Iceland Reservoir Transparency

For the COVERED subset (6 large Landsvirkjun reservoirs published in the rauntimavoktun portal launched July 2025 — Þórisvatn, Hálslón, Blöndulón, Sultartangalón, Krókslón and Vatnsfellslón), publication is consistent: current water levels in metres above sea level, current-year and previous-year traces plus historical average/extreme bands. Data is expressed as water elevation rather than volumetric storage or fill %, so users must source stage-storage references externally to derive operational meaning. No bulk download or API is available, and no official state-level reservoir storage bulletin consolidates the data. Iceland does not report to ENTSO-E Transparency Platform because it operates as an isolated grid.

For the COVERED subset, the dominant access mechanism is an HTML chart on the rauntimavoktun portal. No documented REST API or machine-readable endpoint exists for Icelandic reservoir storage data. The portal offers no CSV/JSON download functionality. The Icelandic Met Office provides a weather observation API (api.vedur.is) but it covers meteorological stations, not reservoir storage. The apis.is community API directory has no water/reservoir endpoints. Data can only be read visually from the Landsvirkjun portal.

v1.3.0 capacity-weighted: coverage = round(100 × covered_capacity_hm³ / total_national_capacity_hm³). Iceland's total reservoir capacity above 10 hm³ is approximately 3,400 Mm³, dominated by Hálslón (~2,100 Mm³) which alone represents ~62% of national storage. The six reservoirs published on Landsvirkjun's rauntimavoktun portal — Þórisvatn, Hálslón, Blöndulón, Sultartangalón, Krókslón, Vatnsfellslón — cover approximately 2,800 Mm³ of qualifying storage. Coverage = round(100 × 2,800 / 3,400) = 82. The capacity-weighted view sharply raises the score because Landsvirkjun's portal captures Hálslón plus the other major Landsvirkjun reservoirs; the uncovered residual consists of small HS Orka and ON Power facilities and minor regulated lakes, none of which materially contribute to national capacity.

MEDIAN history for the COVERED subset is approximately 18–20 years. The rauntimavoktun portal displays the current water year, the previous water year, and historical average/extreme envelopes derived from approximately 2004–2022 for Þórisvatn and 2008–2022 for Hálslón, with comparable reference windows for the other covered reservoirs (Blöndulón since 1991, Sultartangalón since 1999, the newer Hálslón since 2008). Landsvirkjun's internal inflow modelling uses historical records back to the 1950s, but this is the MAX, not the median publicly accessible series. Orkustofnun's annual energy statistics cover capacity and generation back to 1969 in Excel format but do not publish daily reservoir storage. Median accessible series for the typical covered reservoir: ~18–20 years.

For the COVERED subset, the typical cadence is DAILY (the portal is explicitly described as 'real-time' — rauntíma — monitoring, with chart traces updating each operating day). The Icelandic Met Office hydrological network transmits data to servers at least once daily. Because the rauntimavoktun portal cannot be programmatically queried, the exact cadence (hourly vs. daily) is unconfirmed from documentation, but the visible trace granularity is consistent with daily updates. Landsvirkjun financial releases reference reservoir levels at quarterly intervals as a fallback channel.

For the COVERED subset, Orkustofnun publishes documented annual statistics on installed capacity and generation for all Icelandic power stations (Excel and PDF) with series back to 1969. Landsvirkjun's Climate Accounts follow GHG Protocol methodology and are published annually, and the company describes its inflow modelling as using historical series since the 1950s, calibrated annually. However, specific reservoir capacity volumes, measurement methods (bathymetric surveys, stage-volume curves), operational rule curves and uncertainty bounds are not systematically published in accessible open documentation. The portal shows water level in metres but no explicit stage-volume conversion table is publicly linked.

Landsvirkjun's primary English-language website (landsvirkjun.com) is fully bilingual and all news releases and annual reports are in English. Orkustofnun has a full English-language section (orkustofnun.is/en) with English-labelled data downloads. The Icelandic Met Office operates en.vedur.is in English. However, the rauntimavoktun reservoir monitoring portal (landsvirkjun.is/rauntimavoktun) is hosted on the Icelandic-language subdomain and its page titles and labels are Icelandic-only (vatnshæð = water level). There is no English-language real-time reservoir dashboard confirmed.