CHAPTER VII 
THE AFFORESTATION OF WATER CATCHMENT AREAS 
THE afforestation of water catchment areas is a hygienic 
measure as well as a means of increasing the timber reserves 
of the nation, as will be shown after some preliminary 
observations on the water supply of our great municipalities. 
Some towns get their water supply from large rivers, as 
London from the Thames and Aberdeen from the Dee. 
Other towns are supplied by springs, wells, and deep borings 
of various kinds. The third method, which specially 
concerns us, is that of catchment reservoirs, constructed to 
impound the water falling on upland and sparsely peopled 
tracts. Such gathering grounds in the Pennine range 
supply most of the great centres of population in 
Lancashire, Yorkshire, and Derbyshire. Other catchment 
areas are situated in Wales, Cornwall, and a few other 
districts in England, and in many parts of Scotland. 
Natural lakes, often made larger by artificial dams, as 
Loch Katrine used by Glasgow and Thirlmere by Manchester, 
are in the same category as artificial reservoirs, and like 
these derive their water supply from the drainage of the 
surrounding watersheds. 
In many cases the water authorities have only leased 
the water rights and have not acquired the ownership of 
the gathering grounds. For the prevention of pollution 
of the water, they have relied mainly on the 61st Section of 
the Waterworks Clauses Act of 1847, which makes it penal 
to lead sewage into, or wantonly to defile, the reservoirs 
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