How did the average pH of Lake Erie change from 1990 to 2015?

The average pH of Lake Erie has been gradually increasing from 1990 to 2015. This is due to efforts to reduce pollution and improve water quality in the lake. In 1990, the average pH of Lake Erie was around 7.2, and by 2015, it had increased to around 8.2. This increase in pH is a positive sign of the improving health of the lake ecosystem.