Proceedings

The intake protection monitoring for the River Dee commenced after a phenol incident in 1984 affected
the supply to over two million customers in North East Wales, Cheshire, Shropshire and the Wirral. In
2007 a review of monitoring arrangements to protect public water supply abstractions owned by United
Utilities, Dwr Cymru Welsh Water and Dee Valley Water was carried out for the Dee Steering Committee.
The monitoring regime was reviewed to align with components of the drinking water safety plans
required by the Drinking Water Inspectorate. A catchment risk assessment model was also produced,
using spreadsheets and a Geographic Information System to enable assessment of the risks into the
future. This catchment risk assessment considered potential interruptions to public water supplies based
on pollution sources such as: land use, industrial activity, chemical storage and pesticide usage. The
findings of this study have been used to revise the existing monitoring strategy and prepare for responses
to pollution incidents protect potable water supplies.

Key words
Catchment risk assessment model, Intake protection, Monitoring, Pollution, Drinking water safety plan,
Potable water abstraction.