input of all dredging in an equal time period. 



Quantitative correlations of species diversity depression with waste 

 water toxicity have been determined by previous studies in the San 

 Francisco Bay area (Kaiser Engineers Consortium, 1969, Allan Hancock 

 Foundation, 1965). These studies found a linear relationship between 

 the concentration of toxicity in the Bay waters and the reduction in 

 benthic species diversity. 



More recently, a study was made by the San Francisco District of the 

 Corps of Engineers (U. S. Army Engineer District, San Francisco, 1971), 

 for the purpose of determining the effects of disposal of dredge materials 

 on the marine environment, developing dredging procedures, and assessing 

 disposal sites. The development of alternatives that would mitigate 

 possible adverse effects or augment marine resources in the affected 

 area was considered. The preliminary study was confined to dredging 

 spoils from the Main Ship Channel, the first leg of the John F. Baldwin 

 and Stockton Ship Channel. Studies of the remaining parts of the John 

 F. Baldwin Ship Channel, Oakland Harbor, Richmond Harbor, Redwood Har- 

 bor and other areas, have not yet been reported. The study program in- 

 cluded sampling, testing, and analyzing the physical, biological, and 

 chemical characteristics of the Main Ship Channel and those of the dis- 

 posal site on the San Francisco Bar, south of the Main Channel, outside 

 the Bay. 



Based on the completed parts of the studies it was concluded that: 

 (a) the dredge spoil material from the Main Ship Channel leading into 

 the San Francisco Bay is not considered polluted by present EPA criteria, 

 with the exception of zinc which in two out of five instances exceeded 

 EPA limits; (b) insufficient sampling of water quality data could not 

 permit complete analysis of the impact of dredging and disposal operations 

 in the area, but preliminary data indicated water quality at the test 

 site to be within limits established by the California Regional Water 

 Quality Control Board; (c) benthic animals of the borrowing types, which 

 were observed on the Bar, appeared to be capable of surviving under some 

 sediment accumulation; (d) dispersion by strong currents of dredge 

 material dumped waters over the Bar does not appear to significantly 

 alter bottom conditions or result in excessive deposition of sediments. 

 In view of ever- changing, dynamic bottom conditions and the types of 

 organisms inhabiting the Bar, it was concluded that bottom organisms 

 would not likely suffer any harmful burial effects as a result of spoil 

 discharge on the Bar; and finally, (e) because of the active circulation 

 characteristics, unpolluted material disposed on the Bar would enter the 

 littoral regime, and might contribute beneficially to the nourishment of 

 eroding coastal beaches. 



Since July 1970, two additional studies of the problem of dredging 

 and spoil disposal were funded by the Corps of Engineers and were made 

 by the Environmental Protection Agency and the U. S. Geological Survey. 

 The EPA study includes environmental investigations on the effects of 

 channel opening in the periodically polluted section of San Joaquin River 



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