The provided line chart illustrates the percentage of river water classified as possessing good chemical quality in four regions of the United Kingdom over a span from 1990 to 2002.
Overall, Wales demonstrated the most significant improvement, achieving a peak of 100% in 1998, while Northern Ireland began with the highest percentage but exhibited a gradual decline. Conversely, Scotland displayed fluctuations in its percentage, and England consistently registered the lowest figures throughout the period.
In 1990, Northern Ireland recorded a substantial percentage of 60%, remaining stable until 1994 when it slightly increased to 62%. However, from 1996 onward, Northern Ireland’s percentage experienced a notable decline, culminating at 75% in 2002. Conversely, Wales started notably higher at 90% in 1990, with a steady increase that reached 100% in 1998 and maintained that level until 2000, before experiencing a slight decline to 98% in 2002.
Scotland’s performance exhibited considerable volatility, commencing at 40% in 1990 and ascending to 82% in 1996 before declining to 60% in 1998, only to recover slightly to 66% by 2002. In contrast, England’s figures, while consistently the lowest, showed a gradual increase from 80% in 1990 to 92% by the end of the period. This reflects a steady improvement, albeit insufficient for it to match the higher percentages recorded by the other regions.