orge ▁and ▁emer ging ▁at ▁the ▁former ▁min ing ▁site ▁of ▁Michigan ▁Bar . ▁The ▁entire ▁stretch ▁of ▁the ▁Cos umn es ▁River ▁between ▁the ▁confl u ence ▁of ▁the ▁for ks ▁and ▁a ▁point ▁one ▁mile ▁( 1 . 6   km ) ▁above ▁Michigan ▁Bar ▁define ▁the ▁El ▁Dor ado / Am ador ▁County ▁line ; ▁below ▁this ▁point , ▁the ▁river ▁flows ▁into ▁southern ▁Sac r amento ▁County . ▁ ▁The ▁Cos umn es ▁flows ▁west ▁through ▁Ran cho ▁M uri eta , ▁an ▁aff lu ent ▁outer ▁sub urb ▁of ▁the ▁Sac r amento ▁metropol itan ▁area . ▁Two ▁small ▁di version ▁d ams ▁cross ▁the ▁river ▁near ▁Van ▁V le ck ▁Park ▁just ▁up stream ▁from ▁the ▁town . ▁Below ▁Ran cho ▁M uri eta ▁the ▁Cos umn es ▁flows ▁through ▁an ▁agricult ural ▁valley , ▁turning ▁south west ▁near ▁Sl ough house . ▁A ▁few ▁miles ▁down stream ▁the ▁F ols om ▁South ▁Canal ▁cross es ▁under ▁the ▁Cos umn es ▁River ▁via ▁an ▁invert ed ▁si phon . ▁The ▁Cos umn es ▁continues ▁south west , ▁passing ▁Sh eld on ▁and ▁Wil ton , ▁receives ▁De er ▁Creek ▁from ▁the ▁right , ▁then ▁is ▁crossed ▁by ▁Highway ▁ 9 9 ▁near ▁El k ▁Gro ve . ▁Below ▁Highway ▁ 9 9 ▁it ▁enters ▁the ▁nearly ▁ ▁Cos umn es ▁River ▁Pres erve , ▁which ▁include ▁some ▁of ▁the ▁largest ▁remaining ▁wet lands ▁and ▁rip arian ▁areas ▁in ▁the ▁Central ▁Valley . ▁It ▁enters ▁the ▁Sac r