Flow in Big Chico Creek Streams are often described by mean annual discharge (km3/year. This provides a comparative idea of stream size, particularly for large rivers. For smaller streams, it is useful to an engineer who might be interesting in building a water supply reservoir, but nearly meaningless to the aquatic ecologist interested in its ability to support fish. A base-flow discharge would be much more relevant to the biologist. Even more useful is a plot of discharge against time. Maximum, mean, or median could be plotted.

Maximum shows the time of year storm events may be expected as well as how large they have been recorded to be. Because the maximum flow on a given day exceeds the typical flow by more than 10 times, a plot of mean flow looks like a scaled-down plot of maximum flow.

Median is the flow that half the time on that day the flow will be greater than and half the time it will be less than. It is the most useful predictor of how high the creek is likely to be on a given day.

From the above plots we can see that storm events big enough to raise Big Chico Creek significantly can occur any time from October through April and the creek is usually high from January through March and at base flow July through September. Base flow was 20 to 30 cfs at the historic USGS gauging station (between Bear Hole and the Golf Course. Since the lower part of the creek loses water in summer to evaporation and infiltration, base flow in the ecological reserve should be greater than at the USGS station. Data is currently being collected to test that prediction.

See real-time flow data on Big Chico Creek.

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Web Page by Paul Maslin email:(pmaslin@csuchico.edu)