Figure 1. O. mykiss captured in the Calaveras River rotary screw trap at Shelton Road.

The Calaveras River rotary screw trap at Shelton Road (RM 28) was operated only one day between March 14 and April 3, 2011 due to flood control releases from New

Hogan Reservoir that exceeded 300 cfs. A total of 4 O. mykiss were captured, increasing the season total to 562 (Figure 2). Three of the O. mykiss captured were YOY (>100 mm; Figure 1) and rated as fry, and one was Age 1+ (100-299 mm) and was rated as silvery parr. Average forklengths and weights of measured O. mykiss are provided in Table 1.

No Chinook salmon have been captured this season.

One instantaneous temperature reading of 52.0�F (3/16) was recorded and two turbidity readings of 2.99 NTU and 3.23 NTU (3/15 and 3/16, respectively) were recorded at the trap during the reporting period. Daily average combined flows from New Hogan Dam (NHG) and Cosgrove Creek (COS) fluctuated between 215 cfs and 6,967 cfs, and at Bellota (MRS) flows fluctuated between 237 cfs and 7,635 cfs.

No trap efficiency experiments were conducted during the reporting period.

Table 1. Biosampling data for O. mykiss captured at Shelton Road between March 14 and April 3, 2011. Parentheses indicate range.

The Stanislaus River rotary screw trap at Oakdale (RM 40) sampled continuously during the reporting period. A total of 955 juvenile Chinook salmon and 9 juvenile O. mykiss were captured, bringing the season totals to 42,238 and 21, respectively. Daily catch of Chinook salmon ranged between 16 and 112 individuals. Average forklengths and weights of Chinook salmon and O. mykiss are provided in Table 2 for the 816 Chinook and 9 O. mykiss that were measured. Most of the measured Chinook were fry (n=377) or parr (n=329), but smolts (n=110) were also recorded. Only two of the O. mykiss were rated and both were smolts (n=2; Figure 3).

Table 2. Biosampling data for Chinook salmon and O. mykiss captured and measured at Oakdale between March 14 and April 3, 2011.

Instantaneous temperature recorded at the trap ranged from 47.8�F to 55.2�F, and turbidity ranged from 1.86 NTU to 30.80 NTU (Figure 5). Daily average flows at Goodwin Dam (GDW) increased from 201 cfs and 1,344 cfs, and flows at Ripon (RIP) ranged from 250 cfs to 1,598 cfs (Figure 4).

One trap efficiency experiment was conducted with naturally spawned juvenile Chinook salmon marked caudal fin green (CFG). Preliminary efficiency estimate from the release was 8.4% at flows of 204 cfs and are provided in Table 3.

Table 3. Trap efficiency tests conducted at Oakdale between March 14 and April 3, 2011.

Figure 4. Daily Chinook salmon catch at Oakdale, and Stanislaus River flow recorded at Goodwin Dam (GDW) and Ripon (RIP) in 2011.

Figure 5. Daily Chinook salmon catch at Oakdale in relation to instantaneous turbidity recorded at the trap in 2011.

The Stanislaus River rotary screw trap at Caswell State Park (RM 8) sampled continuously during the reporting period and a total of 42 juvenile Chinook salmon were captured, increasing the season total to 443. Daily catch ranged between 0 and 10 Chinook salmon (Figure 6).  

One O. mykiss was captured during the reporting period and this was the first individual captured this season.

No trap efficiency experiments were conducted during the reporting period.

Instantaneous temperature recorded at the trap ranged from 50.4�F and 59.0�F, and turbidity ranged from 3.04 NTU to 28.00 NTU. Daily average flow at Ripon (RIP) ranged from to 250 cfs to 1,598 cfs.

Figure 6. Daily Chinook salmon catch at Caswell, and Stanislaus River flow recorded at Ripon (RIP) in 2011.

The Tuolumne River rotary screw trap at Waterford (RM 30) operated continuously during the reporting period. A total of 141 juvenile Chinook salmon fry were captured bringing the season total to 4,016. Daily catch ranged between 1 and 21 Chinook (Figure 7). Average forklengths and weights for all 141 Chinook salmon are provided in Table 4. The majority of the measured Chinook were fry (n=104), but parr (n=18) and smolts (n=19) were also recorded.

Table 4. Biosampling data for Chinook salmon captured and measured at Waterford between March 14 and April 3, 2011. Parentheses indicate range.

No O. mykiss were captured during this reporting period.

Instantaneous temperature taken at the trap ranged from 48.0�F to 51.8�F, and turbidity ranged from 1.76 NTU to 7.33 NTU. Daily average flow at La Grange (LGN) increased from 2,680 cfs to 8,360 cfs.

No trap efficiency experiments were conducted during the reporting period.

Figure 7. Daily Chinook salmon catch at Waterford, and Tuolumne River flow recorded at La Grange (LGN) and Modesto (MOD) between December 1, 2010, and April 3, 2011.

Figure 8. Chinook salmon captured in the Tuolumne River rotary screw traps at Grayson.

Due to increased flows, resulting from flood control and rain events, the Tuolumne River rotary screw traps at Grayson (RM 5) were not operated continuously, and sampled for eleven days during the reporting period. A total of 8 Chinook salmon were captured, bringing the season total to 1,466 (Figure 8). Average forklengths and weights are provided in Table 5 for seven of the Chinook salmon captured. Most of the Chinook captured and measured were rated as parr (n=4), but a fry (n=1) and smolt (n=2) were also observed.

Table 5. Biosampling data for Chinook salmon captured and measured at Grayson between March 14 and April 3, 2011. Parentheses indicate range.

Instantaneous temperature taken at the trap ranged from 48.9�F to 54.5�F, and turbidity ranged from 2.27 NTU to 6.65 NTU. Daily average flows at Modesto (MOD) increased from 3,060 cfs to 9,110 cfs (Figure 9).

No trap efficiency experiments were conducted during the reporting period.

Figure 9. Daily Chinook salmon catch at Grayson, and Tuolumne River flow recorded at La Grange (LGN) and Modesto (MOD) between January 1 and April 3, 2011.

The Mokelumne River rotary screw trap at Vino Farms (RM 54) was sampled intermittently, and a total of 139 juvenile Chinook salmon were captured during the reporting period, bringing the season total to 29,437.

Average daily flow from Camanche Reservoir (CMN) increased from 1,165 cfs to 3,405 cfs (Figure 10). Instantaneous temperature ranged from 48.7�F to 51.6�F, and instantaneous turbidity ranged between 2.64 NTU and 7.20 NTU.

One O. mykiss was captured during the reporting period, increasing the season total count to nine.

Due to an increase in flow (>1,500 cfs) that exceeds the weirs operational capacity of the weir (ie, ability to remain afloat), the resistance boards and barrels that assist the weirs flotation were removed on April 4. The Vaki Riverwatcher detected a total of 1,382 Chinook salmon passing upstream of the Stanislaus River Weir during the monitoring season with the last detection on January 13.

One adult O. mykiss (350 mm) was detected passing upstream on March 14 increasing the season total to six O. mykiss. The species most frequently detected by the Riverwatcher during the reporting period were Sacramento sucker, carp, and black bass (Table 6).

Daily average flow in the Stanislaus River at Goodwin Dam (GDW; RM 58) increased from 201 cfs to 1,726 cfs on April 5 (Figure 12). Flow at Ripon (RIP; RM 15) fluctuated between 250 cfs and 1,598 cfs. Note: flows downstream of Goodwin Dam may differ from dam releases due to irrigation, precipitation and other factors.

Instantaneous water temperature measured at the weir ranged between 49.6˚F and 58.2˚F, and daily average water temperature at Ripon (RPN; RM 15) ranged between 50.9˚F and 59.2˚F (Figure 13). Instantaneous turbidity ranged between 2.02 NTU and 4.97 NTU (Figure 14). Instantaneous dissolved oxygen at the weir ranged between 9.60 mg/L and 11.55 mg/L, and daily average dissolved oxygen at Ripon (RPN; RM 15) ranged from 8.42 mg/L to 9.66 mg/L (Figure 15).

Table 6. Net passage counts for all species between March 14 and April 4, 2011 at the Stanislaus River Weir.

Figure 12. Daily upstream adult Chinook passage at the Stanislaus River weir in relation to daily average flow (cfs) recorded in the Stanislaus River at Goodwin (GDW) and Ripon (RIP), and in the San Joaquin River at Vernalis (VNS) in 2010 and 2011.

During the reporting period, flow in the San Joaquin River at Vernalis increased from 8,091 cfs to 28,575 (Figure 18). Water temperature in the San Joaquin River ranged from 50.7�F to 61.0�F at Vernalis, from 51.4�F to 61.6�F at Mossdale, and from 52.3�F to 62.3�F at Rough 'n Ready Island (Figure 19). Average daily dissolved oxygen (DO) in the San Joaquin River decreased from 9.9 mg/L to 6.9 mg/L in the deep water ship channel (measured at Rough 'n Ready Island), and from 10.5 mg/L to 6.9 mg/L at Mossdale (Figure 20).

Mean daily pumping at the C.W. Jones Pumping Plant (federal pumps previously known as Tracy Pumping Plant) ranged between 0 cfs and 3,719 cfs (Figure 21). Mean daily pumping at the Harvey O. Banks Pumping Plant (state pumps) fluctuated between 0 cfs and 5,506 cfs. Combined total exports (state and federal pumps) during this period ranged from 0 cfs to 7,627 cfs.