The J. D. Murphree Wildlife Management Area, 

 located immediately south of the Port Arthur city 

 limits, was established in 1958. Aside from maintain- 

 ing a high quality marsh that is desirable to wintering 

 waterfowl, refuge personnel are also concerned with 

 developing marsh management techniques that will 

 aid marshland property owners in the management of 

 their own holdings. Hunting and fishing are allowed 

 on the 3,404 ha (8,4 11 a) of brackish and freshwater 

 marshes, which are only accessible by boat. The first 

 trapping program is scheduled to go into operation 

 during the 1 978-79 trapping season (David S. Lobpries, 

 Texas Parks and Wildlife Department, letter dated 

 8 August 1978). Oil and gas exploration is allowed 

 and must conform to strict guidelines set by refuge 

 personnel. Presently, no active oil or gas wells are on 

 the area. 



Anahuac National Wildlife Refuge, established in 

 1963, is located in the East Bay Basin. The 3,981 ha 

 (9,837 a) of coastal wetlands is bounded on the east 

 by Oyster Bayou, on the south by East Bay, and is 

 situated inland about three miles from the Gulf. The 

 refuge is managed primarily for migratory and winter- 

 ing waterfowl, although the endangered American 

 alligator and red wolf are also a major part of the 

 management program (U.S. Department of the In- 

 terior 1976). Controlled marsh burning is employed 

 for goose management and managed cattle grazing is 

 allowed on some refuge lands on a year-round basis. 

 Hunting and trapping are not permitted. Oil and gas 

 exploration and production activities are allowed but 

 are controlled by the refuge manager. Seismic opera- 

 tions are generally prohibited during the period from 

 November through February when wintering water- 

 fowl are present. 



Sea RimStateParkconsistsof6,117ha(15,115 a) 

 of beach and marshland in Jefferson County, 16 km 

 (10 mi) west of Sabine Pass, Texas. The area is 

 managed to preserve coastal estuaries and wetlands 

 and to provide recreational activities associated with 

 the Gulf beach (Texas Department of Parks and 

 Wildlife 1978). Specific marshland units are managed 

 for wintering waterfowl. Public hunting of waterfowl 

 is allowed on specified areas, but trapping is not 

 permitted. Oil and gas exploration and production 

 activities are allowed and are monitored by park 

 persoimel. 



4.7.4 MANAGEMENT FOR ECONOMIC RETURN 



A fmal type of management objective is to receive 

 an economic return. Individual and corporate land 

 holders usually must justify their investment in terms 

 of economic returns and they manage their holdings 

 to maximize this. In the Chenier Plain this usually 

 means extensive development for oil, gas, sulfur, and 

 salt extraction. One land management practice is to 

 construct a low levee along exposed shorelines of 

 lakes and larger bayous to prevent erosion of wetlands 

 to open water. This is done because mineral rights of 

 land that has eroded to open water revert to State 

 ownership. 



Income is also derived from leasing of wetlands 

 for cattle grazing, and hunting and trapping. Land- 

 owners often alter wetlands by constructing cattle 

 walks and mud-boat ditches, and by burning vegeta- 

 tion to enliance the features for which the land is 

 being leased. 



4.7.5 USE OF WEIRS IN WETLAND MANAGE- 

 MENT 



A weir is a submerged, low-sill dam placed in a 

 natural marsh tidal channel to prevent complete 

 drainage of ponds and tidal channels landward of the 

 structure. It may be a solid, single level dam or it may 

 have a stop-log structure that allows the sill depth to 

 vary. The sill or stop-log gate is usually placed no less 

 than 15 cm (6 in) below marsh surface elevation. 

 However, the specific sill setting varies with the size 

 of channel and area affected by the weir (Chabreck 

 1960). That is, if the affected area of wetland is large 

 relative to the cross-sectional area of the drainage 

 channel, the sill should be slightly lower than 6 in 

 (15 cm). 



Effects on Drainage and Water Level Fluctua- 

 tions. Weirs prevent complete drainage of wetlands at 

 low tide. Chabreck (1968b) determined that at a water 

 level of 0.3 m (1.0 ft) below mean sea level (MSL) 

 only 2.4% of weired pond bottoms en Rockefeller 

 National Wildlife Refuge were exposed as compared 

 to 84% of non-weired pond bottoms. Mean annual 

 water level behind these weirs was 0.12 m (0.4 ft) 

 higher than that for unaltered ponds. In a separate 

 study Herke (1968) found that weirs in coastal 

 Louisiana increased the area and duration of flooding. 



Effects on Water Salinity and Turbidity. Weirs re- 

 tain fresh rainwater in the marsh and thereby decrease 

 water salinity. During periods of drought, weirs retard 

 the intrusion of saltwater intowetlands. Chabreck and 

 Hoffpauir (1962) found that average water salinity 

 and turbidity were less than 10% lower behind weirs 

 than in nonweired areas. Wengert (1972) found that 

 weirs reduced the range of sahnities from 1.5 to 

 12.1 °/oo in nonweired areas to 2.0 to 4.8°/oo in weired 

 areas. 



Effects on Vegetation. Secondary effects of weirs 

 on the abundance and relative distribution of plant 

 species may be striking. Chabreck (1968b) reported 

 that weired areas had four times more aquatic vegeta- 

 tion than nonweired areas. Over a nine-year period, 

 spikerush increased and blackrush decreased in 

 weired areas, a change not noted in similar nonweired 

 areas. Herke (1968) also found that weirs stimulated 

 the growth of rooted aquatics. 



Effects on Movements of Aquatic Organisms. 



Weirs constructed in tidal channels restrict movements 

 of fishes and crustaceans into and out of wetland 

 areas. Herke (1971) found that weirs delayed recruit- 

 ment of organisms, especially spot and shrimp which 

 are associated with the bottom of channels; and 

 delayed emigration of other bottom species and some 

 surface species. Wengert (1972) concluded that weirs 

 may decrease the total number of brown shrimp using 

 the marsh as a nursery. 



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