1. Bays in Peril: A Natural Inflow Approach for Texas Estuaries
Norman D. Johns, PhD, National Wildlife Federation Warren Pulich, PhD, Texas State University

2. The Natural Flow Paradigm
“managing an ecosystem within its range of natural variability is an appropriate path to maintaining diverse, resilient, productive, and healthy systems” (Swanson et al. 1993)
general
Maintain “full natural range of variation of hydrologic regimes...” measured by – timing, frequency, duration, and rate of change of key biologically significant hydro events (Richter et al. 1997)
flows

3. 3 step

7. Corpus Christi Caller-Times, Sept. 24, 2003

8. 3 step

9. High Variability is Inherent
Galveston Bay Measured Freshwater Inflows
High Variability is Inherent

11. Shrimp & Freshwater Inflows

12. NWF’s Ecologically Relevant Inflow Criteria
productivity maintenance- 4 month spring/early summer freshwater inflow pulse (a.k.a. “Freshete”) 1.

13. Oysters & Freshwater Inflows

14. NWF’s Ecologically Relevant Inflow Criteria
productivity maintenance- 4 month spring/early summer freshwater inflow pulse (a.k.a. “Freshete”) 1.
drought analysis – 6 consecutive months very low-inflows, between Mar. – Oct. 2.

15. WAM = Hydrology Tool
- predict inflows
- differing scenarios: Natural Conditions Current Use Full Water Rights Levels of reuse
- monthly results

19. Assessing Springtime Freshwater Pulse

20. Degree of Alteration = 60%

23. National Wildlife Federation Analysis of Estuary Inflows
productivity maintenance- spring Freshete
drought analysis - population survival

24. NWF’s Low Flow Assessment
[ MinQsal ]

25. Degree of Alteration > 500%(high)

27. Next Steps Application to Regional Planning Process
Refinement of Criteria (time window, benchmark volumes based on natural stats.)
Further examine ecological relevance of criteria