redwood river tmdl critique
DESCRIPTION
Redwood River TMDL Critique. David De Paz, Alana Bartolai , Lydia Karlheim. Introduction Redwood 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. - PowerPoint PPT PresentationTRANSCRIPT
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]