▁of ▁ ▁of ▁water ▁per ▁day ▁( g pd ), ▁though ▁oper ational ▁characteristics ▁of ▁the ▁, ▁ ▁pipeline ▁to ▁the ▁city ▁limits ▁capacity ▁to ▁half ▁that . ▁ ▁The ▁Rock ▁Creek ▁Plant ▁output ▁remains ▁steady ▁year ▁round ▁at ▁about ▁. ▁ ▁The ▁H . D . ▁Taylor ▁treatment ▁plant ▁obtain s ▁water ▁from ▁the ▁Will am ette ▁River , ▁and ▁has ▁been ▁expanded ▁at ▁least ▁four ▁times ▁since ▁it ▁was ▁first ▁constructed ▁in ▁ 1 9 4 9 . ▁ ▁Its ▁output ▁var ies ▁season ally ▁according ▁to ▁demand , ▁producing ▁from ▁ ▁per ▁day , ▁though ▁it ▁has ▁a ▁capacity ▁of ▁ ▁per ▁day . ▁ ▁The ▁total ▁res er voir ▁capacity ▁is ▁, ▁though ▁measures ▁to ▁volunt arily ▁reduce ▁water ▁usage ▁begin ▁when ▁res er voir ▁levels ▁fall ▁below ▁ 9 0 % ▁of ▁capacity , ▁and ▁become ▁mand atory ▁at ▁ 8 0 % ▁or ▁below . ▁ ▁As ▁part ▁of ▁its ▁on going ▁water - con serv ation ▁program , ▁the ▁water ▁department ▁joint ly ▁publish es ▁a ▁guide ▁to ▁water - efficient ▁garden ▁plants . ▁ ▁Green ▁power ▁According ▁to ▁the ▁federal ▁Environment al ▁Prote ction ▁Agency ▁report ▁on ▁its ▁" green ▁power ▁communities ", ▁Cor v all is ▁is ▁among ▁the ▁top ▁cities ▁in ▁the ▁nation ▁in ▁terms ▁of ▁bu ying ▁electric ity ▁produced ▁from ▁renew able ▁resources . ▁Cor v all is ▁purch ases ▁more ▁than ▁ 1 2 6 ▁million ▁kil ow att - h ours ▁of ▁green ▁power ▁ann ually , ▁which ▁amounts