Water Cycle Study - East Devon District Council

Exeter and East Devon Water Cycle Study
plans for meeting future demand over a 25 year period are set out in the WRP, detailed design of
schemes is not undertaken until works have been granted funding by Ofwat.
7.4.2 Although not previously compulsory, companies have prepared 25 year water resource
management plans on a voluntary basis, and shared these with the Government and regulators,
since 1999. On 1st April 2007 these plans became compulsory under changes to the Water
Industry Act 1991, and this year for the first time they are also subject to public consultation
before they are finalised.
7.4.3 SWW’s Water Resources Plan is currently being finalised following consultation responses,
including from the EA and Defra. This study has used the second draft of the WRP, which is the
most comprehensive and up-to-date available. The information remains subject to change pending
the publication of the final plan in November 2009, however SWW have commented that the final
plan will not feature any significant changes from the 2 nd Draft.
7.5 Strategic water supply
7.5.1 The study area is located within SWW’s Wimbleball Strategic Supply Area (SSA), which stretches
from Tiverton in the north to Exmouth in the south and from Crediton in the west to Axminster
in the east. Drinking water supply is sourced predominantly from abstractions on the River Exe at
Allers Water Treatment Works (WTW) near Tiverton and Pynes WTW at Exeter. Abstraction of
natural flow from the River Exe is supported by augmentation releases from Wimbleball reservoir
located in Somerset. Wessex Water Ltd (the adjacent water supply company to the east) uses
Wimbleball reservoir for direct water supplies. There are no major storage reservoirs located
within the core study area.
7.5.2 The Wimbleball SSA is also dependent upon the significant groundwater resources of East Devon.
The Triassic Sandstone Group of the southern part of the Otter valley is the most significant in
terms of public water supply, with groups of boreholes being the typical method of abstraction.
SWW renewed abstraction licenses for a number of the key Otter Valley boreholes in 2000 and
the company’s WRP assumes that these licences will be renewed again in 2010.
7.5.3 SWW’s strategy for the Wimbleball SSA is to optimise East Devon groundwater abstractions to
serve the eastern fringes of the catchment in order to minimise the need to pump treated water
long distances from the Exe abstraction points. The Environment Agency has noted in it’s
representation on SWW’s 1 st Draft WRP that the water company had not considered the nonrenewal
of time limited abstraction licences in the Otter catchment, which could result in loss of
baseline deployable output in the Wimbleball SSA. The EA notes that SWW will need to take
further action to better understand the environmental impacts of their abstractions in order to
support the licence renewal process. Although the EA’s guidelines for water resources planning
state that time limited licences should not pose a risk to security of supply, it is important to note
that the Otter surface water body is identified as being ‘’probably at risk’ from abstraction by the
Environment Agency’s Water Resources Strategy [EA 2009] and as currently having poor
ecological status in the draft River Basin Management Plan for the South West [EA 2008d].
7.6 Water demand forecasts
7.6.1 South West Water’s 2 nd draft Water Resources Plan (WRP) predicts an overall fall in demand until
about 2017/2018, after which demand is expected to rise. SWW’s Total Demand forecast for the
69 Ref EWCS April 2010