these should have been dug over the last 40+ years when I believe the last reservoir in Yorkshire was actually built.
Grimwith Reservoir completed in 1983, not far from the larger and much older Upper Nidderdale and Washburn Valley reservoirs. The last built in the UK overall was in 1992: Carsington Water in Derbyshire, and there’s one under construction in Hampshire due to be finished around 2030: Havant Thicket reservoir, which is intended to reduce demand on the famous chalk streams in the area.
Grimwith was one of several commissioned and built in response to the notorious 1976 drought.
Such ‘get on with it and build’ thinking is what’s needed now. The UK economy was hardly flourishing during the late ’70s but the money was found.