Danube River oxygen-regime monitoring and Streeter–Phelps forecast data, Ukraine, 2004–2023

This dataset contains dissolved oxygen and five-day biochemical oxygen demand (BOD5) monitoring data for four stations on the Ukrainian section of the Danube River: Reni, Izmail, Kiliya, and Vylkove. The study period is 2004–2023. The package includes 787 observation-level records selected from the author-supplied monitoring workbook, annual average values, cold-season and warm-season annual averages, observed and predicted annual values from the Streeter–Phelps model, model coefficients for three river sections, and forecast-accuracy metrics. The monitoring stations are Post_ID 27269, Reni; Post_ID 27270, Izmail; Post_ID 27271, Kiliya; and Post_ID 27272, Vylkove. The cold season is defined as November–March and the warm season as April–October. Two author-supplied Excel workbooks are preserved unchanged. The workbook prepared for the article was used as the authoritative source for processed annual, seasonal, and forecast tables because some values differ between the analytical and publication versions. Primary monitoring source: State Agency of Water Resources of Ukraine, State surface-water monitoring data.