Editing River Derwent, Derbyshire (section)

==River uses==
{{Infobox UK legislation
| short_title           = Derwent Navigation Act 1719
| type                  = Act
| parliament            = Parliament of Great Britain
| long_title            = An Act for making the River Darwent, in the County of Derby, navigable.
| year                  = 1720
| citation              = [[6 Geo. 1]]. c. 27
| introduced_commons    = 
| introduced_lords      = 
| territorial_extent    = 
| royal_assent          = 7 April 1720
| commencement          = 
| expiry_date           = 
| repeal_date           = 
| amends                = 
| replaces              = 
| amendments            = 
| repealing_legislation = 
| related_legislation   = 
| status                = 
| legislation_history   = 
| theyworkforyou        = 
| millbankhansard       = 
| original_text         = 
| revised_text          = 
| use_new_UK-LEG        = 
| UK-LEG_title          = 
| collapsed             = yes
}}
The lower river from Derwent Mouth upstream as far as [[Derby]] was made navigable under an [[act of Parliament]] of 1720, the '''{{visible anchor|Derwent Navigation Act 1719}}''' ([[6 Geo. 1]]. c. 27), and this stretch opened to navigation in 1721. Traffic ceased about 1795 and the navigation was acquired by the owners of the competing [[Derby Canal]]. The river is no longer considered navigable, although the upper river is widely used by kayakers and [[Canoeing|canoeists]] who enjoy the fast-flowing water and the slalom course at [[Matlock Bath]].<ref>{{cite web | url = http://www.jim-shead.com/waterways/localww.php?cy=Derbyshire | title = Waterways of Derbyshire | publisher = Jim Shead | access-date = 6 June 2009}}</ref><ref>{{cite web | url = http://www.canoeslalom.co.uk/courses/matlock.htm | title = Matlock Canoe Club | publisher = Slalom UK | access-date = 7 July 2009}}</ref>

The river was also used to power the many textile mills that were built along the Derwent between Matlock Bath and Derby. Initially, the need for water power was quite modest, for example [[Lombe's Mill|Lombe's Silk Mill]] in Derby, which is considered to be the forerunner of the later [[cotton mill]]s, only needed to use the power provided by a small mill stream, and [[Richard Arkwright]]'s [[Cromford Mill]], the world's first water-powered cotton spinning mill, only used a small tributary of the Derwent in conjunction with a lead mine [[sough]].<ref name="dvm">{{cite web|url=http://www.derwentvalleymills.org/history/history-and-development/96-why-the-derwent-valley|title=Why the Derwent Valley|publisher=Derwent Valley Mills – World Heritage Site|access-date=28 February 2013|url-status=dead|archive-url=https://archive.today/20120524174208/http://www.derwentvalleymills.org/history/history-and-development/96-why-the-derwent-valley|archive-date=24 May 2012}}</ref> The later mills at [[Belper North Mill|Belper]], [[Darley Abbey]] and [[Masson Mill]] were much larger and needed to harness the full power of the river to drive their complex machinery. This required the construction of large [[weir]]s across the Derwent that still remain as significant features in the riverscape.<ref name="dvm2">{{cite web|url =http://www.derwentvalleymills.org/history/key-sites|title=Key Sites|publisher=Derwent Valley Mills – World Heritage Site |access-date=28 February 2013}}</ref>

These sites were all important in the development of the [[Industrial Revolution]], and Arkwright's innovation, along with several local competitors, is recognised today by the designation of the area as the [[Derwent Valley Mills|Derwent Valley Mills World Heritage Site]].<ref>{{cite web| url = http://www.arkwrightsociety.org.uk/| title = The Arkwright Society| publisher = The Arkwright Society| access-date = 1 December 2011| url-status = dead| archive-url = https://archive.today/20120730152428/http://www.arkwrightsociety.org.uk/| archive-date = 30 July 2012}}</ref>

The power of the Derwent is still harnessed at a number of these historic mill sites, producing [[hydro-electricity]] from turbines instead of driving mill wheels, with a recent development being the construction of a hydro-electric station at Longbridge weir, adjacent to the Riverside Gardens in Derby.<ref name="lbw">{{cite web|url=http://eplanning.derby.gov.uk/acolnet/DocumentsOnline/documents/24094_15.pdf|title=Longbridge weir Hydro Project. Environmental Report|publisher=Derby City Council|access-date=28 February 2013|url-status=dead|archive-url=https://web.archive.org/web/20131005122236/https://eplanning.derby.gov.uk/acolnet/DocumentsOnline/documents/24094_15.pdf|archive-date=5 October 2013}}</ref>

[[Howden Reservoir|Howden]] and [[Derwent Reservoir, Derbyshire|Derwent Reservoirs]] in the upper valley were both completed in 1916 to supply the cities of [[Sheffield]], [[Nottingham]], Derby, and [[Leicester]]. The adjacent [[Ladybower Reservoir]] was completed in 1945 to cover increasing demand.  Treated water from these reservoirs flows down the {{convert|28|mi|adj=on}} Derwent Valley Aqueduct parallel to the river. The river also indirectly supplies [[Carsington Reservoir]], with the water taken from the river by a pumping station at [[Ambergate]] in times of high flow. When flows are low, water is released back into the river via the same {{convert|6.5|mi|adj=on}} route of tunnels and aqueducts, thus allowing greater abstraction rates downstream at [[Little Eaton]] in the drier summer months. Today all these reservoirs are managed by [[Severn Trent|Severn Trent Water]].<ref>{{cite web | url = http://www.moretoexperience.co.uk/server.php?show=nav.6108 | title = Upper Derwent Valley – Facts and Figures | publisher = [[Severn Trent Water]] | access-date = 6 October 2008}}</ref><ref>{{cite web | url = http://www.moretoexperience.co.uk/server.php?show=nav.6019 | title = Carsington Water – Facts and Figures | publisher = [[Severn Trent Water]] | access-date = 6 October 2008}}</ref>

The valley of the Derwent provides an important communications route. Between Derby and [[Rowsley]] the valley is followed by the [[A6 road (England)|A6 road]], which was the main road from London to [[Manchester]] until the creation of the motorway network, and is still a busy single-carriageway road. The former [[Midland Railway]]'s lines from Derby to Sheffield and Manchester also followed the Derwent, the former as far as Ambergate and the latter as far as Rowsley. The Sheffield line still operates as part of the [[Midland Main Line]], but the Manchester line was severed north of Matlock in 1968, and the section from Ambergate to Matlock now forms the [[Derwent Valley Line]], a single-track branch line. Between Ambergate and Cromford, the river, road and railway are also paralleled by the [[Cromford Canal]]. The terminus was once connected to Manchester across the [[High Peak Trail|High Peak]] by the early [[Cromford and High Peak Railway]].<ref name=phil/><ref>{{cite book | last = Rimmer | first = A. | year = 1998 | title = The Cromford & High Peak Railway | edition = New | id = Locomotion Papers No. 10 | publisher = Oakwood Press | isbn = 0-85361-319-2}}</ref>