The line graph illustrates the proportion of water in the rivers of Wales, Northern Ireland, England, and Scotland that was categorised as possessing good chemical quality from 1990 to 2002.
Overall, it can be seen that except for Wales, all areas recorded some growth over the given duration, despite facing fluctuations. Additionally, initially, Wales was the leading category, while by the end of the given time frame, Northern Ireland surpassed Wales.
Between 1990 and 1998, Wales and Northern Ireland ran parallel, with Wales rising moderately from approximately 95% to 97%, while Northern Ireland increased from a relatively lower figure of almost 85% to 87%. However, from 1998 to 2002, Wales followed a downward trajectory to end the period at about 80%, whereas Northern Ireland grew considerably to just below 100% by 2002.
Moreover, Scotland experienced a growth of around 40% between 1990 and 2000, rising from just above 20% to 60%. By contrast, the figure decreased sharply to 40% by 2002. Furthermore, England accounted for approximately 45% in 1990, which grew moderately to almost 70% by 1996. Conversely, the figure plummeted to 30% between 1996 and 1998 before growing significantly to reach 50% by 2002.