154 



approached the value found in shelf water generally. South of 

 the boil, although there was a decrease in concentration due 

 to dilution, minor maxima occurred at 6,000 and 9,000 feet. 

 The maximum values recorded within 3,000 feet of the boil are 

 23 )ig-a/L for silicate-silicon, 10 ^g-a/L for phosphate- 

 phosphorus, 6.5 ug-a/L for nitrate-nitrogen, and 68 ^g-a/L 

 for ammonia-nitrogen. In comparison with the Orange County 

 and Whites Point outfalls, Hyperion had the highest ammonia 

 value, the lowest nitrate value, with intermediate phosphate 

 and silicate concentrations. The oxygen concentration of the 

 surface water was low in the boil, but to the north and the 

 south it approached saturation within a few thousand feet. 

 On both days large tongues of supersaturated water (up to a 

 maximum value of 33% above the saturated value) were found in 

 the intermediate depths and at the surface. The large increase 

 in oxygen content above saturation values is normally attri- 

 buted to phytoplankton; however, vertical net hauls in the 

 surrounding area showed low plankton counts c 



With the exception of one or two pockets of low oxygen at 

 intermediate depth (ranging from approximately 40 to 50% of 

 the saturated value) the area, with the exception of the boil, 

 appears to be well oxygenated. Generally, the average oxygen 

 values at Hyperion are higher than those of Orange County or 

 Whites Point. An average value of 5.02 ml/L for both days was 

 found in the surface waters of the boil, implying that there 

 is an adequate amount of oxygen to meet the present oxidation 

 requirements of the effluent. 



