Water temperatures during the study ranged from 1 1 " to 29 " C. 

 with the salinity ranging from 1. 7%e at the station in the upper river to 30. 3%o 

 at the mouth. During calm weather, surface turbulence at the seaward edge 

 of the salt-water wedge in the river was readily observed. Salinity readings 

 on the bottom indicate that the leading edge of the wedge was often several 

 thousand feet upstream of the surface manifestation. Parkers Cut provides 

 a connection between West Matagorda Bay and the Colorado River, and cur- 

 rents induced by ebb and flood tides are sometimes very swift in this area. 

 Parkers Cut, however, does not seem to appreciably affect the salinity in 

 West Matagorda Bay. At present, the salinity seems to be relatively stable, 

 probably due to passes opened on the Gulf side by Hurricane Carla. These 

 passes ^vill probably be closed eventually by the surf and subsequent silting 

 action, eliminating the exchange of water between the Gulf and bay. (See 

 figure. ) 



The average scilinity in both West Matagorda and East Matagorda 

 Bays was identical (25%o), but the range was greater in the former (17. 3%o 

 to 31. 2%o) than in the latter (17. 5%o to 28. l%o). There are two cuts between 

 the Gulf Intracoastal Waterway and West Matagorda Bay. These cuts are a 

 source of lower salinity water (average, 20%o) flowing into West Matagorda 

 Bay from the waterway. In East Matagorda Bay, there are three cuts be- 

 tween the waterway and bay. Live Oak Bayou and Caney Creek flow into the 

 waterway and through their respective cuts into East Matagorda Bay. These 

 two cuts are at the extreme eastern end of the bay and opposite Brown Cedar 

 Cut. It is possible that these waters flow through Brovm Cedar Cut and into 

 the Gulf. The third cut. Old Gulf Cut, is located about midway, opening 

 from the waterway into the bay. The source of fresh water in these bays is 

 very limited, the main source coming through precipitation and mixing of 

 the Colorado River water with the water in the canal. During June, at the 

 close of the study and the beginning of the warm weather, the salinity in 

 these bays approached 30%o. Probably as the weather became nnilder and 

 evaporation increased, it rose even higher. If the flow of fresh water in the 

 Colorado River is reduced, the salt-water wedge will move farther up the 

 river and into the Gulf Intracoastal Waterway. This would bring the bays to 

 yearlong sea-water conditions and decrease their value as nursery areas for 

 many of our marine forms. Tentatively, it would appear that regulation of 

 the fresh-water discharge from any impoundment upstream would be desir- 

 able, especially during periods of low rainfall and high salinity and during 

 the months when the bays serve to rear juvenile forms. A diversion channel 

 from the river into the bays might be helpful in maintaining suitable bay hab- 

 itat and would prevent loss of fresh water into the Gulf- 

 Preliminary analysis of the data indicates that the three most abun- 

 dant finfish taken in the trawl samples were the Atlantic croaker, the spot, 

 and the bay anchovy. The croaker was the most abundant fish taken, averag- 

 ing 58 fish per tow with modal length increasing from 20 to 60 mm. by late 

 June. The spot was second in abundance with an average catch of 15 fish per 

 tow and modal length increasing from 35 to 60 mm. 



71 



