7 Discussion and 

 Recommendations 



56 



Management of the Mouth of the Colorado River 



As discussed above, the principal management problem at the MOCR is 

 caused by the inadequate size of the impoundment basin and its inefficiency in 

 retaining sediments. The response of SWG to date has been to increase the 

 frequency of the dredging schedule to approximately yearly. This is an 

 effective strategy, but other strategies may be more cost-effective and should be 

 considered. 



Total dredging costs may be decreased if the impoundment basin is 

 enlarged. There is some, but not a great deal of, area available between the 

 two jetties to enlarge the surface area of the impoundment basin. One 

 possibility would be to widen the basin to include the navigation channel within 

 it. Surveys show that the impoundment basin fills from the weir side first, so 

 the channel portion should be the last to fill. When the basin fills, it would 

 shoal the navigation channel, but that happens now. The larger basin volimie 

 would delay the shoaling time. Surveys show that in the present configuration, 

 the channel occasionally migrates and runs through the impoundment basin. 



Another possibility is to extend the basin landward so that it encroaches on 

 the portion of the beach that is inside the northeast jetty. This is a logical 

 location to increase the impoundment basin size because the basin filled 

 somewhat more rapidly at its shoreward end (Table 9). However, there are 

 safety concerns for swimmers associated with locating a deep dropoff next to 

 shore. There is also a little room to enlarge the basin along its seaward edge. 



The impoundment basin could also be somewhat deepened. This would not 

 only provide greater storage capacity, but should also improve its efficiency at 

 retaining sediments, at least shortly after dredging. Doubling the depth would 

 only increase the volume by about 75 percent due to the effect of the 1:5 side 

 slopes, so the best alternative may be to increase both the depth and the surface 

 area. 



Chapter 7 Discussion and Recommendations 



