Through the 1998 season, 49 different sites in 19 tributaries were sampled to observe 3008 juvenile chinook. Figure 1 shows the tributaries of the Sacramento River between Keswick Dam and Chico. Stream kilometer (str km), the distance from the tributary’s confluence with the Sacramento River to the sample site, is used throughout this report to define sample sites. Table 1 provides a summary of sampling results from each site and date.
The following provides a quick discussion of individual creeks in order from south to north:
Little Butte Creek, while outside the geographic zone we have been focusing on, was included because it was sampled on a class field trip and found to contain rearing juvenile chinook. It differs from all the other streams sampled in that it drains a large marshy area that is still an active part of the Sacramento River floodplain and is maintained as perennial water by connection to an irrigation canal.
Big Chico Creek, being a relatively large stream, was virtually impossible to sample under the sustained high flow conditions of 1998.
Kusal Slough (Rock Creek) had been extensively sampled in the past, so was not emphasized this year. One set of samples were taken at various sites on 3/27/98 to permit a relatively accurate population estimate. Unfortunately the lower 4 km were still too high to sample due to the river backwater effect.
Mud Creek was intended to be our primary focus in 1998, with intent to get population estimates on several dates. Consistently high flow largely foiled that plan. On most sample dates, flow was too high to obtain quantitative samples, and even on good days, no samples could be obtained within about 4 km of the river.
Pine Creek is difficult to sample at best. This year all attempts at quantitative sampling in Pine Creek were frustrated by high flow.
Rice Creek was sampled for the first time this year. We were able to obtain trespass permission for only one site, which was impossible to sample quantitatively. However we found both juvenile chinook and steelhead at that site. Based on the characteristics of the creek and the fact that we found juvenile chinook at a site nearly 11 km from the river, one can hypothesize that Rice Creek supports a good population of rearing chinook.
Jewett Creek was sampled for the first time this year. It is a small stream with a strong tendency to go dry in the lower, somewhat degraded portion. While juvenile chinook were present and appeared to emigrate successfully this year, that is probably not typical. From reports of local residents, it seems likely that in most years any juvenile chinook entering Jewett would be trapped and lost. Probably few enter such a small creek.
Toomes Creek populations seemed similar to last year but were difficult to quantify because of high flows. Many juveniles enter Toomes, but they do not go far upstream.
Thomes Creek is large and difficult to sample even in a low water year. This year it was essentially impossible.
McClure Creek is quite small. Last year many juvenile chinook entered it only to become trapped. This year also produced high numbers, but all appeared to migrate out successfully. Last year it was a salmon trap; this year it was an excellent rearing area.
Elder Creek was difficult to sample under the high flow conditions prevalent this year. We demonstrated presence of juvenile chinook, but were unable to get any quantitative data.
Dye Creek, as usual, had lots of juvenile chinook. Last year we projected an upstream limit of 6.7 km, but this year we were able to sample that reach of stream and found chinook below but not above an old dam at km 6.3. That dam appears no worse than some obstructions we have found juvenile salmon above, but very few make it even to the dam because of the low-water crossing at Shasta Boulevard.
Coyote Creek and Oat Creek were not sampled this year.
Salt Creek seemed to be good rearing habitat this year. Consistently high flows in the Sacramento River kept water well above the low-water crossing on Salt Creek Road, eliminating that as a barrier this year.
Red Bank Creek was sampled extensively at stream km 8.4. Habitat there looked good, but no chinook were found. Very probably reduction in numbers by the partial barrier at the railroad and relatively poor habitat in the reach immediately above Highway 99W combine to prevent juveniles from moving upstream to the better habitat.
Reed’s Creek was sampled extensively at stream km 2.3. The habitat there and elsewhere in the creek was very poor, with a continuous shallow run and almost no cover. No chinook were found. Reeds Creek has degraded significantly in high flow events of the last two years. Currently almost no habitat exists for chinook rearing.
Dibble Creek is highly degraded with shallow, wide runs and almost no cover beyond 0.5 km from the river. Schools of chinook juveniles were present at the Adobe Road bridge, but none could be found an additional 0.5 km upstream.
Blue Tent has also degraded substantially in the last two years, eroding wider and shallower with almost no cover. Juvenile chinook were present at 0.4 km from the river, but none could be found at stream km 3.
Anderson Creek. No chinook were found at stream km 4.2. The odor and color of water and especially of the sediment suggested that low oxygen conditions were common. The stream in its current degraded condition probably does not support significant chinook rearing. If water quality was better, they would probably be there.
Ash Creek. Terry Moore reported seeing juvenile salmon rearing at stream km 4.3 in 1994. We sampled extensively with seine and electrofishing equipment but could find no chinook upstream of km 1.82. In 1994 Ash Creek provided quality habitat, with many deep pools shaded by extensive growth of button willow. Peak flows in the last two years, perhaps exacerbated by overgrazing in the drainage basin, caused severe habitat damage, probably reducing the attractiveness of the stream.
Bear Creek, being a relatively large stream, was virtually impossible to sample under the sustained high flow conditions of 1998.
Dry Creek, tributary to Bear at 1 km from the river, contained a few juvenile chinook, including one of winter-run size. However, Dry is a small creek and probably does not support rearing in drier years.
Stillwater Creek was sampled extensively without finding any chinook juveniles upstream of about 0.5 km. Since it has good habitat and a reasonable gradient, the lack of fish remains a mystery.
Churn Creek has a low gradient and lots of good rearing habitat. It is rather large, so quantitative sampling was impossible this year, but juvenile chinook were found up to 17.6 km from the river. Presence of very small juveniles at substantial distance from the river strongly suggest that a significant amount of spawning occurred in the creek.
Olney Creek had juvenile salmon at km 0.54 but none at stream km 1.4. This is consistent with last years data where we found a few at stream km 1.3 and consistent with the multiple little barriers inherent in the small size of the creek. We did not attempt to look for evidence of spawning by steelhead or late-fall chinook as reported last year because that is outside the scope of this study.