Stanislaus River Weir Update                                                                    October 23, 2006

October 9 through October 22, 2006
 

A total of 266 Chinook passed upstream of the weir between October 9 and October 22 increasing the season total to 510.  The season total to date this year is significantly less than the season totals during the same time periods as past years (Figure 1).  Chinook passage counts ranged from 11 to 43.  Total-lengths ranged from 349 mm to 1063 mm (avg = 720 mm).  Other fish species observed included striped bass, Sacramento blackfish, Sacramento pikeminnow, Sacramento sucker, and goldfish.  

 Figure 1.   Adult Chinook Passage 2003 to 2006.

One 378 mm O.mykiss ad-clip (i.e., indicating presence of coded wire tag and/or hatchery raised) passed through the weir on October 11 @ 1:08 pm (Figure 2).  This is the first ad-clip O.mykiss that we have observed at the weir to date.  This year to date we have observed a total of two O.mykiss (including this one) pass the weir.

Figure 2. A 378 mm (depth: 90 mm) O.mykiss (left) and 592 mm (depth: 141 mm) Chinook (right) passing the weir on October 11.

A total of 14 ad-clipped Chinook (i.e., indicating presence of coded wire tag) passed upstream of the weir during the sampling period.  Total-lengths ranged from 542 mm to 958 mm (avg = 728 mm; Table 1).

Table 1.  Date, total length and sex of ad-clipped Chinook passing upstream of the weir between October 9 and October 22, 2006.
 

Environmental conditions fluctuated at the weir site during the sampling period.  Flow at Orange Blossom Bridge (OBB) ranged from 1,293 cfs to 1,313 cfs; turbidity ranged between 0.2 NTU and 1.2 NTU; and dissolved oxygen (DO) ranged between 10.13 mg/L and 11.15 mg/L.  DO at Rough 'n Ready Island (RRI) in the San Joaquin River's Deep Water Ship Channel ranged from 7.38 mg/L to 78.26 mg/L.  Daily instantaneous water temperature at the Stanislaus River weir ranged from 52.5ºF to 55.9ºF.
     

For more details on 2006 Stanislaus River adult Chinook passage at the weir and how it relates to San Joaquin and Stanislaus environmental conditions, visit the webpage at www.stanislausriver.com/weir/data.htm. 

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