Nutrient TMDL for the

Cahaba River Watershed

A joint proposal by

ADEM and EPA Region 4

Chris JohnsonWater Quality Branch

October 13, 2005

Outline• Overview of Nutrient Impacts to the Cahaba

River• Summary of the Cahaba River Nutrient TMDL

– Nutrient Target Development– Application of Target to Cahaba River– TMDL Results and NPDES Permit Requirements– TMDL Implementation Strategy

• Public Participation Process• Future Activities

Nutrient Impacts to the Cahaba River

§303(d) Listed Segments

Waterbody Name

Miles Designated Uses Causes of Impairment Sources §303(d) List

Segment Location

(Downstream to Upstream)

Cahaba River (Segment 01)

17.4 Fish & Wildlife Nutrients, SiltationUrban runoff / storm sewers,

municipal1998

Buck Creek to US Hwy 280

Cahaba River (Segment 02)*

36.9Outstanding AL Water, Public Water Supply,

Fish & Wildlife

Siltation and Other Habitat Alteration

Urban runoff / storm sewers

1998US Hwy 280 to

I-59

Cahaba River (Segment 03)

26.5Outstanding AL Water,

Fish & Wildlife

Nutrients, Siltation, Pathogen, and Other Habitat Alteration

Municipal, urban runoff / storm sewers, land development

1996 (Nutrients only); 1998 (all other causes

added)

Shades Creek to Buck Creek

Cahaba River (Segment 04)

24.0Outstanding AL Water

and SwimmingNutrients, Siltation, and Other Habitat Alteration

Municipal, urban runoff / storm sewers, land development

1998 (Nutrients and Other Habitat

Alteration Only); 2002 (Siltation added)

AL Hwy 82 to Shades Creek

* Segment 02 is not currently listed as being impaired for nutrients on Alabama’s §303(d) List, however due to observed impacts in recent studies it is considered part of the TMDL.

§303(d)Segments

*Currently Listed for Nutrients

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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 ID Miles Segment Location

(Downstream to Upstream)

01 17.4 Buck Creek to US Hwy 280

03 26.5 Shades Creek to Buck Creek

04 24.0 AL Hwy 82 to Shades Creek

Nutrient Impacts – What Are They?

• Aquatic life use is impaired by excessive nutrients:– Confirmed by ADEM, EPA, & Jefferson County data

– Impairment to overall community, not just T&E species

– US I-59 downstream to AL Hwy 82

• Nuisance algal blooms (excess periphyton growth)

• Dissolved oxygen violations

• Large daily swings in dissolved oxygen

• Undesirable shifts in the native species of plants and animals

Continuous Dissolved Oxygen Data

• Collected during 1999 - 2000• 2 stations in Cahaba (downstream of urban

areas and municipal facilities):– S1 = Bibb County Hwy 24– S2 = Shelby County Hwy 52

• Rainfall and Solar Radiation from Birmingham Airport

• Flows from USGS gage 02423555 at Helena (same location as S2)

Bibb County Highway 24 (S1)

• Station also known as Piper Bridge

• Downstream of Shades Creek

• Wide and flat

• No canopy

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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

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S1

Shelby County Highway 52 (S2)

• Downstream of Buck Creek

• Highly entrenched

• Canopy presentb

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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

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S1S2

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

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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

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1000

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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)

Aug 131999

Jul 141999

Cahaba River S1 versus S2 (Jul – Aug, 1999)

Nutrient Impacts – When and Where Do These Impacts Occur?

• Downstream of urban point and nonpoint sources

• 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 and 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

• Consistent with EPA Guidance and 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

Key Aspects of Nutrient Target Development (cont’d)

• ADEM and EPA Region 4 have compiled extensive resources to determine the nutrient target– Conducted field studies by EPA Region 4 and contract

scientists

– Reviewed and synthesized all information in consultation with national expert in stream nutrient-algae relationships (Jan Stevenson, PhD)

– EPA Region 4 Conclusion• Recommended range of 20 to 40 µg/L total phosphorus

should prevent filamentous algae growth and be protective of designated uses.

ADEM’s Nutrient Target Approach for the Cahaba River

• Select Set of Least-Impacted Reference Streams based on the following:– ADEM Reference Station with Sufficient Data

– Same Level III Ecoregion (Ridge & Valley)

– Mixed Land Use

– Low Levels of Measured Periphyton

– Healthy Habitat, Macroinvertebrates, and Fish Communities

• Calculate the 75th percentile of growing season data– For Ecoregion 67, Target = 35µg/L of TP

Level III Ecoregions

65

45

71

67

68

75

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Level III EcoregionsPiedmont (45)Southeastern Plains (65)Ridge and Valley (67)Southwestern Appalachians (68)Interior Plateau (71)Southeastern Coastal Plain (75)

Rivers and Streams

50 0 50 100 Miles

*Upper Cahaba River is located in Ecoregion 67

ADEM Reference Stations in Ecoregion 67

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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

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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

Ecoregion Reference Site Data

- - - - 35 µg/LTarget

Application of Nutrient Target• 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 defined as April – October

– Study Period Evaluated 1999-2001 growing seasons

Application of Target to Cahaba River: 1999-2000 TP Concentrations

Instream Evaluation Points

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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

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Instream Evaluation Points

Evaluation Points

Cahaba River Analysis• Physical characteristics

– Geometry– Tributary inflow locations

• Instream longitudinal data trends

• Point source assessment– DMR records, WWTP Nutrient Database

• Nonpoint source assessment– Correlation of GIS landuse to instream data

Modeling System• LSPC watershed model

– Utilizes precipitation to make hydrologic predictions

• EPD-RIV1 hydrodynamic and WQ model– Kinematic wave transport– Eutrophication kinetics but not periphyton

• Cahaba Spreadsheet Model– Custom mass balance framework– Predict instream TP– Evaluate point and nonpoint sources– Evaluate permit limits

• Phase I: NPDES permit revisions required by 2010*– Majors (≥1.0 MGD) – monthly avg. limit not to exceed TP = 0.40 mg/L

– Minors (<1.0 MGD) – monthly avg. limit not to exceed TP = 2.0 mg/L

• Phase II: NPDES permit revisions required by 2015*– Majors (≥1.0 MGD) – monthly avg. limit not to exceed TP = 0.20 mg/L

– Minors (<1.0 MGD) – monthly avg. limit not to exceed TP =0.50 mg/L

– Urban areas achieve 25% reduction in TP (1999-2001 baseline)

• Phase III: NPDES permit revisions required by 2020*:– Majors (≥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 = 0.30 mg/L

– Urban Areas achieve 65% reduction in TP (1999-2001 baseline)

– Cahaba River meets instream target of 35 µg/L at evaluation points

*based on assumed TMDL approval date of 2005

TMDL Implementation Strategy

Point Sources in Cahaba River Basin

Comparison of WWTP Effluent TP and Proposed TP Limits

Implementation Strategy to Reduce TP Loads

• Reducing WWTP loads:– NDPES permits for reduced effluent TP

concentrations

• Reducing MS4/urban loads:– NDPES MS4 permittees are expected to meet a

65% reduction using a BMP approach

• Reducing nonpoint source loads:– CWP and UCC– Land use planning considerations for watershed

protection

Public Participation Process• Collaborative effort between ADEM, EPA Region 4

and Cahaba Stakeholders.• Draft TMDL Report was public noticed on October

11, 2004.• 45 day public comment period which was extended

another 60 days.• Extensive public comments have been submitted to

ADEM.• Currently in the process of compiling and responding

to public comments.• TMDL will be finalized in consideration of all

comments received.

Future Activities• Follow-up monitoring plan

– Nutrient Sampling– Habitat, Macroinvertebrate, and Fish Sampling– Diurnal Dissolved Oxygen Studies– Periphyton Evaluations

• Further Ecoregion Reference Site Investigations– Ecoregion 67 and Hatchet Creek Studies

• Continued Reference Site Investigations– Develop an effects-based target– Cahaba River & Hatchet Creek Sampling

• Adaptive Management may suggest re-evaluation of TP target as new data and information becomes available.

Cahaba River

Hatchet Creek

The Cahaba LilyBlooms from early May to late June

Questions?