The line graph illustrates the percentage of water in UK rivers classified as possessing good chemical quality from 1990 to 2002 across four regions: Wales, Northern Ireland, England, and Scotland.
Overall, Wales and Northern Ireland exhibited relatively high and stable levels of water quality, whereas England and Scotland experienced marked fluctuations throughout the period.
In 1990, Wales and Northern Ireland recorded approximately 95% and 60% of water deemed chemically sound, respectively. Wales demonstrated an upward trajectory, peaking at about 99% around 1994 before experiencing a decline to about 95% in 2002. Northern Ireland, meanwhile, initially improved to nearly 90% by 1994 but faced a sharp decline back to approximately 60% in 1996. Subsequently, it regained ground to about 90% by 2000 before encountering another significant drop to nearly 70% by the end of the period.
Contrastingly, England and Scotland began with figures of just above 70% and just under 90%, respectively, in 1990. England witnessed a decline to around 60% in the mid-90s before recovering slightly to approximately 70% by 2002. Scotland experienced a gradual decrease throughout the period, beginning at about 87% and finishing near 80% in 2002, which indicates a sustained decline rather than improvement. In comparison, the fluctuating trends in England and the steady deterioration in Scotland reveal significant variations in water quality management within these regions.