chinook salmon populations in the Napa River basin have not been established, but the river provides appropriate habitat for salmon and its location near the entrance to the Sacramento/San Joaquin Rivers make it likely that salmon would have at least ventured into the Napa River. In 2013, a genetics study of Napa River chinook salmon revealed that two adults migrated from the Klamath River and successfully spawned in the Napa River, since four juvenile chinook collected from the Napa River in 2010 were proved to be siblings from the close similarity of their DNA and that the latter was characteristic of Klamath River chinook. These findings have important implications for the protection of the federally endangered Coastal California Chinook Salmon ESU since the Napa River, nor any stream in the Bay Area, was included in this ESU. The Napa River basin is estimated to have historically supported a spawning run of 6,000–8,000 steelhead, and as many as 2,000–4,000 coho salmon (Oncorhynchus kisutch). By the late 1960s, coho salmon were extirpated from the watershed and the steelhead population is now reduced to less than a few hundred adults. Flow reductions in key rearing streams have reduced food availability for juvenile steelhead, causing reduced growth and survival. Recently, a chum salmon (Oncorhynchus keta) was caught in the river. In addition, a fourth salmon species, sockeye salmon (Oncorhynchus nerka), was also identified in the Napa River. Although diminished, the Napa River basin continues to support a fish community of greater diversity than even the Sacramento and San Joaquin River systems, including a nearly intact community of sixteen native fish species, including Steelhead, fall-run Chinook salmon, Pacific (Lampetra tridentata) and river lamprey (Lampetra ayresi), hardhead (Mylopharodon conocephalus), hitch (Lavinia exilicauda), tule perch (Hysterocarpus traski), and Sacramento splittail (Pogonichthys macrolepidotus). Because of this diversity the Napa River has been prioritized for special protection. White sturgeon (Acipenser transmontanus) and many other native and non-native fishes currently utilize the Napa River watershed. The California golden beaver (Castor canadensis subauraticus) was historically extant. Recently beaver have recolonized the Napa River and have been documented in Napa as well as near Rutherford and Oak Knoll. Restoration As part of urban renewal in the 1970s, a concrete cover was removed from culverted sections of the Napa Creek, re-exposing the water to daylight. There is some debate as to whether this constituted one of the country's earliest "daylighting" projects, since the