441 



tremely complex in luiture. Many factors interact to give them their natural 

 characteristics. Because of this inherent complexity, they are difficult to under- 

 stand and manipulate intelligently. 

 Complex user requirements 



Because of their proximity and accessibility, the coastal waters are the most 

 used and exploitable of all the waters of the world ocean. Many users wish to 

 take their "cuts." Sometimes these uses are in real or apparent conflict with each 

 other and some uses are temi)orarily or permanently damasing to the resources. 

 The .Tames and Rappahannock rivers are excellent illustrations of the innate 

 complexities of our coastal waters. In their downriver, tidal reaches, both are 

 stratilied systems with heavier salt water from the Bay on the bottom and lighter 

 fresh water from the upriver and shoreline drainage areas in the upper layer. 

 The salty bottom water flow upstream even though the fresh flow is downstream. 

 This creates problems as in the case of the lower James where it is certain that 

 a change in the depth of the river bottom will alter the velocity of the upstream 

 flow, change the depth of the lower layer and allow waters of greater salinity to 

 intrude further upriver than before. Though these changes are certain the extent 

 is uncertain. Also unknown are the possible repercussions these physical changes, 

 certain to occur, will have on the oyster fishery. It is know that successful larval 

 survival and spat setting and survival depend upon the upstream current and the 

 upstream limits of salinity. This has been the chief natural resource problem in 

 the James River development program up until now. 



Changes in the volume rate of flow in the upper, fresher layer are also im- 

 portant in determining success of marine organisms. As a consequence, dams 

 which may be operated in such a way as to change the flow may change the 

 salinity regime and affect survival of oysters, clams and other useful invertebrates 

 by allowing salinity-dependent predators and survivors onto productive bottoms. 

 This prospect is being considered in the plans of the Salem Church Dam on the 

 Rappahannock River. 



Engineermg projects 



Engineering projects such as channel enlargement and realignment and dam 

 construction on our estuaries are numerous and increasing. Each year sees dozens 

 of small and large channel pro.iects : Over 400 small and large dams are proposed 

 for the Potomac system alone for the next several years. 



Reservoir construction and operation are not the only engineering diflSeulties 

 that marine resources must face. Also involved are fill and drainage of salt 

 marshes, filling and erosion of sorelines and waterways, bridge and island con- 

 struction and siltation resulting from engineering projects. Engineering activities 

 may pose severe threats to marine resources. Conversely, they may also be 

 planned and operated so as to enhance those resources, e.g., reservoir operation 

 to reduce pollution and improve water quality or actually enhance oyster and 

 clam survival and growth, as the Institute and the Corps are attempting to do 

 with the Salem Church project. It is possible, by proper planning to minimize 

 adverse effects. 



Contamination 



Increasing populations and industrialization along our tidal rivers will be 

 inevitably accompanied toy increasing contamination — this cannot be escaped at 

 this time. The James and Rappahannock are, even now, being polluted (more 

 than necessary). The problem is one of degree. Pollution can and must be con- 

 trolled and minimized. Difficulties in setting allowable tolerances for marine 

 water quality are encountered because we lack the detailed information concern- 

 ing tJie physiological responses of the organisms necessary to set such limits. 



Shoreline Use 



Virginia's shorelines are rapidly being occupied. Potential shoreline for indus- 

 trial, residential and recreational use are diminishing. In many areas the most 

 valuable shores are already gone. It is important that those remaining be hus- 

 banded wisely. We must be esepcially careful that the urge to grow and indus- 

 trialize does not eliminate natural areas important to the ecology of the estuaries, 

 the survival of important organisms, the recreational activities of man and 

 aesthetic uses. Only the bare minimum of degradation must be allowed. For this 

 reason plans for the use of this land should and must be developed well ahead of 

 pressures. 



26-563— 69— pt. 1 29 



