2007 Monitoring Review

Sampling Results (2004-2007)

The relevant water quality objectives addressed in the Big Chico Creek monitoring program were: temperature, dissolved oxygen, pH, conductivity, sediment, bacteria, nutrients, stream flow, habitat and biological surveys.

Ten stations were monitored monthly from May through October, and twice during storm events. These ten stations represent the 3 regions of Big Chico Creek (mountain, foothill and valley) to allow for a more comprehensive look at the health of the watershed.

Water temperature, EC, and TDS varied the greatest along the length of the study area with a general trend toward higher values as you move down through the watershed from the mountain zone to the valley zone. The seasonal pattern in temperature, EC, and TDS, was also influenced by elevation, flow and landuse and values were highest in the fall in the lower elevations.

Temperature recorders were installed in the upper reaches of the creek and indicate poor conditions for salmon during the months of July and August. 

Discharge measurements were taken each sampling event and flows were highest in the spring and lowest in the fall. Field measurements were correlated with the USGS gauge located near Bidwell Golf Course. There is an additional USGS gauge located downstream at Rose Avenue, but its data is not readily available.  Some of the functions at these gauges need to be repaired. It is recommended that both gauges be brought back up to optimal conditions with regular maintenance and easy access to data for comparison. 

Sediment and turbidity levels were low and closely linked to summer low flow conditions. Effects of erosion were not noted in the samples collected during summer months, but were higher during winter months.

Concentrations of E. coli bacteria were elevated for the lower watershed and exceeded basin plan water quality objectives for contact recreation, warranting further investigation.  Samples were collected at five sites during the months of September, October, and February. It is recommended that monitoring be expanded to determine if the geometric means truly represent a health issue for contact recreation. Possible sources include: pet waste (dogs, livestock), septic systems, sewer leaks, homeless encampments, etc. Nitrogen and phosphorus nutrients were also low in concentration with the exception of samples collected at the mouth.

Aquatic macroinvertebrates were collected and archived for future reference and analysis.

Overall, the Big Chico Creek watershed seems to be in relatively good condition with seasonal patterns related to both stream flow and land use. Impacts of land use are sometimes difficult to detect so information will have to be collected over a long temporal scale to determine any variation due strictly to land use.

The Alliance plans to continue the current monitoring effort. Also, they recently received support from the State Water Board's Consolidated Grants Program and the Sierra Nevada Alliance to expand the program to include objectives to track two large restoration projects through pre-post restoration site monitoring, and expand bioassessment to additional sites through 2008. In addition, the Alliance received support from the Stewardship Council during the 2006/2007 school year to initiate a school-based “Youth Stream Team” program linking our existing on-going monitoring objectives with the learning needs of local students.