page_title: Watersheddles Reservoir
section_title: Hydrometry
hierarchical_section_title: Watersheddles Reservoir / Hydrometry
context_page_description: Watersheddles Reservoir is an upland artificial lake in Lancashire, England. The reservoir was opened in 1877 by the Keighley Corporation Water Works, and is now owned by Yorkshire Water. It supplies water to the Worth Valley and Keighley area and compounds several streams at the source of the River Worth.
  Although the reservoir is just across the boundary of Lancashire, all of the water is used in the West Yorkshire region.
  Due to the peatland in the immediate catchment area, the reservoir is prone to a high acidity and discoloration in its water.
context_section_description: Water from the reservoir is sent to a water treatment works (WTW) at Oldfield on the north side of the Worth Valley. Oldfield WTW also receives water from Keighley Moor Reservoir, and between the two, they supply over 1,800,000 imperial gallons; 2,100,000 US gallons (8,000,000 L) per day. Oldfield was opened in 1891 in an effort to treat the water from the reservoirs as the acidic water was eating into the pipes and poisoning the water with lead. A report from 1897 relays how the water is cleared through limestone, coke, sand and "polarite", but suffered from discolouration arising from peat sediment settling on the bottom of the reservoir. In 1973, just before Yorkshire Water assumed control of Watersheddles and Oldfield WTW, the pH of water arriving at Oldfield was registered as being between 6.9 and 7.0.
  The waters entering the reservoir drain a peat moorland with millstone grit underlying. The water was recorded with a pH value of 4.1 in 1988 and has been noted for its 'colour', which takes a more intensive process to remedy at the WTW. The problems of the pH value at Watersheddles (and to an extent, Keighley Moor Reservoir) were so bad, that Yorkshire Water designed and built their own prototype triple-pH controller in 1988 to regulate the waters acidity.
  In the late 1890s and early 1900s, a rain gauge was sited at Watersheddles, the results of which are given below;
  The water at the reservoir between 2013 and 2016 was assessed as moderate for ecological quality and good for chemical quality.
caption: A schematic of the Worth Valley reservoirs and their drinking water supply.  All reservoirs feed the River Worth - Watersheddles and Ponden directly and Keighley Moor and Lower Laithe by North Beck and Sladen Beck respectively.[30]