234 FORESTS, WOODS, AND TREES 
removed. This catchment area could probably be afforested 
with profit, and in any case ought to be owned by the Council. 
The Wrexham and East Denbighshire Water Company 
obtain their supply in part from the Pentrebychan Brook, 
with a gathering ground of 1500 acres, on the Esclusham 
Mountain, between 900 and 1500 feet elevation. The 
ground, none of which is owned by the Company, is all 
barren moorland on millstone grit and limestone, without 
houses or farmsteads. There is said to be no possible 
contamination. The water is first settled in an impounding 
reservoir at Cae Llwyd, Esclusham Above, then decanted 
into the Ty Mawr reservoir and finally filtered through 
slow sand filters. 
Birkenhead obtains its water supply at present from 
wells and borings in the New Red Sandstone formation ; 
but an additional source of supply from a gathering ground 
of 6300 acres on the head-waters of the river Alwen in 
Denbighshire was authorised by the Birkenhead Corporation 
Water Act of 1907; and the necessary works, including 
reservoir, mechanical filters and tanks, are now being con- 
structed. The Alwen catchment area is situated between 
1190 and 1760 feet elevation, and consists mainly of 
moorland, more or less covered with peat, which varies in 
depth from a few inches to many feet. Below the peat on 
the south and west is generally boulder clay; elsewhere rock 
and shale prevail. About 550 acres only may be classed 
as arable and grass land, there being a little cultivation on 
the north and east sides of the watershed, and about 
100 acres of woods and plantations on the north-east side 
of the valley. There are eleven houses and farmsteads on 
the gathering ground, five of which belong to the Corpora- 
tion; and of the latter, two near the margin of the reservoir 
will probably remain uninhabited. 
The Corporation own 2600 acres, including some land 
below the reservoir, that drains to the river Alwen. Of 
this area, about 375 acres are covered with the water of 
the reservoir. Prof. Fraser Story estimates that about 
