The effect of mining gravel from a high-water channel on the scenic 

 quality of an area is minimal if the disturbance is restricted to the chan- 

 nel. If banks are destroyed the effect would be more significant. Since the 

 high-water channel is active only part of the year re-establishment of 

 pre-existing conditions will require a longer time. Formation of pits in 

 high-water channels would have effects similar to those described in the 

 section on Type of Gravel Removal. 



Abandoned Channel. Abandoned channels carry water only during major 

 flood events. Normally, these channels are considered to be dry during most 

 years. Since they represent old river channels they usually contain reason- 

 ably large quantities of gravel, depending on the type of river with which 

 they are associated. Only two of the sites studied were located on an aban- 

 doned channel. Prospect Creek and West Fork Tolovana River, both in meander- 

 ing systems. Abandoned channels are common in this type of floodplain be- 

 cause of the formation of cutoffs that result from the fluvial processes 

 of meandering channels. 



Location of material sites in abandoned channels causes little problem 

 with regard to changes in river hydrology and hydraulics because the sites 

 are separated from active flow. Where pits are dug in abandoned channels and 

 are connected to the active channel, flow can be diverted through the site 

 during high flows. The magnitude and duration of this change is dependent on 

 the nature of the connection between the material site and the channel and 

 the integrity of the undisturbed buffer zone separating the site from the 

 active channel. Where the once-abandoned channel carries water annually 

 during high-flow stages, the effects to the floodplain would be similar to 

 those described for sites in high-water channels. 



Where an abandoned channel is scraped and the water table is not 

 reached, water quality does not become a problem. Where pits become flooded, 

 the water quality would be different than that occurring in the active 

 channel, as is discussed in the section on pits. 



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