California Creek Subwatershed

California Creek example of entrenched channel locked in place and unable to access its floodplain.

California Creek Project Area

Area Summary: California Creek is a tributary to the Ruby River with a 15,451 acre watershed. California Creek and its major tributary Harris Creek have been notably impacted by placer mining. Stream and fish surveys conducted by USFS revealed high suitability potential for native westslope cutthroat habitat, and genetic testing revealed that remnant westslope cutthroat trout were present.  Northern slopes have banks that are well vegetated with alder, dogwood, river birch and willows.

An eroding bank on California Creek

Impairments: Historic placer mining in upper reaches contributes 57% of the total sediment load to the California Creek sub-watershed. Dredge activities have caused the entire stream and floodplain to be re-established at a lower elevation, resulting in a confined valley bottom and stream locked in place. Due to this lowering of base elevation, gullies have been formed and are actively eroding contributing periodic pulses of sediment.Agricultural impacts including grazing practices, corral placement, riparian clearing, and irrigation comprise the majority of the sediment inputs on the lower reaches of the stream.

An example of gully erosion on California Creek

Human manipulations, namely channel straightening, have occurred in the alluvial mid-valley of the drainage, also leading to stream incisement and sediment loading. While portions of the stream are highly incised, there are also stretches of over-widened stream from bank trampling but they are still unable to access their floodplain due to frequent de-watering.

 

Projects/Solutions:  

A scalloped bank on California Creek where cattle cross the stream.

Best management practices and potential projects include those that would reduce sediment loading, allow vegetation in the riparian zone to recover and reestablish itself, and reduce bank erosion. Examples include: fencing, off-stream watering, developing and implementing grazing management plans, and riparian vegetation planting.

Currently, California Creek is regularly de-watered during irrigation season. Improvements to irrigation timing and efficiency hold potential for addressing stream de-watering, temperature concerns, and riparian vegetation vitality. Sediment reduction projects in the California Creek subwatershed should focus on mitigating floodplain alterations caused by historical placer mining.  These projects include:

  • Stream channel/floodplain manipulation to increase stream sinuosity, restore inactive side channels, and allow natural channel evolution.
  • Reconnecting the stream to its floodplain or reconstructing floodplain to allow energy dissipation which would reduce bank erosion, increase shallow aquifer recharge, assist riparian vegetation recruitment, and allow sediment to deposit in the floodplain during high flow events (increase stream sediment transport function).