TWCA - Galveston, TX June 19, 2015

1. June 21, 2013
Methods to promote freshwater
inflow to East Matagorda Bay

2. 2
Problem Statement
Elevated salinity and
Reduced Circulation

3. 3
What are we addressing?
- What amount of water could provide benefits?
- Where to divert the water?
- How to convey the water?
- What are rough costs?
Senate Bill 3 BBASC

4. 4
Conveyance Alternative?
Live Oak Creek,
Lake Austin tributary
≈ ½ mile

5. 5
Conveyance Alternative?
Lake Austin
Natural conveyance or
Pipeline/siphon

6. 6
Simplest option to infuse fresher water
3 miles
2 miles

7. 7
Another option during hypersaline
periods
< ½ mile

8. 8
Possible transmission pathways
Scenario 1
Scenario 2
D1
R2
R3
D2
Scenario 3
R1
R4
Scenario 4
Scenario 5
Scenario 6
D3
D5
D4
D6
Scenario 7

9. 9
Salinity Goals
- Reduce extended periods of
salinity greater than 30 ppt
- Macrobenthos (Palmer et al.)
- Oysters – 2 year average (MBHE)

10. 10
Salinity Goals
- Promote “Fair” salinity ranges
during particular months (MBHE)
- 20-23 ppt
- Atlantic Croaker (Jan-Jun)
- Gulf Menhaden (Apr-Aug)
- 20-25 ppt
- White Shrimp (Jul-Nov)
- Blue Crab (Feb-Jun)
- 30-32 ppt
- Brown Shrimp (Apr-Jul)

11. 11
Salinity Habitat Interface Tool
- Maps showing focus area (Hab
output and Salinity output)
- EMB 1/6
- Lake Austin?

12. 12
East Matagorda Bay

13. 13
Salinity

14. 14
Salinity
%
Rank
97pctl
88pctl
63pctl
44pctl
22pctl
05pctl
37% of days above 30 ppt
56% of days above 25 ppt

15. 15
Salinity
%
Rank
97pctl
88pctl
63pctl
44pctl
22pctl
05pctl
15 months 12m 17m 17m 17m
14 months
6m 11m 10m
12m

16. 16
Salinity
%
Rank
97pctl
88pctl
63pctl
44pctl
22pctl
05pctl
+2.5 ppt per month

17. 17
MBHE Salinity Model
- Animation

18. 18
East Matagorda Bay

19. 19
Salinity
%
Rank
97pctl
88pctl
63pctl
44pctl
22pctl
05pctl16,250 acft
273 cfs
30 days
5 months
30ppt Sep 1
30ppt Feb 6
33ppt Mar 17
Estimated
benefit: 3-5
months

20. 20
Summary
- 16,250 ac-ft of freshwater
- Positive impact
- 25% of EMB
- Three to five months

21. 21
Next steps: refinement
- Environmental benefits
- Timing and amount
- Cost (capital and O&M)
- Salinity of source water
- Freshwater flow available
- Permitting
- Summary
- Recommendations

22. 22
More next steps

23. 23
We welcome your input!
- Colorado/Lavaca BBASC
- Texas Water Development Board
- Meadows Center for Water and the Environment
- US Army Corps of Engineers
- Harte Research Institute
- Other Stakeholders…
Barney Austin
baustin@aquastrategies.com
Tel: (512) 826-2604