the cahaba river watershed nutrient tmdl 2006 national monitoring conference san jose, ca 2006...
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The Cahaba River Watershed Nutrient TMDL
The Cahaba River Watershed Nutrient TMDL
2006 National Monitoring Conference
San Jose, CA
2006 National Monitoring Conference
San Jose, CA
Presented by: Chris L. JohnsonState of Alabama
Agenda for Today
• Characteristics of the Cahaba River• Nutrient Impacts to the Cahaba River• Summary of the Cahaba Nutrient TMDL
– Nutrient target development– Application of the target to Cahaba River– TMDL results and NPDES permit requirements– TMDL implementation strategy
• Current Status of Cahaba TMDL• Ongoing Initiatives
Characteristics of the Cahaba
River
• Drainage Area – 397 mi2
• Land Use/Cover – 50% forested, 37% urban, 7% agriculture
• Ridge & Valley Region– Sandstone Ridges w/ limestone,
dolomite/shale– Naturally low nutrient levels
• Multiple Uses – water supply, swimming, fishing, recreation
• Hydrology - Flashy • Lots of points sources
– 12 majors– 19 minors
JEFFERSONCOUNTY
SHELBYCOUNTY
BIBBCOUNTY
ST. CLAIRCOUNTY
Incorporated AreasCounty BoundariesStreams303(d) Listed SegmentsBibb Co. Hwy 24Shelby Co. Hwy 52US Hwy 280Interstate HighwaysLake PurdyUpper Cahaba River Basin
10 0 10 20 Miles
N
EW
SALABAMA
Shelby Co. 52
Bibb Co. 24
Cahaba River
Birmingham
Centreville
I-20
I-459I-65
I-59
US Hwy 280
Buck Creek
Lake Purdy
Location Map
Nutrient Impacts to the Cahaba River
N
EW
S
Cahaba River (36.9 miles)-Siltation-Other Habitat Alteration
Cahaba River (26.5 miles)-Nutrients-Siltation-Pathogens-Other Habitat Alteration
Cahaba River (24 miles)-Nutrients-Siltation-Other Habitat Alteration
StreamsLake PurdyUpper Cahaba River Basin303(d) Listed Cahaba River Segments
Cahaba River (17.4 miles)-Nutrients-Siltation
§303(d)Segments
* Currently Listed for Nutrients
WaterbodySegment ID
Miles Segment Location (downstream to
upstream)
Date Listed
01 17.4 Buck Creek to US280 1998
02 36.9 US280 to I59 2006
03 26.5 Shades Creek to Buck Creek
1996
04 24.0 ALHwy82 to Shades Creek
1998
What are the Nutrient Impacts?
• Tip for the Day! - Documenting high TP & TN Levels is not sufficient in/of itself!!
• Cahaba River– Aquatic life use is impaired by excessive nutrients:– Nuisance algal blooms (excess periphyton growth)– Dissolved oxygen violations– Huge daily swings in dissolved oxygen– Undesirable shifts in the native species of plants
and animals– Loss of Habitat
JEFFERSONCOUNTY
SHELBYCOUNTY
BIBBCOUNTY
ST. CLAIRCOUNTY
Incorporated AreasCounty BoundariesStreams303(d) Listed SegmentsBibb Co. Hwy 24Shelby Co. Hwy 52US Hwy 280Interstate HighwaysLake PurdyUpper Cahaba River Basin
10 0 10 20 Miles
N
EW
SALABAMA
Shelby Co. 52
Bibb Co. 24
Cahaba River
Birmingham
Centreville
I-20
I-459I-65
I-59
US Hwy 280
Buck Creek
Lake Purdy
Focused DO data analysis on the lower
segments
Shelby Co Highway 52 (S2)
• Downstream of Buck Creek
• Still highly entrenched
• Canopy present
• §303(d)-listed for nutrients, siltation, pathogens, and other habitat alteration
b
'W
'W
'W
'W
'W
'W 'W
'W
'W
'W
'W
'W
'W'W
'W
'W
'W
#S
Incorporated AreasCahaba River BasinStreamsLake Purdy303d-listed waters
b NCDC Weather Station'W NPDES Point Sources'W Industrial Discharge#S Withdrawal
10 0 10 20 Miles
N
EW
S
Bibb Co Highway 24 (S1)
• Downstream of Shades Creek
• Wide and flat
• No canopy
b
'W
'W
'W
'W
'W
'W 'W
'W
'W
'W
'W
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'W'W
'W
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'W
#S
Incorporated AreasCahaba River BasinStreamsLake Purdy303d-listed waters
b NCDC Weather Station'W NPDES Point Sources'W Industrial Discharge#S Withdrawal
10 0 10 20 Miles
N
EW
S
Day
Dis
solv
ed
Oxy
gen
(mg
/L)
So
lar
Rad
iatio
n(W
/m2)
Daily
Ave
rag
eF
low
(cfs
)
105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240 2450
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20 0
500
1000
1500
2000
2500 0
1000
2000
3000
4000
5000
6000
7000
8000
9000
Solar Radiation (W/m2)1999 Flows Daily Average Flow (cfs)S1-1999 Dissolved Oxygen (mg/L)S2-1999 Dissolved Oxygen (mg/L)
Sep 21999
Apr 151999
Cahaba River S1 versus S2 (1999)
Day
Dis
solv
ed
Oxy
gen
(mg
/L)
So
lar
Rad
iatio
n(W
/m2)
Daily
Ave
rag
eF
low
(cfs
)
195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 2255
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20 0
500
1000
1500
2000
2500 0
1000
2000
3000
4000
5000
6000
7000
8000
9000
Solar Radiation (W/m2)1999 Flows Daily Average Flow (cfs)S1-1999 Dissolved Oxygen (mg/L)S2-1999 Dissolved Oxygen (mg/L)
Aug 131999
Jul 141999
Cahaba River S1 versus S2 (Jul – Aug, 1999)
Nutrient Impacts-When and Where do These Impacts Occur?
• Downstream of “food” sources– WWTPs– Urban runoff
• During periods of low flow, low velocity, and high temperature.
• Areas where the river is wide, water is shallow, tree canopy is open and light is readily available.
Overview of the Cahaba River Nutrient TMDL
Why do we need nutrient targets?
• Numeric Nutrient Criteria for Rivers & Streams Not Currently Established
• Need Quantifiable Endpoints to Evaluate Condition of Waterbody in Regards to Meeting its Designated Use(s)
• Necessary for TMDL Development
Key Aspects of Nutrient Target Development for Cahaba River
• Consistent with EPA Guidance & Recommendations
• Uses a Reference Condition Approach• Scientifically Defensible• Uses Total Phosphorus (TP) as the
Controlling Nutrient • Fully Supports Designated Uses• Long-Term Monitoring Plan is Essential
Nutrient Target Cont’d
• ADEM and EPA Region 4 have collected, compiled & reviewed extensive resources to determine the nutrient target.– Multiple agencies have collected data within the Cahaba River
Watershed.– Chemical, physical and biological data and information.
• EPA Region 4 Conclusion:• Recommended range of 20 to 40 g/L total phosphorus
should prevent filamentous algae growth and be protective of designated uses.
ADEM Nutrient Target Approach for the Cahaba River
• Select Set of Least-Impacted Reference Streams.– ADEM reference stations with sufficient data,
– Same Level III Ecoregion (Ridge & Valley)
– Mixed land use,
– Low levels of measured periphyton, and
– Healthy habitat, macroinvertebrates, and fish communities
• Calculate the 75th percentile of growing season data.– For Ecoregion 67, Target = 35 µg/L TP
#S
#S
#S
#S
#S
#S
67
DRYC-2
DRYT-9
FRMB-8MAYB-1
HNMB-4
TCT-5
40 0 40 Miles
Level III EcoregionsPiedmont (45)Southeastern Plains (65)Ridge and Valley (67)Southwestern Appalachians (68)Interior Plateau (71)Southeastern Coastal Plain (75)
303(d) Listed Segments#S Ecoregion 67 Reference Sites
N
EW
S
ADEM Reference Stations in Ecoregion 67
Station Samples 11-digit HUC
Median TP
(μg/L)
Median TN
(μg/L) Stream Name Basin
DRYC-2 9 03150106240 29 279 Dry Cr (Calhoun Co.) Coosa
DRYT-9 8 03150106330 35 203 Dry Cr (Talladega Co.) Coosa
FRMB-8 11 03150202090 27 249 Fourmile Cr (Bibb Co.) Cahaba
HNMB-4 12 03160111070 31 304 Hendrick Mill Branch Black Warrior
MAYB-1 19 03150202080 21 267 Mayberry Cr Cahaba
TCT-5 11 03150106330 19 144 Talladega Cr Coosa
Growing Season Median, Maximum, Minimum, and 75th and 90th Percentile Total Phosphorus for ADEM Reference Sites in Ecoregion 67
Error bars indicate range (maximum and minimum).
0
10
20
30
40
50
60
70
80
90
DRYC-2 DRYT-9 FRMB-8 HNMB-4 MAYB-1 TCT-5 ALLDATA
To
tal
Ph
osp
ho
rus
(g
/L)
Median TP
75th Percentile
90th Percentile
TP Target
Ecoregion Reference Site Data
35 g/LTarget
Weaknesses with Current Approach
• Very Conservative!!!
• Not an “effects-based” target
• Reference watersheds are not on the same scale.
• Uncertainty remains– Cause and effect relationships are a mystery!!– How much algae is too much?
Nutrient Target Application
• Interpretation of target is key to ensure protection of the designated uses of the Cahaba River
• Spatial = 3 locations chosen to monitor instream conditions. – Roper Road (St. Clair County Road 10)– Bain’s Bridge (Old Montgomery Highway)– Shelby County Highway 52
• Temporal = Growing season median (multiple years) should not exceed TP target at these predetermined evaluation points– Growing season is defined as April-October– Study period evaluated: 1999-2001 growing seasons
Application of Target to Cahaba River:1999-2000 TP Concentrations
0
100
200
300
400
500
600
700
800
AboveTrussville
BelowTrussville
US 280 Caldwell MillRd
Hoover US 31 Bain's Bridge Shelby Hwy52
Piper Bridge
Med
ian
To
tal P
ho
sph
oru
s (u
g/l)
Median TP
TP Target (35 g/l)
'W
'W'W
'W
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'W
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'W
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'W
#·
#S
#S
#S
J EFFERSON CO
SHELBY CO
BIBB
Roper Rd
Old Montgomery Hwy
Shelby Co. Hwy 52
US HWY 280
Cahaba River BasinCounty BoundariesStreams303(d)-Listed Cahaba RiverLake PurdyUS Hwy 280
'W NPDES Small Point Sources'W NPDES Municipal Point Sources#· Water Supply Intake#S Instream Compliance Points
10 0 10 20 Miles
N
EW
S
Instream Evaluation Points
• Downstream of point sources and urban areas
• Upstream of known/potential periphyton “hot spots”
• Meeting a 35 µg/L target (GSM) at these 3 points mitigates nutrient impacts throughout Cahaba system.
0
100
200
300
400
500
600
700
800
AboveTrussville
BelowTrussville
US 280 Caldwell MillRd
Hoover US 31 Bain's Bridge Shelby Hwy52
Piper Bridge
Med
ian
To
tal P
ho
sph
oru
s (u
g/l)
Median TP
Instream Evaluation Points
EvaluationPoints
TP Target (35 g/l)
TMDL Implementation Strategy• Phase 1: NPDES permit revisions required by 2010 (based
on assumed TMDL Approval date of 2005)– Majors (>1.0 MGD)-monthly avg. limit not to exceed TP = 0.4 mg/L– Minors (<1.0 MGD)-monthly avg. limit not to exceed TP = 2.0 mg/L
• Phase 2: NPDES permit revisions required by 2015– Major (>1.0 MGD)-monthly avg. limit not to exceed TP = 0.2 mg/L– Minors (<1.0 MGD)-monthly avg. limit not to exceed TP = 0.5 mg/L– Urban areas achieve 25% reduction in TP (1999-01’ baseline)
• Phase 3: NPDES permit revisions required by 2020– Major (>1.0 MGD) monthly avg. limit not to exceed TP = 0.043 mg/L– Minors (<1.0 MGD)-monthly avg. limit not to exceed TP = 0.3 mg/L– Urban areas achieve 65% reduction in TP (1999-01’ baseline)– Cahaba River meets instream target of 35 µg/L at evaluation points
Comparison of WWTP Effluent TP and Proposed TP Limits
0.035
0.043
0.100
0.170
0.200
0.214
0.240
0.285
0.400
1.5
1.8
5.1
0.01 0.10 1.00 10.00
Tualatin (OR) Durham WWTP (2003)
TMDL PHASE 3 MAJOR WWTPs
TMDL PHASE 3 MS4 DISCHARGE
Atlanta RM Clayton WWTP (2003-2004)
PHASE 2 Major WWTPs
PHASE 2 MS4 DISCHARGE
Major Atlanta WWTPs (2003-2004)
EXISTING MS4 DISCHARGE
PHASE 1 Major WWTPs
Jefferson Co. Cahaba WWTP (2003-2004)
Hoover Riverchase WWTP (2003-2004)
Birmingham Riverview WWTP (2001)
Avg. Effluent Total Phosphorus (mg/L)
Implementation Strategy to Reduce Total Phosphorus Loads
• Reducing WWTP loads:– NPDES permits for reduced effluent TP concentrations
• Reducing MS4/urban loads:– NPDES MS4 permittees are expected to meet a 65%
reduction using a BMP approach.
• Reducing nonpoint source loads:– Clean Water Partnership and Upper Cahaba Watershed
Consortium– Land use planning considerations for watershed
protection
TMDL Implementation Strategyfor NPDES Permits
• Permit compliance schedule:– will be reviewed on an individual facility basis;– must achieve the WLA “as soon as possible”;– will establish interim targets on a case-specific basis; and– will be re-evaluated every permit cycle based on available
data and information.
• However, the compliance schedule cannot continue indefinitely; other options (e.g., variance) may be necessary down the road.
• Permitting Mechanism:– “Watershed Permit” for TP for Cahaba point sources
similar to Neuse River permit for nitrogen is being considered.
Current Status of Cahaba River TMDL
• Comment period closed January 2005.
• Wrapping up response to public comments.
• Minor revisions to the TMDL Report are underway.
• Expected to submit to EPA for approval very soon!!!
Questions or Comments?