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WPCC1633 (Abstraction) and WPCC1634 (Impoundment)

Water Resources Decision Statement for proposed hydro-electric power scheme on the Afon Clywedog


Water Resources Decision Statement for proposed hydro-electric power scheme on the Afon Clywedog

In this document, Natural Resources Wales (‘NRW’) means the Natural Resources Body for Wales (‘the Body’) established by Article 3 of the Natural Resources Body for Wales (Establishment) Order 2012.

Please note that on 01 April 2013,  the functions previously conducted by the Countryside Council for Wales (‘CCW’), Forestry Commission Wales (‘FCW’), and the  functions of the Environment Agency within Wales (‘EA/EAW’), (CCW,FCW and EA/EAW together ‘the Legacy Bodies’) were transferred to NRW.

In determining this application, NRW has exercised its duties and powers under the Water Resources Act 1991 (as amended) and the Environment Act 1995 and has taken account of guidance issued by the Legacy Bodies where relevant.

NRW have decided to refuse the licence applications.

Application numbers: WPCC1633 (Abstraction) and WPCC1634 (Impoundment) 

NRW Area: North

Date of Application: 13/03/2014

Applicant details: Derwent Hydroelectric Power Limited

Summary of the proposal: The applicant has applied to install and operate a new hydropower scheme on the Afon Clywedog at Brithdir, Dolgellau, Gwynedd. The scheme will consist of a new concrete intake structure (at the abstraction point), a gravity feed pipe, a power house (not considered for the abstraction and impounding licences, but required as part of the scheme to operate), tailrace and outfall structure. The applicant originally applied for 100 percent abstraction above a Q85 residual flow up to a maximum instantaneous rate of 630 litres per second (l/s). During the determination of the application the applicant revised this to a 40% abstraction above a Q95 residual flow up to a maximum instantaneous rate of 630 l/s.

All proposed abstracted water would be returned to the Afon Clywedog at National Grid Reference (NGR) SH 74929 18816, approximately 1.9 kilometers downstream of the abstraction point.
Source of Supply: Inland water (river) known as Afon Clywedog at Brithdir, Dolgellau, Gwynedd.
Points of abstraction and quantities:  At National Grid Reference SH 76163 17800.

54,432 cubic metres per day
19,867,680 cubic metres per year
At an instantaneous rate not exceeding 630 litres per second.
Means of abstraction: Intake works and a gravity feed pipe.
Purpose of abstraction: Power production.

Abstraction period: All year.

Case history:  




Application received and accepted as valid but supporting information requested.


Supporting information for Habitats assessments received.


Application allocated to Permitting Officer.

08/08/2014 – 14/08/2014

Internal and external consultation sent out.


Application advertised.

01/09/2014 – 24/11/2014

Representations received and copies subsequently requested by the applicant. Copies released following notice period where representors could object to their representation being released.


Appendix 4 and Appendix 11 sent for consultation. Appendix 23 sent to local authority to request details for the in-combination assessment. Responses received on 20/01/2015.


NRW provided the applicant full details of our concerns regarding the proposal.


Applicant submitted additional information.


NRW provided the applicant a full response detailing processes and outstanding concerns. The applicant was given until 15/06/2015 to provide any additional information they wished to be considered in the Appropriate Assessment.


The applicant provided a revised intake design and confirmed they would accept an abstraction regime of 40 percent abstraction above a Q95 residual flow up to the maximum instantaneous rate. The email also challenged NRW’s interpretation of legislative requirements regarding the Habitats Regulations Assessment, the interpretation of ‘likely’ and ‘significant’ and the need for an Appropriate Assessment.

15/06/2015 – decision date

Completion of Appropriate Assessment and relevant decision documents.

Justification of quantities: The turbine design flow of 630 litres/second represents ~58 percent of the average daily flow (Qmean) estimate (1082 litres/second) and is therefore in accordance with the Environment Agency’s Hydropower Good Practice Guidelines ([GPG] policy relevant during determination of this application) which recommends that maximum abstraction should not exceed Qmean.  The Q95 residual flow from the revised proposal is 144 l/s.

The proposed annual quantity is equivalent to 365 times the maximum daily quantity proposed which is not in accordance with the GPG which recommends a maximum of 220 days per year. However, in line with new guidance, 365 days would be acceptable.

The applicant has been unable to confirm the net head for the proposed scheme as an intake arrangement has not been agreed. However, the applicant has advised that they estimate the proposed scheme to be 500 kW project, or a little under. Given that the head difference is unknown, NRW are not able to estimate the efficiency and power output of the scheme. 

Resource assessment: The Catchment Abstraction Management Strategy (CAMS) resources assessment status for this area is ‘water available’. Current CAMS policy is to determine all water abstraction licences in accordance with statutory requirements, national and local policy. Licence applications will be considered on a case-by-case basis but the following general principles apply to all licences:

  • Time limits will apply to all new and varied licences
  • Time limit to 31/03/2030

The proposal is non-consumptive, therefore no impacts towards the overall CAMS resources status are anticipated as a result of this proposal.

Impact assessment of proposal: NRW objected to the abstraction regime originally proposed which was a 100 percent abstraction above a Q85 residual flow up to the maximum instantaneous rate. Even with the increased residual flow of Q85, a 100% abstraction is not acceptable as it would result in significant flat lining of the flow in the depleted reach. The depleted reach has good runs of migratory salmon and sea trout within it up to NGR SH 75390 18704 for salmon and NGR SH 75670 18508 for sea trout. Given this, the applicant was advised that, purely from a fisheries perspective and in line with the guidance relevant to the determination of this application, the maximum abstraction that would be considered acceptable is a 40% abstraction above a Q95 residual flow up to the maximum instantaneous rate. The applicant advised that they accepted this abstraction regime on 15/06/2015. Migratory salmon and sea trout can access the depleted reach up to the NGRs specified above. There are impassable falls located at NGR SH 76118 17880 so migratory fish are unable to access the depleted reach above this point. However, there are resident brown trout located above the impassable falls, therefore NRW would require a suitable fish pass to be constructed if any abstraction was approved at this location, to allow resident brown trout to migrate past the intake structure and ensure connectivity is maintained within the river above the impassable falls. Any design would need to be approved by NRW prior to construction. 

However, significant concerns were raised regarding impacts on the ecology within the depleted reach and therefore an Appropriate Assessment was undertaken regarding impacts on the Special Area of Conservation (SAC) features. See Conservation section below.
Statutory Consultation: Snowdonia National Park were consulted and responded expressing the following concerns regarding the proposal:

  • Concerns regarding location within SAC, SSSI and Woodland which is covered by a Tree Preservation Order (TPO)
  • Concerns regarding pipeline route running alongside Torrent Walk which is one of the most utilised walkways in the National Park
  • Concerns regarding impacts on flow of the waterfall meaning the authority is likely to object to the scheme
  • Concerns that part of the pipeline route would be within woodland covered by TPO and is likely to have an effect in terms of tree felling. Loss of trees may also have an adverse effect on bryophytes, as well as potentially causing further instability within the woodland and lead to greater loss of trees. The proposed pipeline route is likely to have an adverse effect on rooting structures of trees elsewhere within the woodland, particularly if it is proposed to underground the pipe within the woodland. In the event of the pipeline being placed above ground level, the Authority is likely to oppose such a scheme if it is exposed to public vantage points
  • Concerns that, should NRW issue licences to abstract and impound water, this will lead to the applicant wanting to fell trees within the SAC, SSSI and TPO area. This could also affect humidity within the gorge and should be considered as an ‘in combination’ effect for the purposes for satisfying Regulation 61 of the Conservation if Habitats and Species Regulations 2010

Concerns relating to construction, the pipeline route and turbine house are considered issues relating to the planning permission. Concerns relating to designated sites have been address, see Conservation section below.
External Representations: The proposal was advertised in the Cambrian News on 20 August 2014. 4 responses of representation were received with regard to the application. The following concerns were raised.

Issued raised by representation(s)

NRW response

1)    Impacts on Special Area of Conservation (SAC), Site of Special Scientific Interest (SSSI) (including the bryophytes in humid areas) and Mawddach Woodlands Reserve.

During determination of the applications, NRW has completed assessments regarding the potential impact on the Meirionnydd Oakwoods and Bat Sites SAC and Coedydd Dyffryn Wnion SSSI.


As a result of the assessment of impact on the SAC (which include the features of the SSSI) NRW has been unable to conclude that the proposal will not adversely affect the integrity of the Meirionnydd Oakwoods and Bat Sites SAC (and SSSI) and therefore we are not able to issue the licences applied for. As such, the applications are being refused.



2)    A Habitats Regulation Assessment (HRA) needs to be completed. Where a HRA is required, an Environmental Impact Assessment (EIA) also needs to be completed.


As stated above, NRW has assessed the proposal under the Habitats Regulations which has resulted in the applications being refused.


With regards to the need for an EIA:

In accordance with the legislation, if a scheme requires planning permission, EIA will be a planning matter rather than a permitting matter. In this case, planning permission will be required for the proposed development therefore the requirement for an EIA falls under the planning permission (dealt with by the Local Planning Authority) and is not required by NRW to determine these applications. 


3)    Impact on amenity value of the waterfalls at Torrent Walk.


During determination of the application NRW advised the applicant that a Flow Survey would be required to enable us and the Planning Authority to assess the visual impact on flows at Torrent Walk as a result of the proposal and agree suitable mitigation if required. However, during determination of the application it became apparent that the concerns relating to impacts on the SAC, see point 1) above, were likely to override this concern and NRW advised the applicant to await the outcome of the Habitats Regulations Appropriate Assessment before proceeding with the Flow Survey.


Given the outcome of the Habitats Regulation Appropriate Assessment, the applications are being refused by NRW therefore there is no requirement for a Flow Survey to be completed.


4)    Visual impacts on surrounding area due to pipeline and generating equipment.


The visual impacts of the pipeline, turbine and associated infrastructure are considered a matter for the Planning Authority to consider.

5)    Impacts on tourism and local business.


No specific details were provided for NRW to consider impacts on businesses or tourism in the area. However,the applications are being refused, so this matter has not been pursued.


6)    In combination impacts on species eg Dormice and Bats following work to widen the A470 near Birthdir.


NRW considers impacts on Dormice and Bats are more likely to be as a result of construction of any scheme and these are therefore consider an issue for the Planning Authority. However, due to concerns regarding impacts on the SAC, see point 1) above, no abstraction or impoundment licences will be issued as a result of this application.

Protected Rights: No protected rights or lawful users have been identified as being at risk of derogation as a result of this proposal.

Conservation Issues: An assessment under the CRoW Act has been completed for the Coedydd Dyffryn Wnion Site of Special Scientific Interest (SSSI). The SSSI comprises of multiple features including mosses, liverworts and slime moulds that require high humidity and our found within the proposed depleted reach. The assessment was sent for consultation on 02/12/2014 and the Designated Conservation Officer (DCO) responded on 19/12/2014 confirming their agreement with the outcomes of the assessment and advised that the proposal should not go ahead.
An Appendix 11 assessment under the Habitats Regulations was completed for the Meirionnydd Oakwoods and Bat Sites SAC and sent for consultation. As a result of consultation with the DCO, it has been confirmed that the proposal is likely to have a significant effect upon the Meirionnydd Oakwoods and Bat Sites SAC. An Appropriate Assessment has therefore been completed by Natural Resources Wales as the relevant competent authority.
The SAC feature of concern is the Dry Woodland and scrub (Old oak woods with llex and Blechnum in the British Isles, Tilo-Acerion ravine woodlands (Priority Feature)). These habitats are a primary reason for the selection of the Meironnydd Oakwoods and Bats Sites SAC which is a very large example of old sessile oak woods in north Wales, with an outstanding Atlantic flora of bryophytes (mosses and liverworts).

The objective is for the Woodland SAC feature to be in a favourable conservation status, where the following conditions (Conservation Objectives) are satisfied:-

  • The total extent of the woodland area, including woodland canopy and scrub, woodland glades and associated dry heath, bracken and grassland shall be maintained as indicated on maps, see Annex 2 in the Core Management Plan (2008), some 2.813.02  hectares (ha) in total
  • The abundance and distribution of common and typical ferns, (Atlantic, sub-Atlantic, western and oceanic) mosses and liverworts, lichens (and slime moulds), will be maintained and increased. Refer to indicative lists in Table 3 in the Core Management Plan (2008)
  • The abundance and distribution of uncommon mosses and liverworts, lichens and slime moulds, will be maintained or increased. Refer to indicative list in Annex 3 Table 6 in the Core Management Plan (2008)

The Appropriate Assessment has been carried out taking into account the above conservation objectives. Of particular concern are the common and localised moss and liverwort species and uncommon and localised moss and liverwort species with a distribution along the north western side of the British Isles, known as oceanic species. These oceanic species require an oceanic climate (one with warm, but not hot summers and cool, but not cold winters and with a relatively narrow annual temperature range and high rainfall).

A number of the oceanic species found in Torrent Walk, located within the depleted reach, are desiccation-sensitive and require high levels of humidity or they cannot survive.

When considering the potential impacts on the SAC as a result of the proposal and having had regard to the mitigation measures proposed by the applicant, NRW cannot conclude that no adverse effect will be caused by the scheme. The information submitted does not show sufficient evidence or understanding to conclude that reduced river levels (as a result of the proposed HEP scheme) would not reduce relative humidity in the gorge to an extent that would have a detrimental effect on the bryophytes that play a key role in identifying the Old Sessile Oakwood habitat for which the SAC has been selected, and form part of the conservation objectives. Therefore reducing the abstraction to 40 percent above Q95 as mitigation does not enable us to conclude that no adverse effect on the SAC feature will be caused.

When considering potential impacts of the proposal ‘in-combination’ with other plans, permissions or projects NRW has concluded that the proposed abstraction, which ‘alone’ could result in reductions in humidity, could also act in combination with the creation of additional tree canopy gaps, due to any tree felling necessary for the installation of the pipeline([which would be subject to planning permission), to increase the potential for humidity reduction at some key bryophyte locations.

As a result of the outcomes of the assessment, NRW cannot conclude, beyond reasonable scientific doubt, that the proposal will not adversely affect the integrity of the Meirionnydd Oakwoods and Bat Sites SAC and therefore the applications must be refused.

Costs/ Benefits:

NRW will incur the cost of determining the application.

In determining the applications in accordance with local and national policy, NRW is fulfilling its duties as a regulator.

Biodiversity and sustainable development: Significant concerns have been raised regarding impacts on biodiversity which NRW have been unable to address therefore the proposal is not considered sustainable.
Social and Economic welfare of rural communities: Respondents to the application indicated that they considered there to be a risk to the economic and social wellbeing of the rural community because any scheme in this location would impact on the amenity value of the waterfalls at Torrent Walk, location within Snowdonia National Park and therefore subsequently impact on tourism and local businesses. No supporting information was submitted.
Conclusion and recommendation: Full and due consideration has been given to any representations made, and due regard has been taken of protected rights and other lawful users.

Following completion of an Appropriate Assessment, NRW are not satisfied that the supporting information provided by the applicant is sufficient to demonstrate that there will be no adverse impact on the integrity of the Meironnydd Oakwoods and Bats sites Special Area of Conservation.

NRW therefore recommended refusal of the applications (as modified).
Contact the Natural Resources Wales team responsible for this decision:

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