g. 219.41 msnm average for Dec 2025; 220.08 msnm in 2026). The CIH/YRATO platform (hidroinformatica.itaipu.gov.py/yrato/) monitors hydrometric stations with documented endpoints for cota, caudal, and volume. However, no dedicated machine-readable dataset for reservoir storage volumes is published by any Paraguayan national agency. ANDE publishes no reservoir data online. Score is lifted by EBY's consistent daily publications and Itaipu's PDF bulletin.

EBY's daily Resumen Ejecutivo is published as plain HTML on eby.gov.py — machine-parseable in principle but not structured data: no CSV, JSON, or API. Each bulletin is a separate WordPress-style post with the cota value embedded in the post title and body text. Itaipu's BH.pdf hydrological bulletin is a PDF requiring scraping or manual reading. The CIH/YRATO platform documents a public REST API (hidroinformatica.itaipu.gov.py/docs/) returning JSON for hydrometric stations including cota, caudal, and volume, with no registration required — this is the most technically accessible component, but covers river monitoring stations rather than the Itaipu reservoir itself as a discrete storage body. datos.gov.py contains no reservoir datasets. Overall: no structured open data, no standard download formats for reservoir volumes; access relies on PDF parsing or HTML scraping.

Methodology v1.3.0 (capacity-weighted). Total Paraguayan national reservoir storage capacity is approximately 29,000 hm³ in the two binational hydroelectric impoundments on the Paraná River — Itaipu (~29,000 hm³ total; ~3,400 hm³ useful) and Yacyretá (~21,000 hm³ total; ~2,580 hm³ useful), with Paraguay's share of Itaipu jointly with Brazil and of Yacyretá jointly with Argentina. Covered capacity through EBY (Yacyretá daily Resumen Ejecutivo) and Itaipu Binacional (BH.pdf daily bulletin + news releases, with additional data through Brazil's ONS) is the full national capacity. Coverage = round(100 × 29,000 / 29,000) = 100. Paraguay has no other reservoirs crossing operational significance; all other water storage is in small irrigation/livestock tajamares and natural Pantanal/Chaco wetlands.

Scoped to the 2 covered reservoirs, historical depth is moderate and asymmetric. EBY's Resumen Ejecutivo series was numbered at #5962 on 2026-05-18; at one bulletin per day, this implies the series started approximately in late 2009 or early 2010, giving roughly 16 years of daily cota records for Yacyretá accessible on the eby.gov.py website — though they are published as individual HTML posts, not as a bulk download or time-series file. Itaipu historical data is accessible through Brazil's ONS back to the mid-2000s (~20 years) and through the reservatoriosBR R package, but this is a Brazilian rather than Paraguayan data publication. Paraguay's DMH (Dirección de Meteorología e Hidrología) publishes annual hydrological yearbooks (2020–2024) as PDFs, covering river levels but not dedicated reservoir storage volumes. Median historical depth across the 2 covered reservoirs is approximately 16 years.

EBY publishes a Resumen Ejecutivo daily for Yacyretá (confirmed for weekdays in May 2026, with sequential numbering showing no gaps), containing that day's cota reading at 06:00 hrs and the previous day's level. Itaipu publishes a daily hydrological bulletin (BH.pdf), updated daily including weekends and holidays. The CIH/YRATO platform updates precipitation data every 30 minutes from GPM-NASA satellites. DMH publishes daily river level bulletins for the Paraguay and Paraná rivers. Update frequency for operational levels across the 2 covered reservoirs is therefore effectively daily. Score is penalized because this high frequency exists only in HTML/PDF form — no sub-daily programmatic data feed for reservoir storage — and ANDE publishes nothing.

Itaipu Binacional's Technical Direction (Dirección Técnica) has published some technical reports — including engineering studies on operating levels (e.g. Report GT.T-03 on raising the maximum cota from 220.50 to 221.50 msnm) and references to the 1983–2021 historical average series — indicating internal methodological standards exist. EBY's daily bulletins cite the Operations Sector (Sector de Operaciones, Departamento Técnico) as data source and reference climate indices (Niño3.4, SOI, IOD) with standard meteorological methodology. However, neither institution publishes explicit documentation of their measurement instrumentation, calibration procedures, quality-control protocols, or datum/benchmark references in a publicly accessible technical manual. Paraguay's DMH does not publish methodology for reservoir-specific measurements. No ISO or WMO-standard methodological documentation is publicly linked.

All primary Paraguayan sources — EBY's daily bulletins, Itaipu's itaipu.gov.py, DMH publications, and datos.gov.py — are exclusively in Spanish (and occasionally Portuguese for the Brazilian side of Itaipu). Itaipu Binacional redirects its English-language subdomain (itaipu.gov.br/en/) to itaipu.energy, a promotional rather than data-oriented site. The CIH/YRATO API documentation is in Spanish. No English-language data access portal, bulletin, or download exists from any Paraguayan institution for reservoir data. International researchers must navigate Spanish-only interfaces, decode embedded cota values in HTML post titles, or rely on the Brazilian ONS/reservatoriosBR ecosystem for Itaipu data in a more accessible form.