Portmadoc Holiday Camp Limited, Aberdunant Caravan Park, Prenteg, Porthmadog, Gwynedd, LL49 9SR

Author: Charlotte Lillywhite, Senior Permitting Officer (Water Resources)
Application numbers: PAN-021527, PAN-021528, PAN-021531, PAN-021532, PAN-021533 & PAN-021534
Licence numbers: N/A
NRW Region: North West
Date of Application: 30/03/2023

Applicant details:  Portmadoc Holiday Camp Limited, Aberdunant Caravan Park, Prenteg, Porthmadog, Gwynedd, LL49 9SR

Summary of the proposal: The applicant has applied for three abstraction and three impoundment licences to facilitate a new Hydroelectric Power (HEP) scheme with three intakes as detailed below:

• Point A - on the Afon Mur-gwenyn at National Grid Reference (NGR) SH 58067 42097
• Point B - on an un-named tributary of the Afon Mur-gwenyn at NGR SH 58006 42074
• Point C - on an un-named tributary of the Afon Mur-gwenyn at NGR SH 57914 41924

A singular intake design has been proposed for the three intakes with the following maximum abstraction rates: 16 litres per second (l/s), 57.6 cubic metres per hour (m³/hour), 1,382.4 cubic metres per day (m³/day) and 504,576 cubic metres per year (m³/year); above a Hands off Flow (HoF) of 3l/s.  The applicant states the design aligns with NRW Hydropower Guidance for Zone 1 HEP schemes with a 40% take.  All proposed intakes include the following: 3 millimetre (mm) coanda intake screening, plunge pools with minimum water depth of 300mm, stepped fish easement, ramp for eel pass tiles and wing walls.

Water abstracted at each intake would be piped to a header tank at NGR SH 58070 42080 located downstream of Point A on the bank of the Afon Mur-gwenyn. The following design features are associated with the intake pipes for Points A, B and C, prior to them entering the header tank: manual ‘shut-off valves’, ‘removable flange plates for orifice inspection / maintenance’; and ‘in-line orifice plates’ (to limit the maximum abstraction rate from each intake). The header tank is designed to operate at 48l/s (based on the combined maximum abstraction rate of 16l/s at each intake) which is the turbine design flow. ‘One way flap valves’ are proposed on the intake pipes associated with Points A and B once they enter the header tank. No valve is proposed for Point C.

Once water abstracted from Points A, B and C fills the header tank, a penstock pipe would transport the water to the turbine. A discharge arrangement is proposed to dissipate any remaining energy, the discharge culvert includes a 40mm horizontal bar screen and abstracted water would be discharged to the Afon Mur-gwenyn at NGR SH 58938 41876.

Case history:  

Justification of requirements and water efficiency: NRW Hydropower Guidance for Zone 1 HEP schemes specify a maximum abstraction rate of 1.3 times Qmean flows to ensure high flow protection. NRW are satisfied with the abstraction rates proposed for Points A and B, however, NRW do not consider the quantities applied for at Point C to be appropriate as they are 1.7l/s more than permitted for a Zone 1 proposal, based on NRW flow estimates. As the header tank is integral to the proposed scheme, it is not possible to authorise Points A and B as an individual intakes, even though the proposed maximum abstraction rates are in line with guidance. All points of abstraction would need to align with guidance for the proposal to be considered acceptable. NRW also have maintenance / inspection concerns regarding the following: proposed orifice plates; and the header tank one way flap valve arrangement, as valve failure could result in cross catchment transfer of water. Although the efficiency of the proposal is considered reasonable, there are concerns with the abstraction quantities applied for at Point C. Therefore, NRW does not consider the quantities of water applied for to be fully justified or reasonable.

Water Framework Directive status and water availability: The detailed WFD assessment concluded that there is a risk of deterioration of the waterbody status of multiple waterbodies and that the project has potential to conflict with the multiple water body mitigation measures either now or in future.

Impact assessment of proposal: NRW do not consider the maximum abstraction rates applied for at Point C to be protective of high flows, or the HoF applied for at Point A to be protective of low flows, based on NRW flow estimates. Therefore the current proposal would reduce flows within the depleted reaches created downstream of Points A and C beyond those considered acceptable under NRW HEP Guidance. There are concerns around total length of rivers that would be impacted by reduced flows being greater than 15% for each watercourse, plus in combination / cumulative impacts from scheme alone. The reduced flows could impact on hydromorphology, water quality, biology and fish elements. Point C is considered to be open and unconfined and at risk of outflanking; the applicant proposed additional wing walls to  counteract this risk, which  does not align with NRW HEP guidance.

The above concerns regarding impacts on flow could impact on the following features present within the viscinity of the proposal:

• Ecology - Lesser horseshoe bat, western acidic oak and associated atlantic bryophyte communities, otter, rivers and streams.
• Fisheries - European eel, atlantic salmon and seatrout, brown trout, stickle backs, minnow, bull head and stone loach.

The proposal could result in impacts to water quality elements as follows: Any impacts to temperature are anticipated to be localised to the proposal, within the depleted reaches; whilst any impacts to water clarity from reduced sediment transport could impact the depleted reaches and downstream of the proposed discharge. Outstanding concerns regarding the risk of cross-catchment transfer of water could further impact on water quality.

NRW are satisfied with the following aspects of the proposal: the proposed design would secure a 40:60 flow split (to protect flow variability), eel-way ramp with eel pass tiles, stepped fish easement and  plunge pool (minimum depth 300mm), 3mm Coanda intake screen associated with each intake; and 40mm horizontal bar screen on the discharge culvert and proposed discharge arrangement.

NRW have been unable to rule out adverse effect on site integrity to Coedydd Derw a Safleoedd Ystlumod Meirion / Meirionnydd Oakwoods and Bat Sites Special Area of Conservation (SAC) or Pen Llyn a'r Sarnau / Lleyn Peninsula and the Sarnau SAC.

NRW consider the proposal likely to damage the Aberdunant Site of Special Scientific Interest (SSSI) and Glaslyn SSSI.

Statutory Consultation: Statutory external consultation and notification sent to Snowdonia National Park Authority and Dŵr Cymru Welsh Water respectively on 04/07/2023.

External Representations: In accordance with Water Resources Act 1991 (as amended by the Water Act 2003), the application was advertised in The Cambrian News on 12/07/2023 and on the NRW website. No representations were received regarding the applications.

Protected Rights: No protected rights were identified as being at risk of derogation as a result of the variation. No lawful users were identified as being at risk of being impacted as a result of the variation.

Costs/ Benefits:

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: No adverse effects upon the social and economic well being of local communities in the rural area are perceived as a result of this proposal.

Sustainable Management of Natural Resources: We are satisfied that this decision is compatible with our general purpose of pursuing the sustainable management of natural resources in relation to Wales and applying the principles of sustainable management of natural resources.

Conclusion and recommendation: NRW recommendation recommend refusal of the applications for the following reasons:-

• NRW do not consider the proposal to be in line with NRW HEP Guidance flow standards which are designed to protect the environment at low and high flows, meaning, the proposal would impact on ecology, fisheries and water quality.
• NRW have been unable to rule out adverse effect on site integrity to Coedydd Derw a Safleoedd Ystlumod Meirion / Meirionnydd Oakwoods and Bat Sites SAC or Pen Llyn a'r Sarnau / Lleyn Peninsula and the Sarnau SAC.
• NRW consider the proposal likely to damage the Aberdunant SSSI and Glaslyn SSSI.
• NRW have been unable to rule out risk of deterioration of WFD waterbody status / prevention of meeting the WFD objectives of multiple waterbodies.

Contact the Permitting team responsible for this decision:

Email: permittingconsultations@naturalresourceswales.gov.uk

Or write to:

Water Resources Team Leader
Permitting Service
Natural Resources Wales
Welsh Government Offices
King Edward VII Avenue
Cardiff
CF10 3NQ