The Garcia River is a river on the northern coast of California, in southern Mendocino County. The river's watershed covers 144 square miles and its mainstem is 44 miles long. The watershed receives 45 inches of precipitation per year near the coast and 75 inches inland. The watershed's elevation ranges from sea level near the ocean to 2,470 …The Garcia River is a river on the northern coast of California, in southern Mendocino County. The river's watershed covers 144 square miles and its mainstem is 44 miles long. The watershed receives 45 inches of precipitation per year near the coast and 75 inches inland. The watershed's elevation ranges from sea level near the ocean to 2,470 feet in the Coast Range. The Garcia River empties into the Pacific Ocean just north of Point Arena. This place is called P'da Hau in the Native California Indians' language who reside on the outlet of the coast.