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

Assessment Bacteria

Assessment Nitrates

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

FDC Leona River near Uvalde1970 – 2010

LDC E. coli - Leona River near Uvalde

Criterion126 cfu/100 mL

Potential Reductions

% Reduction = (Allowable – Measured) Measured * 100

Averaged by Flow Category

LDC E. coli Leona River near Uvalde

Average Percent Reduction E. coli

NA indicates not applicable, because most low flows were zero flow.

LDC Nitrates Leona River near DivotE. coli data 1972 – 2012

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

Questions??s

Load Duration Curves

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

98%

99.8%

2%

68%

95%

32%

5%

4%11%

84%

80%

17%2%

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 does not yet handle• Exotics• Small wildlife (birds, raccoons, etc)

Sources not included

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: njackson@tiaer.tarleton.eduOffice Phone: 254.968.1920

Anne McFarlandEmail: mcfarla@tiaer.tarleton.eduOffice Phone: 254.968.9581

Questions?

Thank You

Anne McFarlandTexas Institute for Applied Environmental Research

mcfarla@tiaer.tarleton.edu254.968.9581