▁Flo od plain ▁is ▁part ▁of ▁the ▁Trad itional ▁lands ▁of ▁the ▁N ari ▁N ari ▁and ▁M uth i ▁M uth i ▁Ab original ▁pe op les . ▁ ▁It ▁compr ises ▁an ▁extensive ▁( c . ▁) ▁flo od plain ▁of ▁the ▁lower ▁M urr umb idge e ▁River ▁and ▁its ▁trib ut aries , ▁including ▁the ▁confl u ence ▁of ▁the ▁M urr umb idge e ▁with ▁the ▁L ach lan ▁River , ▁with ▁numerous ▁sw amps ▁and ▁la kes . ▁ ▁The ▁extent ▁of ▁the ▁flo od plain ▁has ▁been ▁reduced ▁in ▁size ▁from ▁over ▁ ▁at ▁the ▁beginning ▁of ▁the ▁ 2 0 th ▁century ▁by ▁the ▁construction ▁of ▁d ams , ▁ir rig ation ▁systems ▁and ▁other ▁hyd ra ul ic ▁engineering ▁works , ▁with ▁the ▁water ▁in flow ▁decl ining ▁by ▁at ▁least ▁ 6 0 % ▁between ▁ 1 8 8 8 ▁and ▁ 1 9 9 8 . ▁ ▁A part ▁from ▁Y anga ▁National ▁Park ▁( est ab lished ▁in ▁ 2 0 0 5 ▁on ▁the ▁former ▁Y anga ▁Station ) ▁most ▁of ▁the ▁flo od plain ▁consists ▁of ▁commercial ▁ir rig ated ▁far ml and . ▁ ▁Bird s ▁A ▁ ▁area ▁of ▁the ▁flo od plain , ▁defined ▁as ▁the ▁maximum ▁area ▁of ▁contemporary ▁flo oding , ▁has ▁been ▁identified ▁by ▁Bird Life ▁International ▁as ▁an ▁Import ant ▁Bird ▁Area ▁( I BA ) ▁because ▁it ▁has ▁supported ▁up ▁to ▁ 6 5 0 , 0 0 0 ▁water bird