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Leona RiverPotential Loads and Sources forBacteria and Nitrates
Texas Institute for Applied Environmental ResearchStephenville, Texas
June 4, 2013
•Lead Agency -Texas Soil & Water Conservation Board
•Support provided byNueces River Authority
Texas A&M Dept Soil & Crop Sciences & Spatial Sciences Laboratory
Acknowledgements
Modeling to Evaluate Water Quality and Sources
• Load Duration Curves (LDCs)
• SELECT (Spatially Explicit Load Enrichment Calculation Tool)
Load Duration Curves (LDCs)
Purpose: • To define flow conditions under
which desired loads are exceeded• Define potential load reductions
Load Duration Curves
LDCs use the following:• Daily stream flow data• Allowable or desired concentration• Measured concentrations and flows
USGS 8204005TCEQ 12988/12989
USGS 8204250TCEQ 12987
USGS 8204500TCEQ 12985
Locations for Load Duration Curve Development
Load Duration Curves
Allowable or desired concentrationPrimary Contract Recreation Standard
E. coli 126 cfu/100 mL
General Use Screening Level Nitrate 1.95 mg/L
Load Duration Curves
Steps -1. Develop Flow Duration Curve (FDC)
(time history of daily flow data)
2. Calculate allowable loads(criterion or screening level)
3. Estimate measured loads(measured concentrations and flow)
4. Compare measured to allowable loads
Flow Duration Curves (FDCs)• Daily stream flows for a given time period
ranked highest to lowest
Flow ConditionPercent Time
Exceeded High Flows 0-10% Moist Conditions 10-40% Mid-Range Conditions 40-60% Dry Conditions 60-90% Low Flows 90-100%
Use of LDCs for Source Identification
Source Graphic: http://www.kdheks.gov/tmdl/basic.htm#dataThe Kansas Department of Health and Environment
High Flows Mid-Range
Dry Low Flows
Moist
Average Percent Reduction E. coli
NA indicates not applicable, because most low flows were zero flow.
Average Percent Reduction Nitrate
NA indicates not applicable, because most low flows were zero flow.
Potential Reductions Needs• Bacteria & Nitrate – primarily at higher flows associated
with rainfall-runoff • Bacteria – lower flows indicated near Batesville
• Nitrates– lower flows indicated near Divot
Load Duration Curve - Summary
SELECT (Spatially Explicit Load Enrichment Calculation Tool)
– Developed by Dept. of Biological and Agricultural Engineering and Spatial Sciences Laboratory at Texas A&M University by Dr. R. Karthikeyan, Dr. R. Srinivasan and others
Modeling Bacteria Sources
• Identifies POTENTIAL bacteria loadings by subwatershed
• Based on spatial data, such as:– Land use– Soils– Stream network– Animal density– Population information
SELECT
Spatial Science Laboratory Texas A&M University in College Station• Satellite imagery • Aerial photos• Ground control
points• Ground verification
• Population & Household Densities – Census data
• Livestock Densities– County Agricultural Statistics (USDA)
• Wildlife– Resource Experts (TPWD & others)
• Domestic & Feral Animals– Resource Experts (TPWD & others)
Input Data
• Wastewater Treatment Facilities– Uvalde– Batesville– US Fish & Wildlife Service National Fish
Hatchery• Concentrated Animal Feeding
Operations– Chaparral Cattle Feedlot (Uvalde)– Live Oak Feedlot (Batesville)
Permitted Facilities
CAFOsChaparral Cattle Feedlot south of Uvalde
(10,000 permitted head)Live Oak Feedlot southeast Batesville
(8,000 permitted head)
Input E. coli production rate 1E10 cfu/animal/day assuming “treatment” efficiency of 80%
Cattle #s in Leona Uvalde 5,516 Zavala 10,566 Frio 6,418
Input Fecal Production RateCattle 10E10 cfu/animal/day
Input Fecal Production RateCattle 10E10 cfu/animal/day
Cattle distributed on Grassland Herbaceous and Pasture/Hay
Cattle #s in Leona Uvalde 5,516 Zavala 10,566 Frio 6,418
Feral Hog #s in Leona 21,462
Input Fecal Production RateFeral Hogs 1.1E10 cfu/animal/day
Feral Hogs distributed on 100 meter buffer of stream in non-developed areas
Input Fecal Production RateSheep/Goats 1.2E10 cfu/animal/day
Sheep/Goats distributed on Grassland Herbaceous, Pasture/Hay, Shrubland & Woodland
Sheep/Goats #sin Leona Uvalde 8,055 Zavala 1,269 Frio 168
Deer #s in Leona 16.8/1,000 acres
Input Fecal Production RateDeer 3.5E8 cfu/animal/day
Deer distributed on Near-Riparian Forest, Shrubland & Woodland
Dog #s in Leona 1.6/household
Input Fecal Production RateDogs 5.0E9 cfu/animal/day
Homes in each subbasin based on 2010 Census Block Data
Masks out areas covered by public wastewater service areas
Homes in each subbasin based on 2010 Census Block Data
Uses NRCS Soils Data to define Septic Drainage Limitation
Class
Effluent Rate 10E6 cfu/100 mL with discharge of 60
gal/person/day for systems on soils with septic limitations
Urban Discharge
(MGD)Uvalde WWTF outfall #1 0.2604Uvalde WWTF outfall #2 0.6138Uvalde WWTF outfall #3 0.0558Batesville 0.184Fish Hatchery 0.8Effluent EC rate based on 126 cfu/100 ml
SELECT• Indicates potential
loadings based on a “worst case” scenario
• Highlight “hot spots” to consider for control efforts
• These are preliminary results open to stakeholder feedback
Contact Information
Nikki JacksonEmail: [email protected] Phone: 254.968.1920
Anne McFarlandEmail: [email protected] Phone: 254.968.9581
Questions?
Thank You
Anne McFarlandTexas Institute for Applied Environmental Research