Skip to main content


Title: Impact assessment of scour valve test at Roadford Reservoir on water quality of the River Lyd
Author: P. Rose
Document Type: Monograph
Annotation: EA additional title info: FWI/92/004
South West Water Services Ltd. released water from Roadford Reservoir on 21 October 1991 to test the operation of the scour valves for dam safety purposes. Flow at Lifton Bridge increased from 2.6 cumecs to a maximum flow of 8.5 cumecs over a period of 3 hours. Hourly samples were collected at Lifton Bridge on the River Lyd to assess the impact of the release on water quality. Suspended solids and particulate metal concentrations were found to increase as river flow increased. Relevant Environmental Quality Standards for concentrations of total zinc, total iron and suspended solids were exceeded at peak flow. The cause was considered to be the re-suspension of solids from the river bed. The solids may have been recently deposited during reservoir operation. Alternatively the source of metalliferous solids could be a legacy of the reservoir construction when there was disturbance of mineralised deposits and soils.
Publisher: National Rivers Authority
Publication Date: 1992
Publication Place: Exeter
Subject Keywords: RiversWater reservoirsWater levelsEnvironmental impact assessmentWater qualitySedimentsMetals
Geographic Keywords: EA South WestTamar catchment
Extent: 4; + appendices
Total file downloads: 279

Download PDF    Display PDF in separate tab