▁before ▁w iden ing ▁into ▁a ▁narrow ▁flo od ▁plain ▁occupied ▁by ▁the ▁start ▁of ▁Dun ed in ' s ▁sub urban ▁area . ▁The ▁valley ▁wid ens , ▁and ▁is ▁hem med ▁in ▁by ▁ste ep ▁s lop es ▁and ▁occas ional ▁cl iff ▁faces ▁before ▁joining ▁the ▁northern ▁end ▁of ▁the ▁wide ▁plain ▁which ▁is ▁the ▁location ▁of ▁Dun ed in ' s ▁C BD ▁some ▁ ▁from ▁the ▁coast . ▁At ▁its ▁mouth , ▁the ▁valley ▁is ▁some ▁ ▁in ▁width . ▁ ▁Much ▁of ▁Dun ed in ' s ▁water ▁supply ▁comes ▁from ▁res er voir s ▁in ▁the ▁upper ▁reaches ▁of ▁the ▁Le ith ▁Valley . ▁These ▁include ▁Ross ▁Creek ▁Res er voir , ▁the ▁oldest ▁res er voir ▁still ▁in ▁active ▁use ▁in ▁New ▁Zealand , ▁and ▁S ull iv ans ▁Dam . ▁N umer ous ▁popular ▁walking ▁tracks ▁traverse ▁the ▁bush - cl ad ▁reserve ▁land ▁surrounding ▁this ▁res er voir . ▁ ▁The ▁sub ur bs ▁The ▁term ▁" Le ith ▁Valley " ▁can ▁be ▁used ▁to ▁refer ▁to ▁the ▁semi - r ural ▁settlement ▁which ▁lies ▁in ▁the ▁upper ▁reaches ▁of ▁the ▁valley , ▁or ▁- ▁more ▁generally ▁- ▁for ▁both ▁this ▁community ▁and ▁the ▁two ▁sub ur bs ▁which ▁lie ▁in ▁the ▁lower ▁valley , ▁Glen le ith ▁and ▁Wood h augh . ▁ ▁Le ith ▁Valley ▁Le ith ▁Valley ▁is ▁as ▁much ▁a ▁rural ▁settlement ▁as ▁a ▁sub urb , ▁though ▁it ▁does ▁lie ▁within ▁the ▁Dun ed in ▁city ▁boundaries ▁very