Corby Weir Investigation Project

Corby Weir Investigations and significant events

Background and History - Weir construction and Purpose

Concerns raised by fisheries interests - environmental impact on fish populations

EFP/SAP Workshops - discussions and evidence presented

Setting up of the Technical Working Group -> Corby Weir Investigation Project

Independent Consultant appointed - Peter Walker of APEM Ltd

Report on Options Appraisal

Final Consultation on Options with Fisheries Interests

Weir Construction

Built in 1996 to replace the weed and bridge affected site at Warwick Bridge, at a cost of approx £300,000.Corby Weir is a compound non-standard Crump weir design , not built to BS specification as it incorporates a 1 : 8 rather than 1 : 5 downstream slope for fish counter instrumentation purposes and to reduce water velocities over the weir to assist fish passage.The construction provides a static cross section and fixed bed to allow accurate monitoring of laminar flow.

Its principle purpose being to provide

Continuous Flow measurement and Flood forecasting

Fish count data to determine migratory fish populations and influence management decisions

Concerns raised by Fisheries interests

- Barrier to free movement of fish

- Predation of smaller fish particularly smolts above and below the weir

- Does the Fish Counter provide valuable data and how accurate is it ?

Workshop discussions and evidence

Short film and discussion points

Salmon stocks and rod catch

Fish counter validation and species apportionment

Nov 2012 what Options should we consider ?

Technical working group formed

First meeting Jan 14th - EA submissions of essential Hydrology requirements of CWThe Hydrology team stressed that CW is a critical component in providing continuous flow data that has to be maintained for Flood forecasting and Flood warning – for Carlisle and neighbouring districts developed on the Eden Flood Forecasting model which is updated at CW giving reliable flows up to extreme flood events. This data informs the County Flood response teams and emergency services. The weir is the only fixed structure of its kind on the Eden and gives extremely accurate data. The next upstream gauging stations being Temple Sowerby and Udford (Eamont).The site also serves several functions for Water Resources management providing data for the CAMS flow calculation, a low flow alarm site, a means of assessing effects of abstraction by UU of water upstream at Cumwhinton and groundwater together with discharges above the weir.

REDFA questioned whether less intrusive methods of flow measurement had been considered . Also whether the position of CW so close to Carlisle gave sufficient time warning of events. Additionally whether monitoring of severe flood events were reliable due to downstream backing up effects. REDFA stressed the need for a full and independent review of the Weir impacts on Fish Passage.

Corby Weir Investigation Project commissioned by the EA Independent Consultant brief agreed by partiesConsultant Peter Walker of APEM Ltd appointed

Site visit and second meeting Feb 14th

REDFA and YFF presented a prepared Position Statement setting out our contentions that- the Weir presents a major obstruction to fish passage with added predation mortality -the fish counter has not provided accurate count data or species apportionment - consent for construction of the Weir from YFF/CC was reached with NRA on the agreement that the fish counter would provide valuable data on the management of Salmonid populations

In conclusion we acknowledged that flow measurement in the vicinity of this site is essential for flood management and water resources purposes but that all options must be considered to reduce the unintended long term impact to our Fisheries and the rivers SAC designation.

This may be the only opportunity that we have to plan and bring about these improvements in the foreseeable future

Peter Walker of APEM Ltd to present a report on his findings and provide the Options Appraisal for Corby Weir at the next working group meeting.

Because of the technical complexities in assessing the Flow Management requirements this date has been scheduled for March 26th

Final consultation and discussions with Fisheries interests

Evening meeting to be arranged 1st or 2nd week April