ple ted ▁and ▁poll uted , ▁while ▁the ▁Gang ot ri ▁gla cier ▁that ▁fe eds ▁the ▁river ▁is ▁retre ating ▁hundreds ▁of ▁feet ▁each ▁year ▁( ex per ts ▁bl ame ▁climate ▁change ) ▁and ▁def or est ation ▁in ▁the ▁H imal ay as ▁is ▁causing ▁sub so il ▁streams ▁flow ing ▁into ▁the ▁G anges ▁river ▁to ▁dry ▁up . ▁Down stream , ▁India ▁controls ▁the ▁flow ▁to ▁Bang l adesh ▁with ▁the ▁Far ak ka ▁Bar rage , ▁ 1 0   kil om eters ▁( 6   mi ) ▁on ▁the ▁Indian ▁side ▁of ▁the ▁border . ▁Until ▁the ▁late ▁ 1 9 9 0 s , ▁India ▁used ▁the ▁bar rage ▁to ▁di vert ▁the ▁river ▁to ▁Cal cut ta , ▁to ▁keep ▁the ▁city ' s ▁port ▁from ▁dry ing ▁up ▁during ▁the ▁dry ▁season . ▁This ▁denied ▁Bang l ades hi ▁far mers ▁water ▁and ▁s ilt , ▁and ▁it ▁left ▁the ▁Sund ar ban ▁wet lands ▁and ▁mang ro ve ▁for ests ▁at ▁the ▁river ' s ▁delta ▁seriously ▁threatened . ▁The ▁two ▁countries ▁have ▁now ▁signed ▁an ▁agreement ▁to ▁share ▁the ▁water ▁more ▁equally . ▁Water ▁quality , ▁however , ▁remains ▁a ▁problem , ▁with ▁high ▁levels ▁of ▁ar sen ic ▁and ▁un tre ated ▁se w age ▁in ▁the ▁river ▁water . ▁ ▁India – P ak istan ▁ ▁Rec ently ▁India ▁starting ▁construct ing ▁K ish ang anga ▁Dam ▁thus ▁dep riv ing ▁Pakistan ▁of ▁its ▁ 3 3 % ▁water