Paper 16 



The highest runoff measured at the mouth of Chesapeake Pay 

 (35G/C00 cu ft/sec) for any month since data were first recorded 

 in 1950 occurred in June 1972 as a result of Hurricane Agnesr and 

 because of it the annual mean for that year also was the highest 

 on record (about 130/000 cu ft/secx Appendix 16.1). The second 

 highest annual mean (IIS/OOC cu ft/sec)/ although not monthly 

 peak/ was in 1975/ associated with Hurricane Eloise in September; 

 the rest of that year was essentially normal. Mean flow in 

 October 1976 (179/900 cu ft/sec) exceeded that of September 1975 

 due entirely to e xt r at r op i ca I frontal activity. Despite the dry 

 months of spring/ the annual -nean flow in 1976 (&4/40C cu ft/sec) 

 was the sixth highest of the ?5 years of record. Runoff 

 decreased in November and was average in December. 



Runoff in the Delaware Bay and Hudson River (Fig. 16.1) 

 paralleled that in the Chesapeake due to the same climatic 

 conditions during the year. The December flow dropped in the 

 Delaware and Hudson Rivers as the onset of the cold winter of 

 1976-77 locked up precipitation in snow and ice. Long-term iiean 

 monthly runoff figures were not obtained for the Hudson River/ 

 and the 1976 data are provisional. The annual average of the 

 data set is 20/100 cu ft/sec over the period of record. 



Runoff affects estuarine and offshore fishes and shellfishes by 

 varying the salinity/ turbidity/ dissolved oxygen/ and 

 stratification of their environment. Early warming in the spring 

 of 1976 was associated with high runoff very early in the year. 

 This accentuated the early onset of stratification in the near 

 shore waters and suppressed oxygenation two months earlier than 

 usual. The normal summer biological depletion of dissolved 

 oxygen led to anoxic conditions and the subsequent fish kill in 

 July (Armstrong/ Paper 17). 



282 



