Laserfiche WebLink
(CSWRCB, 1989). The Chico area is situated on recent <br /> S"wcy/ Sao"° alluvial fan materials derived from volcanic sediments and <br /> She I N'Vg" ; ����. N mudflows originating in the hills to the east of Chico(DWR, <br /> �• `.� 1984).The alluvial deposits average about 40 to 50 feet in <br /> B O L IN A S MESA �\ `� thickness and consist of unconsolidated cobbles,gravel and <br /> STUDY AREA Sown <br /> Study sand,and minor amounts of clay.These deposits support a <br /> She shallow unconfined aquifer that is recharged directly by <br /> V .`.�`: infiltration from precipitation,local runoff,and discharge <br /> a't from subsurface sewage disposal. Older alluvium imme- <br /> diately underlies the recent alluvium and extends to depths <br /> of nearly 450 feet. It is characterized mostly by thick clay <br /> BOLINAS <br /> -__-__-_= layers and cemented sand and gravel.In this zone,ground <br /> water occurs mainly in thin uncemented sand and gravel <br /> lenses under semiconfined conditions,recharged by vertical <br /> ____________==- leakage from the overlying recent alluvium and from incised <br /> streams east of Chico. <br /> _-_ <br />