The Environment Agency now accepts – in its "statement for the planning committee" of 13 August 2021, released after an FOI request – that changes to the unsaturated zone from Aggregate Industries' scheme to quarry Straitgate Farm would affect stream flows:
In our view, the main risk of any increase in unsaturated zone flow rates resulting from the reduction in unsaturated zone thickness would be to the headwaters of the streams whose catchments are partly in the proposed quarry area (Pitt Copse Stream, Birdcage Stream, Straitgate Spring, Cadhay Spring, Cadhay Wood Stream, Straitgate Farm Spring, Cadhay Bog Stream)…
Never mind, says the Environment Agency:
...the arguments on headwaters presented above relate only to the timing of recharge.
In May 2019, Professor Brassington wrote:
If the proposed quarry increases runoff and reduces groundwater recharge, then the flows of both the Cadhay Wood Stream and the Cadhay Bog Stream will reduce as well as the various springs that flow into these woodlands. This will have a detrimental impact on the viability of the ecosystems that is expected to be permanent.
In October 2019, Professor Brassington also wrote:
Wood describe the fact that removal of most of the unsaturated zone will result in flashier groundwater baseflows to the springs…. The streams that flow from the springs also support local habitats especially Cadhay Wood and Cadhay Bog.
This has implications for downstream riparian owners, who have legal rights under common law:
A riparian owner is anyone who owns a property where there is a watercourse within or adjacent to the boundaries of their property and a watercourse includes a river, stream or ditch.
In recognising the change in stream flows – whether "only to the timing of recharge" or otherwise – the Environment Agency is endorsing a scheme that imposes unlawful changes upon downstream riparian owners, riparian owners who have the legal right to receive a flow of water in its natural state, without undue interference in quality or quantity.
The Environment Agency helpfully sets out the rights of riparian owners:
Water should flow onto or under your land in its natural quantity and quality. This means that water should not be taken out of a watercourse if it could lead to a lack of water for those who need it downstream.
This is based on case law, Chasemore v Richards [1859] 7 HL 349 29 LJ Ex 81.
He has the right to have it come to him in its natural state, in flow, quantity, and quality, and to go from him without obstruction;
It would obviously be unlawful for Devon County Council to permit any scheme knowing that by doing so would result in unlawful impacts to third parties.
