A PILOT STUDY FOR ASSESSING FRESHWATER FLOW IMPACTS TO LOUISIANA ESTUARIES

A PILOT STUDY FOR ASSESSING FRESHWATER FLOW IMPACTS TO LOUISIANA ESTUARIES Ryan Clark, Melissa Baustian, Eric White, Yushi Wang, Andrea Jerabek, and Harris Bienn Louisiana Water Conference March 27, 2018

WATER MANAGEMENT IN LOUISIANA But, Louisiana has too much water Mississippi River Bayous Seafood Rainfall Floods 2

WATER MANAGEMENT IN LOUISIANA But, Louisiana has too much water Mississippi River Bayous Seafood Rainfall Floods Not all water is the same Drought Local impacts Climate change Environmental flow needs coastal & instream 3

PROJECT GOALS Sustainability: A balance between use and supply that causes no further impairment to water resources, and maintains or improves the current health of these systems Develop a Framework Surface & groundwater Using available data Useful to decision makers LA Water Code Sustainability in light of present and projected uses 4

PROJECT GOALS Establishing a standardized set of measures: evaluating water supply across LA Setting baseline water budgets - groundwater and surface water Create modular framework Tested in areas with sufficient data and existing tools Capable of use in sparser data areas More refined tools and data can be substituted 5

REVIEW EXISTING FRAMEWORKS - LOUISIANA 6

REVIEW EXISTING FRAMEWORKS OTHER STATES 7

REVIEW EXISTING FRAMEWORKS 8

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FRAMEWORK APPLICATION Apply framework to pilot study area (SWLA) Estimates of surface and groundwater supply and usage Projections of future supply and usage Apply framework to NWLA and SELA study areas 10

SELECTED STUDY AREAS SWLA - East Chicot Aquifer Area NWLA - Carrizo-Wilcox Aquifer Area SELA - West Southern Hills Aquifer Area Chosen for: Data availability Mix of uses Existing supply/ demand imbalances Cover different parts of state/ unique issues 11

WATER BALANCE RESULTS Hydrologic Unit Total Water Inflow (acrefeet/year) Total Water Outflow (acrefeet/year) Unallocated Water (acrefeet/year) Percent Change Bayou Teche 5,639,321 3,034,498 2,604,823 +46.2% Vermilion 4,385,187 2,367,734 2,017,454 +46.0% Mermentau 3,409,647 1,967,600 1,442,046 +42.3% Headwaters Mermentau 6,031,189 3,257,310 2,773,880 +46.0% Total 19,465,344 10,627,142 8,838,203 +45.4% 12

WATER BALANCE RESULTS Hydrologic Unit Total Water Inflow (acrefeet/year) Total Water Outflow (acrefeet/year) Unallocated Water (acrefeet/year) Percent Change Bayou Teche 5,473,672 2,801,733 2,671,939 +48.8% Vermilion 4,304,848 2,198,761 2,106,087 +48.9% Mermentau 3,350,916 1,633,156 1,717,760 +51.3% Headwaters Mermentau 5,913,295 3,009,574 2,903,721 +49.1% Total 19,042,731 9,643,224 9,399,507 +49.4% 13

WATER BALANCE RESULTS Hydrologic Unit Total Water Inflow (acrefeet/year) Total Water Outflow (acrefeet/year) Unallocated Water (acrefeet/year) Percent Change Bayou Teche 165,649 232,765-67,116-40.5% Vermilion 80,339 168,973-88,633-110.3% Mermentau 58,731 334,444-275,714-469.5% Headwaters Mermentau 117,894 247,736-129,841-110.1% Total 422,613 983,918-561,304-132.8% 14

SUMMARY Created framework for assessment of water supply & demand usable statewide Tested on areas with data available, and existing studies for comparison Can be applied to other areas of the state with sparser data and fewer existing studies Modular, improvable/customizable with new data and tools 15

PATH FORWARD Collaborative & Coordinated with other research Resolution Spatial HUC12 and finer Temporal - Annual means seasonal scale, including seasonality of demand Refine tools Groundwater Availability Models Refine data Minimum ecological flow estimation (estuarine) 16

FINDING THE RIGHT FLOW Modeling current and future river needs to maintain fish and freshwater forest in the Pontchartrain Basin Melissa M. Baustian, F. Ryan Clark, Andrea S. Jerabek, Yushi Wang, Eric D. White

OUTLINE Introduction and Background Freshwater inflow and study area Research objective Methods Integrated Compartment Model (ICM) Model simulations Results Vegetated habitat Habitat suitability indices Discussion and Conclusions Management implications 18

FRESHWATER INFLOW Sustains ecosystems balance of plants and animals Affects ecological functions (i.e., regulation of salinity, delivery of nutrients and sediments) (Alber, 2002; Baron et al., 2002) Without a sufficient input of freshwater, freshwater habitats will be unable to provide key ecosystem services that support coastal communities, such as fisheries, flood protection, and recreation (Shaffer et al., 2016, 2009). 19

STUDY AREA: LAKE PONTCHARTRAIN BASIN, LA 20

LAKE MAUREPAS AND MAUREPAS SWAMP 21

OBJECTIVES Use Integrated Compartment Model (ICM) to: Simulate Amite riverine flow based on various climate change and restoration scenarios Test the sensitivity of outputs to inflow variations Spatial and temporal distribution 1. Vegetation types (e.g., fresh forest, intermediate marsh, open water) 2. Habitat Suitability Indices (HSI) (e.g., spotted seatrout, bay anchovy, and largemouth bass) 22

2017 MP INTEGRATED COMPARTMENT MODEL (ICM) ICM-Hydro: Hydrologic model Water surface elevation Water level variability Salinity Suspended sediment Habitat Suitability Indices (HSI) Temperature Salinity % land (Hijuelos et al., 2017) ICM-Morph: Wetland morphology model Long term landscape evolution, relative elevation model (Couvillion et al., 2013) ICM-LAVegMod: Vegetation model Species coverage (Visser and Duke-Sylvester, 2017) (Visser et al., 2013) 23

MODEL COMPARTMENTS FS = French Settlement LB = Land Bridge LM = Lake Maurepas MS = Maurepas Swamp Footer 24

MODEL SIMULATIONS (6) 50 year (2017 2067) simulations Medium environmental scenario (Meselhe et al., 2017) Normal rainfall Climate change rainfall Adjusted Amite river hydrograph (i.e., flashier ) Draft Coastal Master Plan projects 25

SIMULATION DETAILS Draft Coastal Master Plan Projects Union Freshwater Diversion Manchac Landbridge Diversion East Maurepas Diversion Lake Pontchartrain Barrier 26

Climate Change Rainfall Normal Rainfall MODEL SIMULATIONS Without Restoration With Restoration Base Base_CD Comite diversion Base_MP Draft MP2017 projects Base_CC Base_CC_MP Draft MP2017 projects Base_CC_MP_AD Draft MP2017 projects + hypothetical diversion 27

OUTLINE Introduction and Background Freshwater inflow and the study area Research objective Methods Integrated Compartment Model (ICM) Model simulations Results Vegetated habitat Habitat suitability indices Discussion and Conclusions Management implications 28

TEMPORAL VEGETATION TRENDS With Restoration (Coastal Master Plan Projects) Base_MP Normal rainfall Base_CC_MP Climate change rainfall Without Restoration Base Normal rainfall Base_CC Climate change rainfall Baustian et al. In Press 29

BALD CYPRESS 50-YEAR DIFFERENCE MAP Base_CC Without Restoration Base_CC Climate change rainfall Base_CC_MP With Restoration (Coastal Master Plan Projects) Base_CC_MP Climate change rainfall Baustian et al. 2017 30

HYPOTHETICAL DIVERSION TEMPORAL ECOLOGICAL EFFECTS Hypothetical Freshwater Diversion With hypothetical diversion Base_CC_MP_AD Without hypothetical diversion Base_CC_MP Baustian et al. In Press 31

RESTORATION PROJECT HSI EFFECTS With Restoration (Coastal Master Plan Projects) Base_MP Normal rainfall Base_CC_MP Climate change rainfall Without Restoration Base Normal rainfall Base_CC Climate change rainfall Baustian et al. In Press *no effects were seen for flood control 32 project or hypothetical diversion

OUTLINE Introduction and Background Freshwater inflow and the study area Research objective Methods Integrated Compartment Model (ICM) Model simulations Results Environmental parameter Ecological parameters Vegetated habitat and HSI s Discussion and Conclusions Management implications 33

Conclusions KEY POINTS Major driver of ecosystem change in the Lake Maurepas area is relative sea level rise - the combination of rising seas and sinking land (Keddy et al. 2007) Fresh forest in Maurepas Swamp decrease significantly under all future climate and relative sea level rise simulations but decrease less when there are restoration projects 34

Conclusions WHAT S NEXT Method can show general trends and sensitivity of indicators to variations in freshwater flow Work with resource experts to refine methods and establish target ecological flow regimes Apply methods to other rivers/estuaries across LA coast 35

THANK YOU @TheH2OInstitute @theh2oinstitute Please contact Ryan Clark at rclark@thewaterinstitute.org 1110 S. River Road, SUITE 200 BATON ROUGE, LA 70802 (225) 448-2813 WWW.THEWATERINSTITUTE.ORG

THANK YOU @TheH2OInstitute @theh2oinstitute Please contact Ryan Clark at rclark@thewaterinstitute.org 1110 S. River Road, SUITE 200 BATON ROUGE, LA 70802 (225) 448-2813 WWW.THEWATERINSTITUTE.ORG

ACKNOWLEDGEMENTS LA DNR Office of Conservation LA Coastal Protection & Restoration Authority Technical Coordination Team David Borrok Charles Demas Gary Hanson John Lovelace Pierre Sargent

PILOT STUDY AREA: SWLA East Chicot Aquifer Area Surface water basins: Bayou Teche Vermilion River Mermentau River mix of demand uses Agriculture (including rice) Livestock Industry Urban/rural domestic Coastal 39

PILOT STUDY AREA: SWLA Hydrologic Unit Number of Households Estimated Freshwater Demand (acrefeet/year) Number of Public Supply Systems Population Served Number of Domestic Water Wells Bayou 81,241 36,401 56 199,533 2,107 Teche Vermilion 135,446 60,688 112 446,824 9,428 Mermentau Headwaters 46,004 20,612 30 124,201 2,209 Mermentau 21,704 9,725 16 44,294 4,271 40

USGS GROUNDWATER TOOLBOX 41

USGS GROUNDWATER TOOLBOX Estimate components of streamflow: base flow runoff Also used to estimate: Precipitation Groundwater recharge (near surface) Evapotranspiration Adapted to include: Deep aquifer recharge from precipitation infiltration in recharge zone, and from vertical leakage 42

CONSTRAINTS & QUALITY IMPACTS SWLA study area surface water balance, including impacts of coastal salinity on water usability Hydrologic Unit Total Water Inflow (acrefeet/year) Reduced Water Inflow (acrefeet/year) Unallocated Water (acrefeet/year) Percent Change Bayou Teche 5,473,672 5,364,198 109,474-2.0% Vermilion 4,304,848 1,954,401 2,350,447-54.6% Mermentau Headwaters 3,350,916 3,350,915 1 0.0% Mermentau 5,913,295 2,980,300 2,932,995-49.6% Total 19,042,731 13,649,81 4 5,392,917-28.3% 43

CONSTRAINTS & QUALITY IMPACTS SWLA study area summary of overall water balance, including impacts of 10% impaired quality on surface water usability Hydrologic Unit Total Water Inflow (acrefeet/year) Reduced Water Inflow (acrefeet/year) Unallocated Water (acrefeet/year) Percent Change Bayou Teche 5,639,321 5,091,954 547,367-10.7% Vermilion 4,385,187 3,954,702 430,485-10.9% Mermentau 3,409,647 3,074,555 335,092-10.9% Headwaters Mermentau 6,031,190 5,439,860 591,330-10.9% Total 19,465,34 5 17,561,071 1,904,273-10.8% 44

FUTURE PROJECTIONS Impacts of population growth and urbanization on water supply and demand 45

FUTURE PROJECTIONS 46

FUTURE PROJECTIONS SWLA total water balance change under future urbanization scenario Hydrologic Unit Change in Groundwater Input (acre-feet/year) % Change in Groundwater Input Change in Surface Water Input (acrefeet/year) % Change in Surface Water Input Bayou Teche -1,798-1.1% 32,743 +0.6% Vermilion -70-0.1% 63,892 +1.5% Mermentau Headwaters -105-0.2% 36,439 +1.1% Mermentau -63-0.1% 9,104 +0.2% SWLA total water balance change under population growth scenario Hydrologic Unit Change in Groundwater Output (acrefeet/year) % Change in Groundwater Output Change in Surface Water Output (acrefeet/year) % Change in Surface Water Output Bayou Teche 945 +0.6% 34 <0.1% Vermilion 4,420 +5.5% 40 <0.1% Mermentau Headwaters -49-0.1% 0 0.0% Mermentau 119 +0.1% 0 0.0% 47

FRESHWATER INFLOW Amite River, 2016

OUTLINE Introduction and Background Freshwater inflow and the study area Research objective Methods Integrated Compartment Model (ICM) Model simulations Results Vegetated habitat Habitat suitability indices Discussion and Conclusions Management implications 49

SIMULATION DETAILS Proposed Comite River Diversion Flood control project in the Amite watershed Divert Comite River west into the Mississippi River upstream of Baton Rouge via 12 mile diversion channel 50 Louisiana Department of Transport and Development

FLOOD CONTROL PROJECT TEMPORAL ECOLOGICAL EFFECTS FS LM Without Diversion Base With Comite Diversion Base_CD French Settlement Lake Maurepas Baustian et al. In Press 51