O 80 



- Dnll'D Id 



:|liiillliU 



158 60 66 70 74 



O 80' 



I I AQUATIC PLANTS 

 i; '|;| EMERGENT ANNUALS 

 ^M EMERGENT PERENNIALS 



MANAGEMENT 

 EVENTS 



1955-LEVEES BUILT 



METAL FLAP -GATE 

 CULVERTS 

 INSTALLED 



FLAP-GATE 

 CULVERTS LFAKING 



CONCRETE VARIABLE 

 CREST REVERSIBLE 



MANAGEMENT 

 EVENTS 



LEVEE REPAIRS 



WEST SIDE 



SOME FLAP-GATE 



CULVERTS 



PLUGGED 



FLAP-GATE STRUCTURES 

 i 

 ALL FLAP-GATE 

 CULVERTS REMOVED 



SEPT 1965 SEVERE 



MARSH BURN FOLLOWED 



BY HIGH SALINE TIDES 



CAUSED MARSH LOSS 



O 80- 



M 



^iufliuil 



MANAGEMENT 

 EVENTS 



iUMil 



1 



1965- LEVEES 

 CONSTRUCTED 



METAL FLAP-GATE 

 CULVERTS 

 INSTALLED 



VEAR 



FmP- GATE 

 CULVERTS LEAKING 



WOODEN BOX FLAP- 

 GATES INSTALLED 



MANAGEMENT 

 EVENTS 



CONCRETE VARIABLE 

 CREST REVERSIBLE 



LEVEE REPAIRS - 



EASTSIOE 



SOME FLAP-GATE 



CULVERTS PLUGGED 



FLAP GATE STRUCTURES' 



ALL FLAP-GATE CULVERTS 



REMOVED. WOODEN BOX 



FLAP-GATE CULVERTS 



PLUGGED 



VEAR 



METAL FLAP-GATE CULVERTS 



MAINTAINED AS 



PERMANTLV 



FLOODED 



FRESHWATER 

 IMPOUNDMENT 



BEGAN SPRING AND 

 SUMMER DRAW-DOWN 



DROUGHT FLOODED 



IN SUMMER FOR 



MOTTLED DUCK 



NESTING 



DOUBLE DIVERGENT . 



PUMPING UNIT 



Figure 74. The percentage of different types of vegetation 

 Rockefeller State Wildlife Refuge (Wicker et al . 1983). 



in impoundments in the 



from the effect of the associated dense 

 network of canals and spoil banks, but the 

 density of marsh grass culms and average 

 height was lower than in control areas (R. 

 E. Turner; pers. comm.). 



Amphipods, total crustaceans, and 

 total benthic organisms were reduced 50 

 percent compared to non-oilfield control 

 areas (Lindstedt 1978). Killifish 



abundance was substantially less in oil- 

 field marsh ponds than at control sites, 

 although not statistically so because of 

 the large confidence limits. However, the 

 fecundity of Fundulus grandis in oilfield 

 marshes was significantly lower than at 

 control sites, especially the condition 



index of females 61-80 mm long (May 1977). 

 It is apparent that we need to know much 

 more about the effects of chronic 

 low-level oilspills. 



From a management point of view, water 

 pollution is a good example of the need to 

 manage on many different levels. Water 

 quality of the Mississippi River must be 

 improved. This is a problem national in 

 scope because of the river's enormous 

 watershed. 



The control of urban runoff in the 

 delta itself is a regional problem that 

 affects marshes and estuaries in the New 

 Orleans area more than other delta 



97 



