Redwood River TMDL Critique

David De Paz, Alana Bartolai, Lydia Karlheim

IntroductionRedwood River

• The Redwood River is impaired for both aquatic life and aquatic recreation due to fecal coliform and turbidity.

• Our critique is on the TMDL for bacteria.

• 8 reaches of the Redwood River fail to meet the water quality standard for bacteria (E. coli).

[MPCA]

Watershed CharacteristicsRedwood River

Area: 705 sq. mileTributary to the Minnesota River

The impaired reaches are classified as:

2B

2C

3B7

2B

2C

Recreation of all kind/aquatic life

Aquatic life support and recreation

stringent

Less stringent

General industrial purposes

Limited resource value

Note: Class 7 streams had not been assessed in this draftreport but will be in 2010.

Land UseRedwood River

• Land Use– 85.5% Agriculture– 2.5% urban/Residential

• Artificial drainage

BacteriaRedwood River

Causes in the watershed: • failing septic systems -there are 1,948 subsurface

sewage treatment systems. 1,051 are deemed “failing”, 334 are deemed “threats to public health”

• wastewater treatment plant bypasses and flushes (there are 8 WWTP)

• unsewered communities • livestock waste from feedlots• land applied manure (98% of total)• Domestic pets and wildlife

Standard only valid

April -October

Class 2B/2C(organisms/

100mLs)

Class 7(organisms/

100mLs)

E. coli 126 630

Fecal coliform 200 1000

[wolfenotes.com]

Sampling SitesRedwood River

[USEPA, 2011]

‘99

‘03-’06

‘99

‘99

’99-’06‘99

’99-’06

’99-’06

‘74-’06

Sites sampled by the MPCA and the Redwood-Cottonwood Rivers Control Area (RCRCA)

Fecal Coliform Redwood River

[MPCA]

Time Period: 1997-2006

(geometric mean by reach)

TMDLs were calculated for each of the 8 reaches at each flow condition (helpful for BMP implementation).

TMDL= ∑ (WLAs + ∑ LAs + MOS + RC)

TMDL DevelopmentRedwood River

point sources

nonpoint sources

accounts for uncertainty

future development

Waste load Allocations (WLAs)- • NPDES permits= 0 (Livestock facilities that have been issued NPDES permits are assigned

a zero WLA)• WWTF: assumed to be discharging the maximum of 200 orgs/100 mLs => overestimated• MS4(storm sewer systems): => MS4 + LA• The rest is assumed to be LA

Load Allocation (LA)- non-point sources not subject to NPDES permit (except land applied manure)

TMDL Allocation WLA & LARedwood River

Likely non-point sources

Land-applied manure

inadequate human WW treatment

Non-permitted municipal stormwater systems

Pets/wildlife

Reserve Capacity (RC)- • Total RC== 0 because the watershed shows trends of decreasing population and stagnant

animal numbers. Note: The MPCA will reopen the TMDLs covered in this report if adjustments are required

Margin of Safety (MOS)- • calculated per flow zone since allocations = (flow)

x conversion factors => load

• Implicit MOS: used when dry and low flow zone calculations used a concentration-based limit. In these conditions, flow is primarily GW fed and very little E. coli is conveyed.

TMDL Allocation MOS & RC Redwood River

TMDL AllocationsWest line to Threemile Creek

[MPCA]

Land use :• 82.3 %cultivated• 10.9 % urban• 4.2 % grass• 2.0 % forest• 0.5% water/wetlands• 1 WWTF with MS4 permit covering

2.86 % of the entire watershed • No feedlots with NPDES permits • 5472 animal units without permits• 140 SSTS units with 56 are failing.

TMDL AllocationsWest line to Threemile Creek

[MPCA]

TMDL Required ReductionWest line to Threemile Creek

[MPCA]

58.42%

69.65%

60.32% 60.55%

0%Inadequate

dataInadequate

data

Load Duration CurveWest line to Threemile

[MPCA]

Implementation and BMPsRedwood River

[MPCA]

BMPs:CRP buffers

alternative tile intakes

grassed waterways

livestock exclusion

sediment basins

nutrient management plans

wetland restorations

streambank stabilization

Goal:Achieve water quality standards for fecal coliform bacteria within 10 years by educating, training, and providing monetary incentives.

Note: Specific implementation plan will be made after TMDL gets approved

Critiques & Assumptions:Fecal Coliform/ E.coli

Unknowns of Fecal Coliform:

• Survival rates

• Fecal coliform may be higher when stream bed is aggravated (i.e. scouring events, runoff) [Davis et al. ,2005]

[http://www.shardcore.org]

Critiques & Assumptions:Fecal Coliform

Fecal Coliform vs. E.Coli• Standard is normalized based on comparison studies by MPCA showing that 63% of fecal

coliform will be E.Coli.

• E. coli samples converted using 179 E. coli = 200 cfu meaning that 89.5% of fecal coliform will be E. Coli.

• Substantiated using 35 sample pairs from the same Watersheds between 1985-2006

[MPCA]

Standard only valid

April -October

Class 2B/2C(organisms/

100mLs)

Class 7(organisms/

100mLs)

E. coli 126 630

Fecal coliform 200 1000

Critiques & Assumptions:Flow

• Several reaches don’t have sufficient flow monitoring data• USGS gage stations were used to find missing flow data

• Duration of monitoring data varies between stations

[USEPA, 2011]

‘99

‘03-’06

‘99

‘99

’99-’06‘99

’99-’06

’99-’06

‘74-’06

Critiques & AssumptionsImplementation

BMPs:

CRP buffers

alternative tile intakes

Grassed waterways

livestock exclusion

sediment basins

nutrient management plans

wetland restorations

streambank stabilization

Livestock manure has environmental and economic benefits:• Less prone to erosion• Reduces commercial fertilizer

Wetland restorations• affects farmers

Streambank stabilization• Can be expensive

Livestock exclusions• Requires fencing and more management

Strength Required ReductionWest line to Threemile Creek- site with largest reduction

[MPCA]

58.42%

69.65%

60.32% 60.55%

0%Inadequate

dataInadequate

data

Strengths• TMDL broken up by flow and reach

• 4 of the 8 reaches analyzed were not yet on the 303d list, but were included for thoroughness

• Entire portion of report focuses on understanding E. coli sources

• Willingness to reevaluate plan if/when changes occur ( i.e. population growth)

[MPCA]

Questions?

[confusedcow.webs.com]