Davis Pond River Diversion Project: Pre- and Post-Diversion Trends for Salinity Intrusion and Nutrient Removal

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1 Davis Pond River Diversion Project: Pre- and Post-Diversion Trends for Salinity Intrusion and Nutrient Removal Andrew Stoddard Chuck Villarubia Silong Lu Christopher Wallen Erol Karadogan CEER 2014 New Orleans, LA

2 Outline Louisiana Nutrient Management Strategy Davis Pond Diversion Data Sources and Methodology Pre- and Post-Diversion Trends Removal Efficiency Summary and Recommendations

3 Nutrient Management Strategy Davis Pond Improve management of Nonpoint Sources (BMPs, Incentives) Improve management of Point Sources (Monitoring, TMDLs, Permits, Enforcement) Leverage capacity of river diversions to reduce nutrient load to Gulf of Mexico

Davis Pond Freshwater Max Capacity: 10,650 cfs 9,300 acres Ponding Area Fully operational in 2007 Diversion Diversion authorized by Flood Control Act of 1965 Modified by

4 Davis Pond Freshwater Max Capacity: 10,650 cfs 9,300 acres Ponding Area Fully operational in 2007 Diversion Diversion authorized by Flood Control Act of 1965 Modified by Water Resources Development Act (WRDA, 1974, 1986, 1996, 2007) Constructed by USACE, Located ~15 miles upstream of New Orleans St. Charles Parish, near River Mile 118

Davis Pond Diversion Objectives Davis Pond River Diversion Reintroduce river flow of water, nutrients, sediments to coastal wetlands of Barataria Basin

5 Davis Pond Diversion Objectives Davis Pond River Diversion Reintroduce river flow of water, nutrients, sediments to coastal wetlands of Barataria Basin Reduce marsh loss; enhance marsh vegetation Improve fish and wildlife productivity Control salinity intrusion Removal of nutrients Removal of sediments

Performance Analysis of Diversion Jun-Nov: high biological productivity; operations based on 5 ppt salinity target in mid-basin River: Low/High Diversion:

6 Performance Analysis of Diversion Jun-Nov: high biological productivity; operations based on 5 ppt salinity target in mid-basin River: Low/High Diversion: Low/High Pre- Diversion: ( ) Post-Diversion ( ) Data Sources: USACE, USGS, WQPORTAL, CPRA, NOAA NODC Salinity intrusion Nutrient removal Sediment removal

7 Mississippi River and Diversion Median Flow (Jun-Nov) River: Low/High Diversion: Low/High Mississippi River, Davis Pond, Tarbert Landing 325,000 cfs 1,260 cfs Pre-Diversion 2 Cases Post-Diversion 2x2 Cases

8 Salinity

9 Salinity, River Flow/Low Lake Cataouatche Lake Salvador Little Lake Grand Bayou Barataria Pass 20 m isobath

10 Salinity, River Flow/High Lake Cataouatche Lake Salvador Little Lake Grand Bayou Barataria Pass 20 m isobath

11 Salinity, River Flow/Low Range for oysters 5-15 ppt

12 Salinity, Grand Bayou, 5 ppt Line N=12 N=409 N=675 N=363 N=721 N=704 River(Low) Pre-Diversion (1999,2000) River(High) Pre-Diversion (1997,1998,2001,2002)

13 Nutrients

14 NO3NO2, River Flow/Low Lake Cataouatche Lake Salvador Little Lake Grand Bayou Barataria Pass 20 m isobath

15 NO3NO2, River Flow/High Lake Cataouatche Lake Salvador Little Lake Grand Bayou Barataria Pass 20 m isobath

16 TOTAL-N, River Flow/Low Lake Salvador Little Lake Grand Bayou Barataria Pass 20 m isobath Lake Cataouatche

17 TOTAL-N, River Flow/High Lake Cataouatche Lake Salvador Little Lake Grand Bayou Barataria Pass 20 m isobath

18 Removal Efficiency

19 Summary

20 Summary & Recommendations Salinity Intrusion Diversion is most effective at reducing salinity near 5 ppt line at low river flow. Little effect of diversion at high river flow Little effect of diversion near 15 ppt line. Salinity controlled by river and Gulf of Mexico Removal Efficiency: Low diversion flow achieves higher removal efficiency for Nitrogen and TSS Confounding effects of physical forcing (e.g., wind, rain, storm events, river flow; Gulf circulation) make it difficult to isolate effect of diversion on mid-basin salinity Recommendation: Develop methodology to separate out effects of diversion and physical forcing in Barataria Basin on salinity during May-December higher diversion period

21 Questions? Andy Stoddard

23 Slides in Back Pocket

24 Sediments (TSS)

25 TSS, River Flow/Low Lake Cataouatche Lake Salvador Little Lake Grand Bayou Barataria Pass 20 m isobath

26 TSS, River Flow/High Lake Cataouatche Lake Salvador Little Lake Grand Bayou Barataria Pass 20 m isobath

27 TOTAL-P, River Flow/Low Lake Cataouatche Lake Salvador Little Lake Grand Bayou Barataria Pass 20 m isobath

28 TOTAL-P, River Flow/High Lake Cataouatche Lake Salvador Little Lake Grand Bayou Barataria Pass 20 m isobath

29 PO4T, River Flow/Low Lake Cataouatche Lake Salvador Little Lake Grand Bayou Barataria Pass 20 m isobath

30 PO4T, River Flow/High Lake Cataouatche Lake Salvador Little Lake Grand Bayou Barataria Pass 20 m isobath

31 Salinity, Wilkinson Canal

32 Salinity, Wilkinson Canal N=12 N=2 N=16 N=22 N=8 N=5 River(Low) Pre-Diversion (1999,2000) River(High) Pre-Diversion (1997,1998,2001,2002)

33 Salinity, Lac des Allemandes

34 Salinity, Lac des Allemandes N=6 N=2 N=16 N=14 N=11 N=5 River(Low) Pre-Diversion (1999,2000) River(High) Pre-Diversion (1997,1998,2001,2002)

35 Monthly Salinity, 5 ppt Line Grand Bayou 5 ppt 15 ppt

36 SALINITY-NO3NO2, River/High Salinity Mixing Diagram Davis Pond and Barataria Basin Strong sink for NO3NO2

37 Salinity, Barataria Bay, 15 ppt Line N=0 N=368 N=546 N=167 N=646 N=577 River(Low) Pre-Diversion (no data, 1999,2000) River(High) Pre-Diversion (1997,1998,2001,2002)

38 SALINITY-NO3NO2, River Flow/Low Salinity Mixing Diagram Davis Pond and Barataria Basin Strong sink for NO3NO2 Denitrification key process