The power will come in two large bursts which the national grid will have trouble distributing. It can coincide with a period where little extra power is needed such as during the night.
There are several endangered, rare species of fish which currently migrate into the Severn estuary and river notably shad, lamprey, Atlantic salmon, and seatrout.
There are thousands of migrating birds which use the estuary for overwintering and breeding grounds, among these shell duck, redshanks, and many species of geese and waders.
Water quality and feeding grounds
There will be changes to currents which will affect water turbidity and sedimentation leading to detrimental effects to plankton, and erosion of salt marshes, mudflats, and sandflats.
From the above environmental concerns, the tidal barrage would seem to…