Editing River Douglas, Lancashire (section)

==Hydrology==
The reservoirs of the Rivington Chain capture and store run-off from Winter Hill and Rivington Moor, much of which is used to provide a public water supply to areas of Lancashire and Greater Manchester. However, as a result of the original statutes that allowed them to be built, the water company is required to maintain some flow in the river below the reservoirs, and this compensation flow provides a fairly steady baseline flow in the river throughout the year. It is only normally exceeded if the reservoirs become full.{{sfn |CAMS |2013 |p=15}} On the upper reaches of the Douglas, the river bed is relatively steep, and consequently the river level can change quickly as a result of rainfall. As the river progresses to the west, the gradient lessens, and level changes occur more slowly.{{sfn |CFMP |2009 |p=4}}

There are two locations on the river where water is abstracted to maintain levels in the Leeds and Liverpool Canal. On many sections of the river, flows are augmented by the discharge from sewage treatment works.{{sfn |CAMS |2013 |p=15}} Major treatment works are located at Horwich on the upper river, at Wigan Wastewater Treatment works in Lathom on the lower section, and at [[Skelmersdale]] on the River Tawd.{{sfn |DMC |2014 |p=23}} Upgrades to the Wigan and Skelmersdale Treatment Works have been carried out, to improve the quality of the final effluent before discharge into the river system, while in Wigan, the sewage system has been improved, to reduce the amount of raw sewage discharged into the river by combined sewer overflows. In Standish, the pumping station at Chorley Road has been upgraded to reduce its impact on the river, while in Horwich, there was an ongoing scheme in 2014 in which volunteers walked the river to identify pollution points, which were then followed up by officers from the Environment Agency. Run-off of nutrients and other pollutants from agricultural land has also been addressed through the Catchment Sensitive Farming project, run jointly by [[Natural England]], the Environment Agency and the [[Department for Environment, Food and Rural Affairs]].{{sfn |DMC |2014 |p=23}} Another joint initiative between the Environment Agency and the [[Royal Society for the Protection of Birds]] has seen sea defences improved and {{convert|370|acre|ha}} of saltmarsh created as part of the Hesketh Outmarsh Coastal Realignment project.{{sfn |DMC |2014 |p=24}}