▁River ▁and ▁the ▁end or he ic ▁Car ri zo ▁P lain . ▁On ▁the ▁south , ▁the ▁Te h ach apis ▁wall ▁off ▁the ▁Tul are ▁Bas in ▁from ▁the ▁M oj ave ▁Des ert . ▁To ▁the ▁east , ▁the ▁Sierra ▁Nev ada ▁separate ▁the ▁San ▁Jo aqu in ▁d rain age ▁from ▁those ▁of ▁multiple ▁smaller ▁rivers ▁that ▁terminate ▁in ▁various ▁Great ▁Bas in ▁la kes . ▁From ▁north ▁to ▁south , ▁these ▁are ▁the ▁Car son , ▁Walker , ▁and ▁O w ens ▁R ivers . ▁The ▁s lop ing ▁all uv ial ▁fan ▁of ▁the ▁Kings ▁River ▁div ides ▁the ▁northern ▁San ▁Jo aqu in ▁Valley ▁from ▁the ▁Tul are ▁Bas in . ▁ ▁The ▁over wh el ming ▁majority ▁of ▁the ▁economic ▁base ▁in ▁the ▁San ▁Jo aqu in ▁River ▁waters hed ▁is ▁provided ▁by ▁agricult ure . ▁The ▁valley ▁is ▁widely ▁considered ▁one ▁of ▁the ▁most ▁product ive ▁far ming ▁regions ▁in ▁the ▁world , ▁and ▁the ▁top ▁four ▁U . S . ▁count ies ▁ranked ▁by ▁agricult ural ▁production ▁are ▁all ▁located ▁in ▁the ▁San ▁Jo aqu in ▁waters hed ▁and ▁Tul are ▁Bas in . ▁The ▁cro ps ▁grown ▁in ▁these ▁four ▁count ies ▁alone ▁are ▁val ued ▁at ▁over ▁$ 1 2 . 6 ▁billion ▁ann ually , ▁while ▁the ▁production ▁of ▁the ▁entire ▁valley ▁is ▁estimated ▁at ▁more ▁than ▁$ 1 4 . 4 ▁billion . ▁The ▁main ▁c rop ▁in ▁the ▁valley ▁by ▁annual ▁sales ▁is ▁cot ton , ▁but ▁more