text_combined: southern trails cancels calif part pipeline conversion state regulations forces questar cancel part southern trails salt lake city based questar corp went bid earlier month four new compressors complete conversion work east california portion 705 mile southern trails pipeline san juan basin long beach port area southern california portion converted oil pipeline california border four corners area new mexico open june 1 next year questar spokesman said monday unlikely almost 300 mile portion former oil pipeline california brought natural gas service due state regulatory provisions make uneconomic prospect customers leave local supplier part gas supplies questar currently looking optional uses potential buyer portion project whether pipeline proposed 110 mmcf supplies gets california would depend takeaway capacity border new operator california side might pipeline questar spokesperson said