function can be restored. The next step in restoring 

 freshwater flow to the upper Nueces Delta should be 

 the implementation of a long-term (permanent) 

 diversion project. In the context of this future 

 scenario, the authors of this report present several 

 opportunities for enhanced project design and future 

 ecological studies. These recommendations were 

 developed based upon observ^ations gained from the 

 results of the demonstration project. 



OPPORTUNITIES FOR A 

 PERMANENT DIVERSION PROJECT 



From analysis of the hydrographic data collected during 

 the demonstration period, a permanent diversion 

 project could be designed that would produce 

 hydrographic benefits exceeding those of the 

 demonstration project. During the demonstration 

 period, the primary limitations of the total volume of 

 freshwater diverted during a given hydrographic event 

 were restrictions imposed by channel capacity and 

 channel obstructions. Widening some reaches of 

 Rincon Bayou in the upper delta that have significant 

 restrictions in channel capacity {e.g., the reach between 

 the Nueces Overflow Channel and the low water 

 crossing at the head of Rincon Bayou) would result in a 

 greater available cross-sectional area and lower 

 factional resistance. 



Also, if existing channel obstructions {e.g., the private 

 road crossing separating the upper and central Rincon 

 Bayou segments, and the remaining fill material in the 

 north end of the Rincon Overflow Channel) were 

 removed, diversion rates during events would improve 

 (Bureau of Reclamation 2000). Also, the amount of 

 water passing out of the delta back into the river 

 through the diversion channel(s) at the end of a given 

 hydrographic event would likely be reduced. Each of 

 these two recommendations would increase the 

 potential for freshwater diversions beyond that 

 provided by the demonstration project design. 



As with the short-term demonstration, a long-term 

 diversion project would have to address the issue of 

 voluntary landowner participation. This factor 

 prevented the continuation of the demonstration 



project. Although key landowners were wiUing to 

 consider easements that would have allowed project 

 features to remain in perpetuity, a price agreeable to all 

 parties was not able to be negotiated. 



OPPORTUNITIES FOR FURTHER 

 ECOLOGICAL STUDY 



Selection and Monitoring of 

 Indicator Species 



The use of one (or a few individual) species to reflect 

 the overall condition of an ecosystem is not a new 

 concept. For such indicator species to be useful in 

 applied research, they should have the following 

 characteristics: 1) they should direct attention to 

 qualities of their environment, 2) they should give an 

 indication that some environmental characteristic is 

 present, 3) they should express a generalization about 

 their environment, 4) their study should suggest a 

 cause, outcome or remedy, and 5) they should show a 

 need for action (Soule 1988). During the 

 demonstration period, benthic organisms were useful as 

 indicators of ecosystem productivity, particularly in 

 regards to the effects of freshwater inflow. 



Benthos 



Future monitoring of delta productivity should 

 consider the use of indicator benthic invertebrates. 

 These organisms are useful indicators because they are 

 relatively long-lived and sessile, so they integrate the 

 effects of freshwater inflow over appropriate temporal 

 and spatial scales. Changes in benthic biomass and 

 abundance indicate changes in secondary productivity, 

 and changes in benthic biodiversity are an important 

 indicator of habitat quality. Although the 

 demonstration project focused primarily on infauna 

 {i.e., animals living within sediments), an important 

 aspect of improving inflow conditions in the Nueces 

 Delta is restoring habitat functionality. This issue could 

 be assessed using epifauna {i.e., animals living on or 

 near the sediment surface) as well. Abundances of 

 epifaunal organisms (i?.^., shrimp, crabs, moUusks and 

 benthic feeding fish) would indicate habitat utilization. 



8-2 V Future Opportunities 



