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

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'W

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#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

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'W

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#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

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20 0

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2500 0

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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

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2500 0

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7000

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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

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#·

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#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?