Download Load Duration Curves (LDCs)

Leona River
Potential Loads and Sources for
Bacteria and Nitrates
Texas Institute for Applied Environmental Research
Stephenville, Texas
June 4, 2013
Acknowledgements
• Lead Agency Texas Soil & Water
Conservation Board
• Support provided by
Nueces River Authority
Texas A&M Dept Soil &
Crop Sciences & Spatial
Sciences Laboratory
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
Locations for
Load Duration Curve
Development
USGS 8204005
TCEQ 12988/12989
USGS 8204250
TCEQ 12987
USGS 8204500
TCEQ 12985
Load Duration Curves
Allowable or desired concentration
Primary 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 Condition
High Flows
Moist Conditions
Mid-Range Conditions
Dry Conditions
Low Flows
Percent Time
Exceeded
0-10%
10-40%
40-60%
60-90%
90-100%
Use of LDCs for Source Identification
High Flows
Moist
Source Graphic: http://www.kdheks.gov/tmdl/basic.htm#data
The Kansas Department of Health and Environment
Mid- Dry Low
Range
Flows
FDC Leona River near Uvalde
1970 – 2010
LDC E. coli - Leona River near Uvalde
Criterion
126 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 Divot
E. coli data 1972 – 2012
Average Percent Reduction Nitrate
NA indicates not applicable, because most low flows were zero flow.
Load Duration Curve - Summary
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 Curves
Questions
??s
Modeling Bacteria Sources
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
SELECT
• Identifies POTENTIAL bacteria
loadings by subwatershed
• Based on spatial data, such as:
– Land use
– Soils
– Stream network
– Animal density
– Population information
Spatial Science Laboratory
Texas A&M University in
College Station
• Satellite imagery
• Aerial photos
• Ground control
points
• Ground verification
Input Data
• Population & Household Densities
– Census data
• Livestock Densities
– County Agricultural Statistics (USDA)
• Wildlife
– Resource Experts (TPWD & others)
• Domestic & Feral Animals
– Resource Experts (TPWD & others)
Permitted Facilities
• Wastewater Treatment Facilities
– Uvalde
– Batesville
– US Fish & Wildlife Service National Fish
Hatchery
• Concentrated Animal Feeding
Operations
– Chaparral Cattle Feedlot (Uvalde)
– Live Oak Feedlot (Batesville)
17%
2%
2%
80%
11%
4%
98%
84%
99.8%
32%
68%
5%
95%
CAFOs
Chaparral 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 Rate
Cattle 10E10 cfu/animal/day
Cattle #s in Leona
Uvalde 5,516
Zavala 10,566
Frio
6,418
Cattle distributed on Grassland
Herbaceous and Pasture/Hay
Input Fecal Production Rate
Cattle 10E10 cfu/animal/day
Feral Hog #s in Leona
21,462
Feral Hogs distributed on 100 meter
buffer of stream in non-developed areas
Input Fecal Production Rate
Feral Hogs 1.1E10 cfu/animal/day
Sheep/Goats #s
in Leona
Uvalde 8,055
Zavala 1,269
Frio
168
Sheep/Goats distributed on Grassland
Herbaceous, Pasture/Hay, Shrubland &
Woodland
Input Fecal Production Rate
Sheep/Goats 1.2E10 cfu/animal/day
Deer #s in Leona
16.8/1,000 acres
Deer distributed on Near-Riparian
Forest, Shrubland & Woodland
Input Fecal Production Rate
Deer 3.5E8 cfu/animal/day
Dog #s in Leona
1.6/household
Input Fecal Production Rate
Dogs 5.0E9 cfu/animal/day
Homes in each subbasin based
on 2010 Census Block Data
Homes in each subbasin based
on 2010 Census Block Data
Masks out areas covered by public wastewater
service areas
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
Discharge
Urban
(MGD)
Uvalde WWTF outfall #1
0.2604
Uvalde WWTF outfall #2
0.6138
Uvalde WWTF outfall #3
0.0558
Batesville
0.184
Fish Hatchery
0.8
Effluent EC rate based on 126 cfu/100 ml
Sources not included
SELECT does not yet handle
• Exotics
• Small wildlife (birds, raccoons, etc)
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 Jackson
Email: [email protected]
Office Phone: 254.968.1920
Anne McFarland
Email: [email protected]
Office Phone: 254.968.9581
Questions?
Thank You
Anne McFarland
Texas Institute for Applied Environmental Research
[email protected]
254.968.9581