Area 19 (South end of the Big Lake Mapping Unit):
East-west canals were cut by North American Land Company steam dredges prior to1900, which resulted in breaching of the Calcasieu Lake rim. This area was farmedfor rice; freshwater from inside Calcasieu Lake was used to irrigate rice fields fromaround 1875 until 1910. Saltwater and tidal invasion (salinities up to 30 ppt)associated with the deepening of the CSC in the 1940s, coupled with the loss offreshwater inflow from the Pleistocene terrace due to construction of the GIWW, contributed to marsh loss.
Area 20 (Sweet/Willow Lakes Unit):
This area was a solid marsh until marsh buggies were used in the 1950s to mash down the marsh to create duck ponds. Around 1925-28, the levee encompassing the brinepit in Area 20A broke and saltwater from the brine pit killed much of this freshmarsh. The use of brine pits and the pumping of produced water into adjacentmarshes were abandoned in this area in 1948 when injection wells began to be usedfor brine disposal. There are still about 45 producing oil wells in this area. Erosion of the north bank of the GIWW has resulted in a direct hydrologic connection with both Willow Lake and Sweet Lake. The CWPPRA Sweet Lake/Willow LakeShore Protection Project is addressing this problem. The Coast 2050 Region 4 Regional Planning Team indicated that land loss in this area was due to altered hydrology, flooding, and storms (LCWCRTF/WRCA 1998).
Area 20A (Sweet/Willow Lakes Unit: Section 36):
This area was owned by North American Land and Sweet Lake Land & Oil and leased to Union Oil Company of California at the turn of the century. It was utilizedas a produced-water disposal pit for the oil withdrawn from the Sweet Lake Unit inthe 1920s. It is now about 4 ft deep because of levee deterioration.
Area 21 (Cameron-Creole Watershed Unit):
Loss of the historical saw grass marsh in this area is attributable to saltwater intrusionfrom the CSC in the 1950s. The whole area began dying after cuts were madethrough the Calcasieu River channel mouth bar in the late 1930s and early 1940s. Marsh deterioration occurred through progressive dying of the standing saw grass. When Hurricane Audrey hit in 1957, the saw grass system was alreadydead or dying, and the hurricane’s storm surge cleared away the dead and deteriorated saw grassstands. Much of the saw grass was killed by the discharge of produced water fromlocalized oil wells.
Area 22 (Cameron-Creole Watershed Unit): Saltwater intrusion from the Creole Canal and Calcasieu Lake through the CalcasieuShip Channel killed some of the marsh vegetation, and tidal action eroded the highlyorganic soils in this area.
These findings reveal that, in most areas, a combination of human-induced hydrologic changes, sometimes accompanied by severe storm events, has resulted in virtually all of the habitat changes and land losses in the Calcasieu-Sabine Basin. The hydrologic alteration that has had the most impact is the CSC, a major avenue for saltwater and tidal intrusion, which has caused extremely severe marsh losses. Secondary causes of landscape change include oil- and gas-related activities such as canal construction, incidentalimpoundment, and produced-water discharge; historical natural resource managementpractices that are nolonger employed; agriculture through intentional impoundment of the marsh for wildlife management and cattle grazing; and nutria herbivory and trapping canal
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