) ▁of ▁water . ▁ ▁When ▁the ▁tunnel ▁is ▁open , ▁the ▁lake ' s ▁tur bid ity ▁increases . ▁The ▁sudden ▁infl ux ▁of ▁the ▁Ad ige ' s ▁water , ▁which ▁is ▁both ▁appreci ably ▁col der ▁and ▁more ▁poll uted ▁than ▁the ▁lake ' s , ▁causes ▁a ▁considerable ▁heat ▁shock ▁and ▁significantly ▁w ors ens ▁the ▁habitat ▁for ▁fish . ▁For ▁these ▁reasons ▁the ▁tunnel ▁is ▁used ▁only ▁on ▁the ▁rare ▁occasion ▁when ▁there ▁is ▁a ▁flo od ▁risk ▁in ▁the ▁Ver on ese ▁bas in . ▁ ▁Main ▁characteristics ▁ ▁L ength : ▁ 3 2 , 3 9 2 ▁ft ▁( 9 , 8 7 3 ▁m ) ▁ ▁Share ▁of ▁lead : ▁ 5 2 8 ▁ft ▁( 1 6 1 ▁m ) ▁a . s . l . ▁ ▁Open ing ▁level : ▁ 1 8 0 ▁ft ▁( 5 5 ▁m ) ▁a . s . l . ▁ ▁D ifference : ▁ 3 4 8 ▁ft ▁( 1 0 6 ▁m ) ▁ ▁Slo pe : ▁ 0 . 8 6 8 8 % ▁ ▁A verage ▁diameter : ▁ 2 6 ¼ ▁ft ▁( 8 ▁m ) ▁ ▁H yd ra ul ic ▁section : ▁ 5 4 2 ½ ▁sq . ▁ft ▁( 5 0 . 4 0 ▁m ² ) ▁ ▁Max imum ▁capacity : ▁ 1 7 , 6 5 0 ▁ft ³ ▁( 5 0 0 ▁m ³ / s ) ▁ ▁Water ▁speed ▁at ▁the ▁maximum ▁capacity