The line graph illustrates the proportion of river water quality in the UK from 1990 to 2002.
Overall, there was an upward increase in the percentage of good chemical quality in these nations in the UK, with the exception of Wales over the span of 22 years. Notably, both Wales and Northern Ireland led as the top two countries in the UK having good water quality in rivers.
Looking at Wales and Northern Ireland, both remained stable in the first 8 years of the period, at 95 % and 85% respectively. Subsequently, there was a considerable decline to 80% in the quality of river water in Wales in 2002 after getting the same proportion with Northern Ireland at 90% in 1998, while Northern Ireland experienced a moderate rise to 95% in river water quality, regarding as the country having the best quality of water rivers in 2002.
In contrast, England and Scotland had the quality of river water below 50%, standing at 45% and 22% respectively in 1990, before rising significantly until 1996. From then on, the water quality in Scotland continued to climb to nearly 60% in 2000 after having the same quality as England in 1997 and finally decreased to 40% in 2002. Meanwhile, England saw a sharp decrease to 30%, before reaching around 50% in 2002.