Low river/stream flows
Posted: Fri Aug 28, 2020 9:10 am
Now at the end of August, given a relatively low precipitation winter, summer with less thunderstorms, and a hot August, rivers and streams are at significantly lower levels than normal and water temperatures are near their seasonal least cool (Some would say warmest haha.) The below CDEC link lists stream gauges by basin, a few of which are at higher elevations though most are not of interest down at low elevations. For those interested in actually getting in water for fun, this is the optimal time to do so as otherwise our days rapidly become shorter, air temperatures drop, and so do stream and lake water temperatures.
http://cdec.water.ca.gov/dynamicapp/getAll?sens_num=20
Some of the higher gauges also show which streams are at or near zero flow that is a good indication why some streams that normally seem large enough to support large trout actually do not. If a stream during some years late season has no flow or near zero flows as is the case with many west side Sierra Nevada streams, that may not be able to support trout even if water still exists in deeper larger pools because of unpleasant for fish water temperatures and especially a lack of oxygen in water. Such waters also tend to suffer increasing algae growth that can further deplete oxygen except at surface areas due to stratification.
Current charts show Cherry Creek above Cherry Valley Reservoir and Falls Creek above Hetch Hetchy Reservoirs has zero BRT flows, a reflection of the granite geology in those basins where water tends to flow off without storage. Such flows may not actually be no water as trickling water may still exist. Further north areas with volcanic geology tend to release water more slowly from their deeper sediments, thus retain at least modest flows.
http://cdec.water.ca.gov/dynamicapp/getAll?sens_num=20
Some of the higher gauges also show which streams are at or near zero flow that is a good indication why some streams that normally seem large enough to support large trout actually do not. If a stream during some years late season has no flow or near zero flows as is the case with many west side Sierra Nevada streams, that may not be able to support trout even if water still exists in deeper larger pools because of unpleasant for fish water temperatures and especially a lack of oxygen in water. Such waters also tend to suffer increasing algae growth that can further deplete oxygen except at surface areas due to stratification.
Current charts show Cherry Creek above Cherry Valley Reservoir and Falls Creek above Hetch Hetchy Reservoirs has zero BRT flows, a reflection of the granite geology in those basins where water tends to flow off without storage. Such flows may not actually be no water as trickling water may still exist. Further north areas with volcanic geology tend to release water more slowly from their deeper sediments, thus retain at least modest flows.