Table 4

NOTE: Re D, Sea-mammal survival: TPPs should be designed and operated to keep sea mammals away from the hydraulic turbines. This applies equally to both Linked-Bs and Type Z and therefore does not affect a comparison between them.
DE = double-effect, SE = single effect, HB = high-basins LB = low-basin, Linked-Bs = linked-basins

Environmental effects A B C E F
Type of TPP Linked-basins, SE, Fundy Sites A6(HB) and A8(LB) Single basin, DE, at Fundy Site A8
Mean, natural tidal range 10.0 m 10.0 m
Mean tidal range within HIGH basin as % of natural tide 34 % 68 % Z Z Z
Mean tidal range within LOW basin as % of natural tide 36 % 68 % Z Z Z Z
Mean water level within HIGH basin, compared to natural conditions +2.9 m 0.12 m Z Z
Mean water level within LOW basin. compared to natural conditions -2.6 m -0.12 M Z X
Number of passes through turbines, for a fish going in-and-out of TPP 1 2 Linked-Bs
Plant operation at or close to the rhythm of the natural tide no yes Z
Maximum head across turbines 6.96m 4.62m Z
Maximum water velocities through turbines 15.6m/sec 11.9m/sec Z
Stagnant flow within high basin % of the time 42% 18% Z
Stagnant flow with low basin % of the time 42% 18% Z
Simplicity of flow patterns See Fig 5 Z
Total scores for Linked Bs, SE-TPP 0 0 1 1 0
Total scores for Type Z (DE) plant 5 4 2 1 3