The line graph illustrates the proportion of water in UK rivers that divided four countries as having good chemical quality water namely Wales, Northern Ireland, England and Scotland changed between 1990 and 2002.
Overall, the high percentage of positive chemical quality water were Wales and Northern Ireland. However, the opposite was true with England and Scotland. The proportion of water quality remained stable long time in the Wales and Northern Ireland.
To begin with the bigger proportion of river water quality water in the United Kingdom. The Wales was considerable higher good chemical quality water among three countries roughly at 95% in 1990, and it remain unchanged until 1998. After then Wales got the second place with decreasing to 80% in 2002. Conversely, the Northern Ireland also showed some similar patterns like the Wales. The percentage of water quality was same at about 86% between 1990 and 1998. The figure for water quality slightly increased to 95% from 1998 to 2002.
In terms of England, it experienced different patterns every two years. Starting with river water quality, considerably increased from 45% to 70% between 1990 and 1996. However, sharply decreased to 30 % in 1998, then again rose to 50% in final year. When it comes to Scotland was lowest percentage of good water quality in river. The Scotland grew from 22% to 60% in ten years. By contrast, despite of increasing, good chemical quality decreased at 40% between 2000 and 2002.