Water resources

Summary of supply sources

We obtain our water resources from three sources: Blithfield Reservoir, the River Severn and groundwater from 25 sites across our supply area. Approximately 40% of the total water available to us is taken from groundwater sources and the remaining 60% from the two surface water sources.

Groundwater is abstracted from over 60 boreholes (2-3 per source), all of which allow water to be pumped from the Triassic Sandstone aquifer. This aquifer is very porous (like a sponge) which means that it can hold large quantities of water in between the sand grains and in cracks in the rock. As the sandstone can hold large volumes of water the water levels within the sandstone do not fall very far in dry periods. This makes the groundwater sources a very reliable supply of water.

Blithfield Reservoir is an impoundment reservoir with a capacity of approximately 18.224 billion litres of water. It was formed in 1953 by the construction of a dam across the River Blithe. The raw water is taken out of the reservoir by pipeline to the treatment works at Seedy Mill near Lichfield before going into the distribution network. (For further information on Blithfield reservoir, its construction and history, visit our Blithfield Website.)

The River Severn is a regulated river i.e. flows in the river are augmented by inputs from both groundwater and reservoirs at its head at times of low flows. The regulation of the River Severn is controlled and operated by the Environment Agency who monitor and report on the situation regularly. We take water from the River Severn at Hampton Loade where it is stored in Chelmarsh Reservoir before being treated and distributed.

Current water resources position at 1st Jan 2013

Long term rainfall patterns for the period April to December 2012 were 156% of the ten year average. The rainfall for December 2012 has been over 200% of the ten year average at the end of an exceptionally wet year. Flows on the River Trent are currently high in response to the rainfall. The period of river regulation on the River Severn ceased in September, although, due to the heavy rainfall no releases were made over the year. Clywedog Reservoir in Wales is almost full and therefore in a healthy position for the next year. There are no groundwater resources issues. Blithfield Reservoir storage level was 100% on 1st January, 2013 and has been unusually high and spilling for much of the year. The overall water resources position is robust, however we will be keeping a watchful eye on the position over the spring and summer in case prolonged dry weather returns.

Reservoir levels

We use the level in Blithfield Reservoir as the main indicator of resource availability. Regular analyses of refill scenarios for Blithfield Reservoir are routinely carried out and the levels are monitored continuously.

Blithfield Reservoir water levels have been unusually high over the summer and autumn due to the heavy rainfall and it remains full.

River Severn

Clywedog Reservoir has not been used by the Environment Agency to release water into the River Severn to support river flows since October 2011. Reservoir storage at the end of December was almost full which is normal for the time of year. We are not currently in the regulation season.

Groundwater

Groundwater levels in the Sherwood Sandstone aquifer do not tend to react rapidly to short periods of high or low rainfall. Current groundwater levels are still lower than normal but recovering. Nevertheless, in general the reliable yield of our groundwater sources is unaffected by groundwater levels, and therefore we do not use groundwater levels as a means of assessing the water resources situation.

Rainfall

The rainfall (recorded at our Seedy Mill treatment works) for December was 206% of the ten year average figure.

Downloads

Adaptation report