A minimum flow of 200 million gallons is fixed by law as the amount needed in summer to keep some sort of cleanliness in the lower river; but in January ten times this amount flows away. It is only for a short time in the months of August or September that the natural flow over Teddington Weir—including the water drawn by the water companies—is a little below 423 million gallons daily, and in those months the surplus might be taken from below the weir without affecting the river materially.
If this be objected to, however, there is another remedy available. The Upper Thames may be used as an aqueduct to convey a larger supply, to be derived from neighbouring watersheds or from wells, the water so obtained to be regulated to meet the requirements, enabling a sufficient amount to be run over the weir to keep the lower river in motion at its upper end. Further down, the small but numerous affluents and springs will keep the river in motion, as they are not affected by the Teddington flow, but give a continuous supply to the river. Mr. Topley, the eminent geologist, in his evidence before the London Water Commission, 1892, stated that there are outside the Thames basin large areas from which water could be obtained, such as East Kent, West Suffolk, Norfolk, Hampshire and Wilts.
It is evident that in this way an enormous prospective outlay for a supplementary water supply for London in the near future may be obviated, and that without adding to the existing plant of the water companies the new Water Board may inherit free of cost a future source of supply which will make their purchase of the London Water Companies’ stocks a good investment and a cheap one for the ratepayers.
Rail and Road Communication at Gravesend.
The possibilities of this scheme are not exhausted, as there remains to be mentioned the opening of railway communication across the river by a tunnel under the dam and of road communication by a roadway over the dam. These are clearly shown in the accompanying [Figs. 4, 5 and 6].
Fig. 4.
SECTION OF THE THAMES FROM TEDDINGTON TO GRAVESEND SHOWING PROPOSED PERMANENT MEAN WATER LEVEL AND TIDAL SECTIONS.
