Creek was the boundary of the mission lands and the Rancho Arroyo de la Alameda granted to Jose de Jesus Vallejo, who built a flour mill near the mouth of Niles Canyon. The mill and the importance of the canyon as a passage through the hills led to growth of Niles (which in 1956 became part of Fremont, California) in the 1850s. A favorable climate, excellent soils, and a fast-growing population helped agriculture to boom. Early roads led to landings where small ships would load grain and other foodstuffs for transport to market. Alameda Creek is the most important stream in Alameda County. From this Creek is derived the name of the County. Alameda Creek was the former boundary between Contra Costa and Santa Clara Counties during the period from 1850, when Contra Costa and Santa Clara Counties were formed, to 1853 when Alameda County was carved from the two Counties. The portion of Alameda County south of Alameda Creek is the only part of Alameda County that is not derived from Contra Costa County. Completion of the Central Pacific Railroad through Niles Canyon in 1869 was essential to completion of First transcontinental railroad that terminated at Alameda Terminal and Oakland Long Wharf that same year. The Western Pacific was also routed through Niles Canyon, connecting Sacramento, California and San Jose, California in 1906. The creek bed had once been used as a gravel quarry. When the gravel pits were flooded by water purchased by the public for groundwater recharge of the Niles Cone, the gravel harvesters began to daily pump out enough water to meet the needs of 30,000 people down the creek into San Francisco Bay. After the pumping was declared to be an illegal waste the Alameda County Water District acquired the quarry in 1975. In May 2015, vandals damaged an inflatable dam across the creek in Fremont, releasing 50 million gallons (190 million litres) of drinking water into San Francisco Bay. Alameda Creek watershed Alameda Creek is the largest watershed within the southern San Francisco Bay, draining 700 square miles (1,813 square kilometers), or about 20% of the total drainage area for the South Bay. Two-thirds of the watershed is in Alameda County including the reach through the Sunol Valley, the rest is in Santa Clara County. The tributaries of Alameda creek include Arroyo de la Laguna, Arroyo Valle, San Antonio Creek and Calaveras Creek, whose