§ Mr. Hardy
asked the Secretary of State for the Environment (1) what is the number of rivers and the miles of river involved which need improvement before the water contained can be extracted for domestic consumption;
(2) if he will estimate the total amount of water which could be provided for domestic purposes if those rivers currently in a condition of gross pollution were improved to a satisfactory and wholesome standard;
(3) if he will name the 20 dirtiest rivers in England and Wales in order of most unwholesome pollution;
(4) what is the number of rivers and the miles of river involved in England and Wales which are classified as being grossly polluted; and what is the proportion which is being improved to a wholesome standard at the present time.
§ Mr. Graham Page
I would ask the hon. Member to await publication of the Report of the River Pollution Survey—the first volume around the end of the year, the second volume about three months later.
Maps accompanying the first volume will show into which of four classes, ranging from unpolluted to grossly polluted, each stretch of each river falls; and tables in the same volume will show, 387W for England and Wales and for each river authority, the miles of river falling into each class.
Not all rivers will be needed in the foreseeable future as sources of domestic water supplies; but the second volume will show how many miles of river which are unsuitable as sources now will become suitable in future if discharges achieve the standards which river authorities expect to require; and other tables will show the mileages of river changing their classification as a result of the achievement of those standards. The first volume will also give an indication of the overall improvement since 1958.
I do not think it is useful to estimate the additional quantities of raw water, suitable after conventional treatment for domestic supply, which might be got by restoring all grossly-polluted rivers to an unpolluted condition. It would mean making a large number of assumptions about such things as the acceptable frequency of re-use and the availablity of land for reservoirs to even out seasonal flows. It is better that, as in the current study of the river Trent, such possibilities should be evaluated for individual rivers in comparison with alternative methods of obtaining additional water.
§ Mr. Graham Page
Particulars will be given in the report of the recent comprehensive survey of rivers, the first part of which will be published shortly. The aim of the survey is to enable assessments to be made of what needs to be done and of the relative urgency of the various works needed, and this is in hand.