Poland Reservoir Transparency

Scoped to the COVERED subset (~50 reservoirs published by IMGW Hydroportal + Wody Polskie). IMGW's hydro.imgw.pl presents daily readings (water surface level, inflow, outflow, characteristic capacities) for retention reservoirs entered by their administrators. Wody Polskie publishes a daily bulletin on filling status for 52 key flood-control / retention reservoirs as HTML/PDF. Storage volumes (Mm³) and fill percentages are visible per-reservoir, but the daily bulletin is unstructured for machine ingestion, and reservoir data entry depends on individual administrators creating intermittent gaps. The typical covered reservoir has daily fill data published.

For the COVERED subset: IMGW provides a documented public JSON/CSV/XML REST API at danepubliczne.imgw.pl/api/data/hydro returning current hydrological station readings (water level, flow), and historical bulk CSV/ZIP archives. INSPIRE-compliant OGC SOS 2.0.0 and WFS 2.0.0 services exist. However, the REST API covers gauge stations rather than exposing reservoir storage volumes as a clean dedicated endpoint — reservoir-specific fill percentages and storage volumes are only available via the Wody Polskie HTML/PDF daily bulletin or by scraping the hydroportal map interface. Programmatic access to the covered reservoir storage data requires either scraping or use of the authenticated CPA API. Structured downloads with partial API coverage is the dominant access mechanism.

Methodology v1.3.0 (capacity-weighted), conservative denominator. Reported Polish reservoir capacity per IMGW/Wody Polskie key-reservoirs registry is approximately 3,500 hm³, dominated by Solina (~472 hm³, the largest), Włocławek (~370 hm³), Jeziorsko (~202 hm³), Goczałkowice (~166 hm³), Czorsztyn-Niedzica (~232 hm³), Nysa (~124 hm³), Otmuchów (~131 hm³), Dobczyce (~127 hm³), Sulejów, Mietków, Sosnówka, Klimkówka, Świnna Poręba and the rest of the ~47 'key' reservoirs. Applying a +15% conservative uplift to account for pumped-storage upper reservoirs (Żarnowiec, Porąbka-Żar, Niedzica/Czorsztyn upper basin, Solina-Myczkowce), industrial cooling reservoirs serving Bełchatów/Pątnów/Konin coal complexes, private and municipal supply reservoirs in Lower Silesia and Lesser Poland not in the Wody Polskie operational system, plus mining-sector storage above the 10 hm³ threshold, the realistic denominator is approximately 4,000 hm³. Covered capacity through the Wody Polskie operational system and IMGW publication of ~50 reservoirs is approximately 2,800 hm³. Coverage = round(100 × 2,800 / 4,000) = 70. The residual gap is pumped-storage facilities, industrial cooling reservoirs and a long tail of non-flood-control structures at the lower end of the threshold.

MEDIAN years across the ~50 covered reservoirs: IMGW-PIB's Central Hydrological Database holds continuous discharge and water-level series, and reservoir-specific storage volume time series for the covered set are generally available from approximately 2000 onwards. Annual hydrological yearbooks (Rocznik Hydrologiczny) document this data publicly back to at least 2018 in PDF form. For the typical covered reservoir, structured fill-percentage data spans approximately 15–20 years, placing the median in the 10–20 year band. Some older gauge records extend to 1951–1971 for one-third of stations, but the median digitised reservoir-specific archive is ~20 years.

For the COVERED subset: the IMGW-PIB hydro portal updates river gauge data hourly in near-real-time. Reservoir-specific data (water surface level, inflow, outflow) is updated daily for the covered set, with entries submitted by individual reservoir administrators and collated at 06:00 UTC. Wody Polskie publishes a daily flood-reservoir bulletin each morning. Daily refresh applies to >50% of covered reservoirs.

For the COVERED subset: IMGW-PIB publishes annual hydrological yearbooks (Rocznik Hydrologiczny) that document measurement methodology, station characteristics, and statistic derivation; freely available 2018–2024. Reservoir capacity figures are published in Wody Polskie's SIGW system. INSPIRE metadata is partially available via imgw.isok.gov.pl. However, capacity measurement methods (bathymetric survey dates, sedimentation correction), uncertainty ranges, and data quality flags are not consolidated in a single public metadata record for the covered set.

All primary data portals (hydro.imgw.pl, danepubliczne.imgw.pl, Wody Polskie daily bulletin, SIGW, Hydroportal) are Polish-only with no English toggle. IMGW-PIB's English institutional site (imgw.pl/en/) does not link to data portals. API field names and CSV column headers are in Polish. INSPIRE metadata catalogues include some bilingual entries per requirement, but no English data dictionary exists for reservoir-specific fields.