Tri-Valley Creeks

a partnership for a sustainable tomorrow

Spot 6 - Arroyo Mocho at Granada Native Gardens

AdoptACreek 6sm

The Friends of the Arroyos have adopted this 700 foot section of the Arroyo adjacent to Granada Native Gardens. The section extends from about 500 feet upstream of Stanley Boulevard up past the garden to the trail connection to Murrieta Boulevard. The Livermore School District owns the creek, trail and garden property as part of Granada High School.

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  Arroyo Mocho looking upstream near Granada Native Gardens with Mocho Trail on the left.

Arroyo Mocho looking upstream near Granada Native Gardens with Mocho Trail on the left. The upper section of the Arroyo Mocho is more open with a gravel stream bed and the lower section has concrete blocks and dense vegetation along the bank. Trash comes from litter along the trail, windblown trash from Murrieta Boulevard and trash washed into urban storm drains and out to the creeks during storms. The 4th street storm drain outfall located about 800 feet above this site is one of the larger storm drains in Livermore collecting runoff from as far as Livermore High School.

The Arroyo Mocho would naturally be dry most of the year but starting in the 1960's with the construction of the State Water Project and the South Bay Aqueduct, the Arroyo Mocho has been used for artificial groundwater recharge. Dry season water in the Arroyo Mocho originates hundreds of miles away in the northern Sierra and flows down the Sacramento River, through the Delta and is pumped over the Altamont Hills and transported to the Arroyo Mocho via the South Bay Aqueduct. The water then flows 5 miles down the arroyo to this site, slowly percolating into the Groundwater Basin along the way. Informational displays at Granada Native Gardens help explain how the artificial stream recharge program works. It is common for the artificial stream flows to be turned off about one day a month.

In wet years winter storm flows, from the upper watershed, produce much larger flows that fill the Arroyo Mocho channel with fast moving often sediment filled water. These high flows discharge into the Alameda Creek which goes all the way to the San Francisco Bay. This winter runoff can carry trash the full 32 miles to the bay. Informational displays at the Granada Native Gardens also explain this watershed story and how Steelhead Trout would occasionally use the Arroyo Mocho channel in Livermore as passage to the upper canyons of the Arroyo Mocho.

Parking is available in Peppertree Plaza on Murrieta Boulevard.