Critique of North Branch of Sunrise River TMDL Nate Topie and Taylor Hoffman
Jan 21, 2016
Critique of North Branch of Sunrise
River TMDLNate Topie and Taylor Hoffman
Background
East Central MN, tributary of Sunrise River and part of larger St. Croix River Basin
Most of river basin has high or very high aquifer sensitivity to pollution
Land useType Percentage
Agriculture 58.1
Forest 8.3
Open Water 5.3
Forested Wetland 17.7
Non-Forested Wetland 8.0
Barren 0.1
Background Ctd.
Listed as impaired water under 303d of Clean Water Act due to Fecal Coliform Impaired for swimming & other primary contact
recreation
Fecal Coliform: bacteria present in intestines of warm-blooded animals Indicator for contamination by feces Indicator for presence of waterborne pathogens,
viruses, protozoa
Water Quality Standards
Standard Part 1: Monthly geometric mean should not exceed 200
organisms/100 mL Must have 5 samples per month
Standard Part 2: No more than 10% of samples taken during a month
can exceed 2000 organisms/100 mL
Standards only apply between April and October
Focused on geometric mean because less subject to random variation
Sunrise Water Quality Data
Data was collected from August-September in 1997, May-July in 1998, April-October in 2002-2003 Didn’t include 1997 data or previous data Little data for 2002-2003 seasons
Sampled at sites SUN-15 and SUN-5
Continuous flow data taken at SUN-5 and flow at other sites assumed to be proportional
Data for 2002-2003 were grouped together if from the same month
Sunrise Water Quality Data
Sunrise Water Quality Data
Sunrise Water Quality Data
Used month of June to calculate desired reduction because the month had the highest number of geometric mean exceedances 52% reduction=((geometric
mean-standard)/geometric mean) Seen as protective guideline But three out of five sample sites had less than 5
samples, what was required by standard
Not mentioned how many ‘wet’ or how many ‘dry’ samples were taken
2002 had a wet summer; 2003 had a wet spring Two seasons of data aren’t very representative of
system; no dry or very wet years present
Source Assessment
Source Assessment
TMDL and Allocations
Followed process developed by “Revised Regional TMDL Evaluation of Fecal Coliform Bacterial Impairments in Lower Mississippi River Basin in Minnesota”
WLA North Branch Wastewater Treatment Plant MS4
Determined from TMDL-WLAWWTP-MOS, which was divided between non-point and MS4 based on land percentages
Leaking septic systems; illegal straight pipes assumed to be zero
LA Non-point: livestock, septic systems, wildlife, pets outside of
MS4 Remaining 68% after WLAWWTP, MOS, and WLAMS4 were subtracted
from TMDL
Margin of Safety and Reserve Capacity
MOS given by difference between the central and lowest value for each zone Used this method because the allocations are direct
functions of daily flows MOS will account for flow variability
Reserve Capacity assumed equal to zero As growth increases, assumed that fecal coliform
will decrease Sewer systems with disinfection will take the place of
livestock populations
TMDL and Sources
Public Participation
Included organizations/persons such as: Minnesota DNR, MPCA, Chisago SWCD, North
Branch City Council, Wild River State Park, U of M Extension, volunteer stream monitors, landowners, and interested citizens.
Included a steering committee, public information meetings, and publications in local press
Monitoring Plan
Test specifically for E. coli instead of broadly fecal coliform
Monitor at same sites
Samples taken 5 times per month April through October
At least two seasons
Implementation
Focus on reducing top 3 sources (top 80%): unregulated livestock facilities, pasture near streams, and dangerous septic systems
Numerous financial incentives for landowners
Time frame: 5-10 years
Goals of Implementation
Reduce fecal coliform load from unregulated livestock facilities. Store waste, vegetative buffer strips, move fences,
clean lot
Reduce load from pastures near streams Move livestock, rotational grazing
Reduce load from septic systems Bring into compliance, switch to city sewer
Surface applied manure, pets, wildlife
Summary
Calculation of the components of the TMDL were valid (WLA, LA, MOS, Reserve Capacity)
52% reduction seems reasonable
Top three goals in implementation make sense Valid to focus on those sources for implementation
since they were derived from more reliable calculations
Would be easier to pinpoint and decrease (vs. wildlife fecal contamination)
The sources of those goals produced high amounts of fecal coliform during wet and dry periods
Summary
Could use more data Not enough grab samples in between two seasons
Below requirement of 5 samples per month Would make the geometric mean and therefore reduction goal
more accurate if more samples were taken Only two years used for data collection
Though they compared to 1998, could be helpful to include more years of data
Also, mentioned in beginning of report that there was close to 20 years of data; where is it/can it be used?
TMDL calculation was roughly approximated for some sources; however this couldn’t really have been improved