 Since Islais Creek is a culvert that carries storm water , domestic sewage , and industrial wastewater , it is possible for the sewage to overflow . Such overflow can cause a public health hazard as Islais Creek displays higher level of heavy metals , PCBs , bacteria , as well as organochlorines than other parts of the San Francisco Bay . 
 Since Islais Creek <a href='drop_aux' title='1'><mark>is</mark></a>a culvert <a href='null_relcl' title='2'><mark>that</mark></a><a href='uninflect' title='3'><mark>carries</mark></a> storm water , domestic sewage , and industrial wastewater , it <a href='drop_aux' title='4'><mark>is</mark></a>possible for the sewage to overflow . Such overflow can cause a public health hazard as Islais Creek <a href='uninflect' title='5'><mark>displays</mark></a> higher level of heavy metals , PCBs , bacteria , as well as organochlorines than other parts of the San Francisco Bay . 
Since Islais Creek a culvert carry storm water , domestic sewage , and industrial wastewater , it possible fir da sewage to overflow . Such overflow can cause a public health hazard as Islais Creek display higher level of heavy metals , PCBs , bacteria , as well as organochlorines than other parts of the San Francisco Bay .