“After the council unanimously supported the Rivers and Oceans Motion last year, it’s essential to keep this conversation alive and push for real change,” he added.
McDermid said tackling pollution would require cooperation from the community, local groups and government.
“This is a problem of such scale it cannot be tackled alone,” he said.
“We want everyone to be able to enjoy our rivers long into the future, and working together we can make that a reality.”
The council’s Water Improvement Group said it was working to identify pollution sources, monitor water quality and involve local people in caring for the district’s waterways.
The exhibition comes after a £1m fund to investigate the sources of pollution in the River Wye was announced by the Welsh and UK governments.