Analysis of information sources in references of the Wikipedia article "Severn Estuary" in English language version.
The Bristol Channel and Severn Estuary (the two entities cannot be separated physically or ecologically)
51.4617° N, 2.9965° W Severn Estuary, Coordinates
There is no defined boundary between the Severn Estuary and the Bristol Channel. The Welsh 'Mor Hafren' or 'The Severn Sea' includes the relatively enclosed waters to the line of the proposed barrage extending from Brean Down via Steep Holm and Flat Holm to Lavernock Point.