Concentration of BOD5 in rivers in different countries between 1992 and 2005, shown in consequent time intervals.

BOD5 data are used for all countries except Estonia, Latvia (1996-2001) and Lithuania (1996-2005) with BOD7 data. BOD7 data were recalculated into BOD5 data. Concentrations are expressed as median of annual average concentrations. Data are from representative river stations. Stations that have no designation of type are assumed to be representative and are included in the analysis. Time series are averaged for the 4 consequent time periods 1992 to 1995, 1996 to 1999, 2000 to 2002 and 2003 to 2005 (see Methodology section for further details). Consistent time series trends are available for Austria, Bulgaria, Czech Republic, Estonia, France, Hungary, Latvia, Lithuania, Slovakia, Slovenia and United Kingdom, except for Denmark (2005) and Luxembourg (2003) with one year missing and Macedonia FYR with missing data for 1996-1999 period. Data for each year within 1996-2005 period are available for Poland and Belgium, within 1996-2002 for Ireland with one year missing (1996) and within 2000-2005 period for Spain, Greece and Italy with one year missing for Greece (2005). For Bosnia and Herzegovina, Croatia and Serbia and Montenegro data are available for one time period, 2000-2002 and 2003-2005 respectively with one year missing for Serbia and Montenegro (2003).