▁ge ographic ▁middle ▁of ▁the ▁bas in , ▁growth ▁was ▁ 5 1 . 5 % ▁between ▁ 1 9 9 0 ▁and ▁ 2 0 0 3 , ▁the ▁highest ▁in ▁the ▁San ▁Jo aqu in ▁bas in . ▁Most ▁of ▁the ▁major ▁cities ▁lie ▁on ▁the ▁State ▁Route ▁ 9 9 ▁cor rid or , ▁which ▁runs ▁along ▁the ▁entire ty ▁of ▁the ▁San ▁Jo aqu in ▁Valley ▁and ▁forms ▁the ▁primary ▁thorough fare ▁for ▁the ▁valley . ▁Inter state ▁ 5 ▁provides ▁the ▁major ▁transport ation ▁route ▁for ▁the ▁west ▁side ▁of ▁the ▁valley . ▁ ▁Land ▁cover ▁in ▁the ▁waters hed ▁is ▁pre domin antly ▁agricult ure ▁and ▁forest , ▁and ▁large ▁exp ans es ▁of ▁shr ub land ▁and ▁sem iar id ▁fo oth ill ▁terrain ▁also ▁occup y ▁port ions ▁of ▁the ▁bas in ▁in ▁addition ▁to ▁a ▁growing ▁urban ▁percentage . ▁Ir rig ated ▁land ▁covers ▁ 3 0 % ▁of ▁the ▁waters hed ▁followed ▁by ▁for ested ▁areas ▁in ▁addition ▁to ▁national ▁forest ▁and ▁park ▁land ▁that ▁en comp ass ▁ 2 6 . 8 % ▁of ▁the ▁total ▁land ▁area . ▁Bu ilt - up ▁areas ▁use ▁a ▁much ▁smaller ▁percentage ▁of ▁the ▁waters hed , ▁at ▁just ▁ 1 . 9 %. ▁In ▁the ▁San ▁Jo aqu in ' s ▁direct ▁d rain age ▁region ▁( not ▁including ▁the ▁Tul are ▁Bas in ) ▁agricult ural ▁cover ▁was ▁ 1 9 . 2 %, ▁for ests ▁emb rac ed ▁ 2 8 .