patterns through the diversion channel, at the Rincon Bayou Station, 08211503, at the culverts above station C, 

 station D and the culvert at this site, stations E and F and when available stations 50 and 51 at the mouth of 

 Rincon Bayou in Nueces Bay. Observations at Station 08211503 verified with the gage data for this station 

 indicate that the water exchange reported from this gage is accurate. The following is an example of the staff 

 readings and the gage read-out for 6 observations. 



DATE TIME GAGE STAFF 



1.14 



2.15 



No Data 



1.57 

 1.23 

 1.69 



The daily flow regime through the Nueces River Diversion Channel into Rincon Bayou is now established. The 

 connection between the channel and upper Rincon Bayou where the ranch road crosses has resulted to a 

 narrow ditch where water exchanged takes place. The ditch has vegetation growing up in both banks and 

 seems to be maintained by almost daily tidal exchange into and back out of upper Rincon Bayou. Although no 

 diel observations were made, the wet banks near low areas suggest tidal inundations moves water onto the flats 

 occasionally. There is a split of tidal flow in the upper Rincon with tidal movement coming and going from 

 both Nueces Bay and the Nueces River, resulting in higher salinity estuarine water from the bay meeting with 

 lower salinity Nueces River water from the diversion chaimel in the upper Rincon Bayou. This exchange has 

 helped alleviate the stagnated high salinity conditions observed when upper Rincon Bayou was a dead-end. 

 High salinity conditions can still be expected during droughts and extreme low tides especially dimng the 

 summer. The extent of water exchange in Rincon Bayou depends on the magnitude of the tidal of freshwater 

 inflow event. A major event results in complete flushing and mixing of the system all the way to the bay while 

 normal daily tidal movement may only move enough water to maintain some exchange with upper Rincon 

 Bayou which is important. 



Rincon Bayou Seasonal Observations 



Hydrographic and environmental conditions at Rincon Bayou are dependent on annual tidal cycles and seasonal 

 climatic conditions. Local weather events can dramatically effect these conditions, i.e. droughts, floods and 

 tropical disturbances. 



The typical annual cycle based on annual quarters: 



January usually results in low winter tides and cool to cold temperatures. These conditions don't typically result 

 in high evaporation and high salinities. 



April conditions are associated with spring high tides which disperse brown shrimp post larvae and crab larvae 

 throughout the delta and niu-sery areas. Many drum and redfish migrate into the area to feed on the growing 

 shrimp population. 



July often has periods of very low tides, low rainfall, associated with high temperatures and high evaporation. 

 Rincon Bayou stations often dry up or the water becomes hypersahne. 



October is the transition for summer to fall. The tides may be high especially with tropical storm activity and 

 flooding may occur modifying typical high salinity conditions from summer. At the control stations A & B 

 which are often dry in July and August the fall rainfall results in the germination and growth of Ruppia beds 

 which are an important food source for waterfowl. 



Appendix G ^ G-5 



