▁that ▁the ▁gates ▁should ▁be ▁replaced ▁by ▁a ▁conventional ▁p ound ▁lock , ▁but ▁this ▁was ▁not ▁carried ▁out . ▁However , ▁in ▁ 1 8 5 2 ▁a ▁lock ▁was ▁constructed , ▁although ▁the ▁gates ▁also ▁remained ▁in ▁place . ▁The ▁lock ▁was ▁re built ▁and ▁short ened ▁in ▁ 1 9 0 0 , ▁and ▁a ▁second ▁lock ▁constructed ▁beside ▁it ▁in ▁ 1 9 3 1 . ▁High er ▁flo od g ates ▁and ▁walls ▁were ▁added ▁in ▁ 2 0 0 0 ▁to ▁prevent ▁the ▁in und ation ▁of ▁the ▁Lee ▁Navigation ▁when ▁the ▁level ▁of ▁the ▁t ide ▁in ▁the ▁cre ek ▁exceed ed ▁the ▁level ▁in ▁the ▁navigation . ▁ ▁Access ▁from ▁the ▁cre ek ▁to ▁Bow ▁Back ▁R ivers ▁was ▁alter ed ▁in ▁the ▁ 1 9 3 0 s ▁as ▁part ▁of ▁an ▁upgrade ▁carried ▁out ▁to ▁improve ▁the ▁water ways ▁and ▁to ▁provide ▁employ ment . ▁The ▁Pres c ott ▁Channel ▁was ▁constructed ▁to ▁by pass ▁the ▁t ide ▁mill s , ▁and ▁gave ▁access ▁from ▁the ▁cre ek ▁to ▁the ▁Three ▁M ills ▁Wall ▁River ▁and ▁the ▁Water works ▁River . ▁The ▁lock ▁and ▁sl u ice ▁structure ▁at ▁the ▁mouth ▁of ▁the ▁new ▁channel ▁became ▁dis used ▁in ▁the ▁ 1 9 6 0 s ▁and ▁was ▁subsequently ▁removed , ▁but ▁a ▁new ▁structure ▁capable ▁of ▁handling ▁ 3 5 0 - ton ne ▁b arg es ▁has ▁been ▁built ▁as ▁part ▁of ▁the ▁upgrade ▁to ▁the ▁water ways ▁for ▁the ▁