EFFECTS OF DRAWDOWN AND WATER MANAGEMENT 

 ON A SERIOUSLY ERODED MARSH 



Bruce Lehto 



District Conservationist 



Soil Conservation Service 



1400 Highway 14 

 Lake Charles, LA 70601 



and 



Jeff Murphy 



1200 Paris Street 



Lake Charles, LA 70601 



ABSTRACT 



The occurrence of submergent and emergent plant species was recorded during October 1986, 

 October 1987, and May 1988 in a severely eroded 541-ha marsh located adjacent to Black Lake 

 in Cameron Parish, LA. Measurements from 1940 aerial photographs show 99% emergent 

 vegetation and 1% open water. Measurements from 1983 aerial photographs show 2% emergent 

 vegetation and 98% open water. O'Neil (1949) classified the area as fresh and intermediate marsh. 

 The dominant vegetation in the 1940's was Jamaica sawgrass (Cladium jamaicenese). 



A system of levees and two guillotine-type structures prevent water exchange with the 

 surrounding marsh and Black Lake. Rainfall is the sole source of water. 



A pump was used to effect a drawdown in the summer of 1986. Prior to the drawdown, the 

 emergent plant species recorded were marshhay cordgrass (Spartina patens), glasswort (Salicornia 

 sp.), seashore paspalum (Paspalum vaginatum), smooth cordgrass (Spartina alterniflora) and black 

 needlerush (Juncus roemeranus). No submergent species were recorded. 



A record of emergent species occurring in October 1986 was the same as prior to the drawdown. 

 No submergent aquatics were recorded. 



A pump was also used to effect a drawdown again in the summer of 1987. A record of 

 emergent species occurring in October 1987 included all species recorded in October 1986 plus 

 coast bacopa (Bacopa caroliniana), dwarf spikesedge (Eleocharis parvula), sprangletop (Leptochloa 

 fascicularis), and cattail (Typha sp.). Submergent species recorded was widgeongrass (Ruppia 

 maritima). 



A pump was again used to effect a drawdown in the spring of 1988. A record of emergent 

 species occurring in May 1988 included all species recorded in October 1987 plus saltmarsh bulrush 

 (Scirpus robustus) and bulrush (Scirpus validus). Widgeongrass was the only submergent species 

 recorded. 



INTRODUCTION 



Deterioration of the marshes in the Black Lake area of Cameron Parish has resulted in a 

 dramatic loss of vegetated areas to open water. An 81% reduction of vegetated areas occurred 



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