Penitencia Creek - Ecology

Ecology

Upper Penitencia Creek remains a Steelhead trout (Oncorhynchus mykiss) stream and according to two reports may have supported Coho salmon (Oncorhynchus kisutch) historically, based on habitat suitability analysis. The Santa Clara Valley Urban Runoff Pollution Prevention Program (SCVURPPP) developed a workplan for watershed analysis in 2006 as the stream was deemed potentially impaired by sediment from anthropogenic activities, this Limiting Factor Analysis reported results from an extensive snorkel sampling effort during spring and fall 2005 which indicated that the watershed supported between 1,300 and 1,500 age 1+ and older steelhead, of which age 2+ and older fish comprised approximately 5 to 10%, from approximately 3.5 miles (5.6 kilometers) upstream of the confluence with Coyote Creek upstream to natural waterfall barriers in Upper Penitencia Creek and Arroyo Aguague. With the exception of the man-made, historic rock baths confining the stream in Alum Rock Park, significant barriers to spawning runs were not identified. Although the structure on Upper Penitencia Creek in Alum Rock Park presents a significant partial barrier to fish passage, an engineering analysis to modify the barrier was completed in 2011. The City of San Jose, in conjunction with the Santa Clara Valley Transportation Authority (VTA) are planning to remove this barrier, a concrete weir related to the historic Youth Science Institute bridge, along with three other stream restoration projects with $2.5 million in funding from VTA as mitigation for environmental damages related to other VTA construction. The project is scheduled for completion in October, 2012.

In dry summers the creek goes dry about one mile below Alum Rock Park. Flows are diverted by the Santa Clara Valley Water District (SCVWD) to three off-channel percolation ponds at Noble Avenue, which in turn, recharge creek flows for about two miles below the ponds through the summer. However the diversion is also capable of drying the stream in late spring which may interfere with outmigrating steelhead smolts.

A Bay Area-wide study of which watersheds had the greatest potential for restoration for steelhead trout populations identified three streams in Santa Clara County: Upper Penitencia Creek, Stevens Creek and the Guadalupe River.