History of the Huddersfield Water Supplies
By T. W. Woodhead

CHAPTER IV - WATERWORKS COMMISSIONERS

CENTRAL PENNINES AS AN AREA OF SUPPLY.
CONDITIONS IN THE CATCHMENT AREA.

The County Borough has a wide range of altitude – from 150 feet at Colne Bridge, to 1,244 feet above sea level at Scape Goat Hill. To meet the requirements for water, it was necessary to have a heading and storage capacity sufficient to deliver a water supply to all who needed it within that area. In addition provision had to be made for a supply to numerous villages outside the County Borough, making a total area of 51,824 acres (See Figure 32 below).

Figure 32. Catchment Area (click on image for larger map)

As we have seen, the neighbouring Pennine hills attain in our District an altitude of 1,909 feet O.D. at Black Hill, have a mean annual rainfall of fifty to sixty inches, and provide many sites for collecting reservoirs and gravitational supplies. With such a rainfall, we seldom suffer from variable and uncertain flow. Our chief sources of supply are from the direct run-off on these high peat-clad moorlands, and from the numerous springs issuing from the valley sides, especially between the permeable sandstones and impermeable shales and at the fault scarps.

As we have seen above the geological structure of the Central Pennines determines largely the quality of the water derived from the area and this in turn has had an important influence on the origin and development of our local industry. The rocks are mainly siliceous and sandstones and are very deficient in lime ; further these beds are covered by enormous deposits of peat, which not only discolour the water but render it acid. How some of these conditions effect local needs may thus be illustrated.

As a rule water from the Millstone Grit area is very soft, and on the whole this is of great advantage to our local textile trade. The sandstones commonly contain grains of felspar – a complex silicate of alumina and an alkaline base. When this decomposes, soluble alkaline silicates are produced which readily exchange acids with any lime or magnesia, resulting generally in insoluble silicates also carbonates and sulphates of soda.

Such waters are much desired for wool scouring and for dyeing in certain colours. In the former it economises soap and in the latter, in some cases, it prevents the deposit of an insoluble crust on the fibre which if produced would result in an uneven dye. In other cases it economises the dyestuff and may supply an indispensable adjunct. On the other hand a soft water is detrimental to certain dyes, and hard water if necessary.

Occasionally the water from the grits may show a considerable degree of hardness, as at Rake Dike, near Holme, where in 1922 a party of botanists discovered on the wet dripping rocks by the stream, a moss (Hypnum commutatum Hedwig) and a liverwort (Pellia Fabbroniana Raddi), which are usually confined to a calcarious soils. Mr. W.H. Burrell, who made the discovery, examined the water issuing from the rocks at this point and found it to contain 9-10 degrees of hardness. Mr. C.E.N. Bromehead, of the Geological Survey, on being notified of the find, was at once able to identify the exact locality as the outcrop of a bed of fossil goniatites of the marine band mut. B. The normal stream of water of the district gives only 3 or 4 degrees less.

The deep deposits of cotton-grass peat provide an important check to the run-off, and the water absorbed by the spongy peat is released slowly during dry periods and thus conserves the supply.

The cloughs leading from these peat moors contain scattered remnants of oak-birch forest and their story is one of long and steady decay. In the days prior to and during the Industrial Revolution, much timber was cut from these woodlands to meet local needs, and in the absence of replanting, long stretches of these clough sides have become treeless and are not covered with extensive sheets of bracken.

The clough and moorland slopes would be suitable for replanting, but the Pennines as a whole, especially the peat covered plateau, cannot be regarded as suitable for the growth of timber on economic lines, though as shown in the Museum Handbook, No.5, forests were formerly extensive in areas which have long been treeless and are now useless for afforestation which have proved unsuccessful ; in part owing to exposure of the small area planted.

The Forestry Commissioners, as well as many Waterworks Authorities, realize the importance of woodland in catchment areas, and attempts are being made in many places to re-afforest these bracken and heath covered valley sides. Among the advantages of a tree covering, the following, as indicated by Mr. A.P. Long, of the Forestry Commission, may be mentioned. Transpiration from the leafy canopy increases humidity, heat is absorbed during evaporation, and the foliage cannot become heated to the same extent as the bare soil, which is thus protected ; hence the temperature is lowered in and above the forest. Moisture-laden currents on meeting these conditions tend to precipitate more of their moisture in the neighbourhood of the forest and so increase the yield in the catchment area. This is the case at least with large tracts of forest. Evaporation from soils is less in the forest than in the open ; the leafy canopy breaks the fall of rain ; the humus layer absorbs and delays run-off, and water from the forest is less acid than that coming from the peat. The seepage water from the peat, making its way down the valley sides, when reaching the forest, becomes entangled in the humus, thus checking evaporation and increasing natural filtration. The roots of trees render the soil porous, permit absorption to the deeper layers and so replenish the springs ; hence a better distribution of the run-off which is important when the bulk of the run-off has to be conserved in reservoirs. Forests also reduce soil erosion and thus reduce silting.

It is on these grounds that forests have, in general been regarded as the ideal vegetative cover for important catchments. The spruce, however, so favoured by our foresters on economic grounds, is alien to our moorland cloughs. On the other hand, the planting of hard woods in the proximity of reservoirs is in danger by blocking with hard wood leaves. The Forestry Department is not only prepared to give advice as to lay out, selection of trees and establishment of a nursery, where forestry schemes are contemplated, but they will also give grants.

This water from the peat-clad moors and moorland cloughs is collected into reservoirs by the impounding of streams from the uplands, by the construction of dams across the narrow moorland valleys, and the water from tributary streams is drained into conduits which convey the supply to the impounding reservoirs. The steep and narrow valleys draining our catchment areas, however, do not admit the construction of reservoirs of large size as compared with sites available for some other towns, in consequence we have to resort to many reservoirs of relatively small size, necessitating numerous filter stations, with their attendants, resulting in increased cost of construction and supervision.

As stated above, the water impounded in the storage reservoirs for domestic and trade supplies, is diverted from its natural course, and riparian owners and occupiers down stream are placed at a disadvantage. Further, in every valley suggested by the Corporation for reservoir constructions, riparian owners had already made reservoirs for use in the factories and works below. In consequence an agreed volume has to be liberated daily from these new collecting reservoirs as compensation. This, however, had the advantage of maintaining a more regular supply for users, especially in times of drought.

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