stations for production of electricity. Recent figures in Maryland indicate that 

 chlorine release to Bay water (assuming no degradation) is about 12 million kg/yr 

 (27 million lb/ yr) from sewage treatment plants and 1 million kg/yr (2.2 million 

 lb yr) from power generation (Davis and Middaugh, 1977). Perhaps 1 percent of this 

 becomes halogenated organic compounds and persists in the system. The toxicity of 

 chlorine and of chlorine-produced oxidants has been established for some Chesa- 

 peake species, and the larval stages are generally the most susceptible ( Bertine et al., 

 1980; Chesapeake Research Consortium, 1977; Davis and Middaugh, 1977; Roberts 

 et al.. 1979). 



Massive kills of four species offish in the James River in 1973 resulted in vigorous 

 cooperative studies and analyses by state agencies (Douglas, 1979; Virginia Marine 

 Resources Commission, 1 979). Chlorine and its derivatives were clearly implicated. 

 Operational improvements in treatment plants, dechlorination, and perhaps the use 

 of bromine chloride, an effective disinfectant of lower estuarine toxicity, are useful 

 in reducing mortalities — which were in fact lowered to acceptable levels (LeBlanc et 

 al., 1978; Douglas, 1979). A chlorination workshop in 1977 provided 16 summaries 

 of available knowledge of the fate and effects of chlorine, the problems and 

 techniques involved in analysis of chlorine and residual chemicals, uses in cooling 

 systems, bioassay of plants and animals, and the behavioral and physiological 

 responses of estuarine organisms (Block and Helz, 1977). 



Recently, concern for chlorine effects has again surfaced, and controversy over the 

 balancing of protection of public health versus injury to valuable estuarine species is 

 receiving fresh attention (Horton, 1980). A public conference titled "Chlorine 

 Bane or Benefit'.'" is scheduled for the spring of 1981. 



Herbicides have been used for agricultural purposes, especially in no-till practices, 

 in increasing quantities in the last decade. No-till practices, which reduce runoff but 

 require the use of herbicides, began about 1969, and by 1977 application of triazines 

 in the Bay region reached 1,500 to 15,000 tons, depending upon the estimator (Citi- 

 zens' Program for the Chesapeake Bay, 1978). A small percentage, on the order of 1.5 

 to 2.0 percent, may be carried off into water. Some reaches the estuary. In the same 

 period, submerged aquatic vegetation progressively declined in abundance over 

 much of the Chesapeake system — about 50 percent in the number of sites (among 

 625) that were vegetated in Maryland, and extensively in Virginia (Citizens' Program 

 for the Chesapeake Bay, 1978). The coincidence has been noted and argued 

 extensively (Cronin et al., 1977). An extensive summary of knowledge about such 

 vegetation in the Bay noted that these chemicals can injure such plants in laboratory 

 experiments, that the extent of damage in the Bay system is unknown, and that a 

 considerable number of other factors may affect submerged aquatic vegetation 

 (turbidity, salinity, fauna, temperature, sediments, chlorine, nutrients, boating, etc.) 

 (Stevenson and Confer, 1978). The Chesapeake Bay Program includes related 

 projects on (Wells et al., 1979; Davis. 1980): 



• Distribution of Submerged Vascular Plants in the Chesapeake Bay, Maryland — 



1978 and 1979 



• Distribution and Abundance of SAV in the Lower Chesapeake Bay, Virginia — 



1978 and 1979 



• Zostera marina: Biology, Preparation, and Impact of Herbicides 



• Submerged Aquatic Vegetation in the Chesapeake Bay: Its Role in the Bay Eco- 



system and Factors Leading to Its Decline 



• Assessment of the Potential Impact of Industrial Effluents on Submerged 



Aquatic Vegetation 



• Effects of Recreational Boating, Turbidity, and Sedimentation Rates in 



Relationship to Submerged Aquatic Vegetation 



• Factors Affecting and Importance of Submerged Aquatic Vegetation in Chesa- 



peake Bay (Wells et al.. 1979; Davis. 1980). 



There are also valuable projects on the functional roles of aquatic vegetation and 

 their use as habitats for important species. 



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