Redwood River Turbidity

Total Maximum Daily Load

Report

Draft – March, 2011

For Submission to:

U.S. Environmental Protection Agency Region 5 Chicago, Illinois

Submitted by:

Project Technical Team Local project support: Douglas Goodrich, Shawn Wohnoutka – Redwood Cottonwood Rivers Control Area Advisory Committee members

Minnesota Pollution Control Agency project support and management: Mark T. Hanson, Regional Division—Marshall Kelli Daberkow, Regional Division—Marshall

Table of Contents

Executive Summary ...... 1 1.0 Introduction ...... 4 1.1 Purpose ...... 4 1.2 Project Background ...... 6 2.0 Watershed Characteristics ...... 7 2.1 Demographics ...... 7 2.2 Location and Topography ...... 9 2.3 Land Use ...... 13 2.4 Temperature ...... 16 2.5 Precipitation ...... 16 2.6 Stream Flow Dynamics ...... 17 3.0 Description of Applicable Water Quality Standards and Assessment Procedures ...... 19 3.1 Classification and Beneficial Uses ...... 19 3.2 Applicable Minnesota Water Quality Standards ...... 20 3.3 Impaired Assessment ...... 20 3.4 Fecal Coliform and E. coli Standards ...... 27 3.5 Monthly Fecal Coliform Concentrations in the Redwood River ...... 27 3.6 MPCA Non-degradation Policy ...... 28 3.7 Trends in Fecal Coliform Surface Water Quality ...... 28 4.0 Description of Fecal Coliform Bacteria and Its Sources ...... 30 4.1 Fecal Coliform Bacteria Description ...... 30 4.2 Fecal Coliform Bacteria Sources ...... 30 4.2A Human Sources ...... 30 4.2B Livestock Sources ...... 32 4.2C Pet Sources ...... 37 4.2D Wildlife (Natural Background) Sources ...... 37 5.0 TMDL Development for the Redwood River Watershed ...... 39 5.1 Approach to Allocations Needed to Satisfy the TMDLs ...... 39 5.2 Components of TMDL Allocations ...... 41 5.2A Wasteload Allocation ...... 42 5.2B Load Allocations ...... 43 5.2C Margin of Safety ...... 43 5.2D Reserve Capacity ...... 44 5.3 TMDL Allocations for Individual Impaired Reaches ...... 47 5.3.1 Redwood River; Ramsey Creek to Minnesota River ...... 47 5.3.2 Redwood River; Clear Creek to Redwood Lake ...... 52 5.3.3 Clear Creek; Headwaters to Redwood River ...... 56 5.3.4 Redwood River; T111 R42W S33 Westline to Threemile Creek – Below Marshall ...... 60 5.3.5 Redwood River; T111 R42W S33 Westline to Threemile Creek – Above Marshall ...... 64 5.3.6 Threemile Creek; Headwaters to Redwood River ...... 68 5.3.7 Redwood River; Headwaters to Coon Creek ...... 72

5.3.8 Tyler Creek; Headwaters to Redwood River ...... 77 5.3.9 Coon Creek; Lake Benton to Redwood River ...... 81 6.0 Margin of Safety (MOS) ...... 85 7.0 Seasonal Variation ...... 85 8.0 Monitoring ...... 87 9.0 Implementations ...... 87 9.1 Implementation through Source Reduction Strategies ...... 87 9.2 Locally Targeted Implementation ...... 90 10.0 Reasonable Assurance ...... 92 10.1 Evidence of BMP Implementability ...... 92 10.2 Non-regulatory, Regulatory, and Incentive-Based Approaches ...... 93 11.0 Public Participation ...... 94 12.0 References ...... 95

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Figures

2.01 Map of Population Centers in the Redwood River Watershed ...... 8 2.02 Location Map of Redwood River Watershed ...... 10 2.03 Elevation Map of Redwood River Watershed...... 11 2.04 Average Monthly Temperatures ...... 16 2.05 Precipitation Data; Redwood River Watershed (1971-2000) ...... 17 2.06 Mean Monthly Flow; Redwood River at Redwood Falls (1940-2000) ...... 17 2.07 Mean Monthly Flow; Redwood River at Marshall (1940-2000) ...... 18 3.01 Water Monitoring sites in Redwood River Watershed ...... 23 3.02 E. coli – Fecal Coliform Ratio ...... 27 3.03 Redwood River Watershed Fecal Coliform Geometric Mean by Sampling Site (1997-2006) ...... 28 3.04 Redwood River, at North Redwood, Fecal Coliform Geometric Mean by Decade ...... 29 3.05 Redwood River, at North Redwood, Fecal Coliform Geometric Mean by Half-Decade ...... 29 4.01 2003 Registered Feedlots in the Redwood Watershed ...... 36 5.01 Redwood River Flow Duration Curve Daily Mean (1940-2006) ...... 40 5.3.x Figures for Individual Reaches ...... 47 5.3.xA Map of Sub-watersheds 5.3.xB Monthly Geometric Mean Fecal Coliform Concentrations 1997-2006 7.01 Seasonal Variation of Fecal Coliform (cfu/100mL) & Flow (MGD) At Site RR1 ...... 86

Tables 1.01 Redwood River Watershed Impaired Reaches Descriptions and Assessment Summaries ...... 5 2.01 Local Units of Government in the Redwood River Watershed ...... 7 2.02 Redwood River Watershed Land Use by County in Acres and Percentages ...... 14 2.03 Redwood River Land Use by Impaired Reach ...... 15 2.04 Cumulative Land Use in the Redwood River Watershed by Impaired Reach ...... 15 3.01 RWR-1 site: 1974-2006 Fecal Coliform Bacteria Sampling by Month ...... 24 3.02 Fecal Coliform Bacteria Sampling Data in the Redwood River Watershed, all sites: 1999-2006 ...... 25 3.03 Redwood River Watershed Assessment Site Descriptors ...... 26 4.01 Wastewater Treatment Facilities in the Redwood Watershed ...... 31 4.02 Redwood River “Unsewered” Communities ...... 31 4.03 Redwood River Watershed Feedlot Inventory ...... 34 4.04 Inventory of Fecal Coliform Producers in the Watershed ...... 38 5.01 Flow Categories for the Redwood River at USGS Station #05316500 ...... 40 5.02 Conversion Equations ...... 41 5.03 Total Maximum Daily Load and Margin of Safety for the Redwood River at USGS Station #05316500 ...... 45 5.04 Redwood River Watershed Impaired Reaches Description And Watershed Areas ...... 46 5.3 TMDL Allocations for Individual Reaches ...... 47 Section 5.3 contains the following tables for all impairment: A. Wastewater Treatment Facilities B. Municipal Separate Storm Sewer System (MS4) Communities C. Livestock Facilities with NPDES Permits D. Daily Fecal Coliform Loading Capacities and Allocations 7.01 Flow Duration Curve Loading by Months ...... 86 9.01 Implementation Opportunities for the Different flows Regimes ...... 88

Appendix A: Redwood River Fecal Coliform TMDL: Methodology for TMDL Equations and Load Duration Curves...... 97 Appendix B: Load Duration Curves for the Impaired Reaches ...... 100 Appendix C: Fecal Coliform Loading by Source: Methodology and Estimates of Relative Contributions ...... 105 Appendix D: Agendas, Presentations and Handouts ...... 109 Appendix E: Responses to Written Comments ...... 117

TMDL Summary Table Waterbody ID Redwood River: Ramsey Creek to MN River TMDL Fecal Coliform 07020006-501 Page # Redwood River: Clear Creek to Redwood Lake Fecal Coliform 07020006-509 5 Clear Creek: Headwaters to Redwood River Fecal Coliform 07020006-506 Redwood River: T111 R42W S33 west line to Threemile Creek (including and below city of Marshall) Fecal Coliform 07020006-502A Redwood River: T111 R42W S33 west line to Threemile Creek (excluding and above city of Marshall) Fecal Coliform 07020006-502B Threemile Creek: Headwaters to Redwood River Fecal Coliform 07020006-509

Location The Redwood River Watershed is located in 9, 10 Southwestern Minnesota and is a tributary to the Minnesota River Basin. The Redwood River originates in Pipestone County and flows to the East-Northeast through parts of Murray, Lincoln, Lyon and Yellow Medicine before entering the Minnesota River in Redwood County. 303(d) Listing The MPCA’s projected schedule for TMDL 4, 5, 6 Information completions, as indicated on Minnesota’s 303(d) impaired waters list, implicitly reflects Minnesota’s priority ranking of this TMDL. Portions of the project were scheduled to begin at 2004, 2007, and 2009 and be completed in 2012. All listings are for Fecal Coliform impairment and include; Redwood River from Ramsey Creek to the Minnesota River (listed 1994), Redwood River from T111 R42W S33 west line to Threemile Creek (2004), Threemile Creek from headwaters to Redwood River (2006), Redwood River from Clear Creek to Redwood Lake (2006), Redwood River from headwaters to Coon Creek (2008), Clear Creek from headwaters to Redwood River (2008), Coon Creek from Lake Benton to Redwood River (2008) and Tyler Creek from headwaters to Redwood River (not listed, but data indicates impairment) Impairment / TMDL 5, 6 Pollutant(s) of Impaired for Aquatic Recreation by Fecal Coliform Concern Impaired Beneficial The applicable water body classifications and water 5 Use(s) quality standards are specified in Minnesota Rules

Chapter 7050. Minnesota Rules Chapter 7050.0407 lists water body classifications and Chapter 7050.2222 subp. 5 lists applicable water quality standards for the impaired reaches for Aquatic Recreation. Applicable Water Minnesota Rules Chapter 7050 provides the water 5, 6, Quality Standards/ quality standards for Minnesota waters. The rules are as 19, 20, Numeric Targets follows for Class 2B surface waters for fecal coliform 21 bacteria: The quality of Class 2B surface waters shall be such as to permit the propagation and maintenance of a healthy community of cool or warm water sport or commercial fish and associated aquatic life, and their habitats. These waters shall be suitable for aquatic recreation of all kinds, including bathing, for which the waters may be usable. Fecal coliform organism not to exceed 200 organisms per 100 milliliters as a geometric mean of not less than five samples in any calendar month, nor shall more than ten percent of all samples taken during any calendar month individually exceed 2000 organisms per 100 milliliters. The standard applies only between April 1 and October 31. Loading Capacity Flow regimes were determined for high, moist, mid- 33, 34, (expressed as daily range, dry and low flow conditions. The mid-range flow 35 load) value for each flow regime was then used to calculate the total monthly loading capacity (TMLC). Thus, for the “high flow” regime, the loading capacity is based on the monthly flow value at the 5th percentile. The flow used to determine daily loading capacity for each flow regime was multiplied by a conversion factor of 4,892,279,040. Fecal coliform TMDLs are expressed in both monthly and maximum daily terms. This is to ensure that both the monthly geometric mean and upper tenth percentile portions of the water quality standard are addressed. All maximum daily loading capacity and allocation values are set at a third the monthly loading capacity. In conceptual terms, three days of bacteria loads that approach the maximum daily capacities will “use up” most of the monthly capacity. A greater percentage of days would be considered dry; however the majority of bacterial loading to streams occurs during wet conditions.

Wasteload 49, 50 Allocation

Fecal Coliform Source Permit # Individual

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Redwood River: WLA Ramsey Creek to CAFOs Minnesota River Alpha Acres 127-50018 0 (07020006-501) Total = 0 Source Permit # Individual WLA MS4 Redwood Falls MS400236 Flow Dependant Total = See Page 50 Source Permit # Individual WLA WWTF N/A N/A N/A Total = 0 Source Permit # Individual WLA Straight-Pipe-Septics Illegal Discharges N/A 0 Total = 0 Source Permit # Individual WLA Reserve Capacity N/A N/A N/A Total = 0 Wasteload Source Permit # Individual 53, 54 Allocation WLA CAFOs Fecal Coliform Charles & Glen Redwood River: Rohlik Farm 127-55073 0 Clear Creek to Andrew Schiller Redwood Lake Farm – Vesta Site 127-50087 0 (07020006-509) Bruce Meier Farm 127-50004 0 Total = 0 Source Permit # Individual WLA MS4 N/A N/A N/A Total = 0 Source Permit # Individual WLA WWTF Vesta MNG580043 .27 Total = .27

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Source Permit # Individual WLA Straight-Pipe-Septics Illegal Discharges N/A 0 Total = 0 Source Permit # Individual WLA Reserve Capacity N/A N/A N/A Total = 0 Wasteload Source Permit # Individual 57, 58 Allocation WLA CAFOs Fecal Coliform Jim Tauer Farm 083-65820 0 Clear Creek: Total = 0 Headwaters to Source Permit # Individual Redwood River WLA (07020006-506) MS4 N/A N/A N/A Total = 0 Source Permit # Individual WLA WWTF Milroy MN0041211 .26 Total = .26 Source Permit # Individual WLA Straight-Pipe-Septics Illegal Discharges N/A 0 Total = 0 Source Permit # Individual WLA Reserve Capacity N/A N/A N/A Total = 0 Wasteload Source Permit # Individual 61, 62 Allocation WLA CAFOs Fecal Coliform N/A N/A N/A Redwood River: Total = 0 T111 R42W S33 Source Permit # Individual west line to WLA Threemile Creek MS4 (including and Marshall #MS400241 Flow Dependant

below city of Total = See Page 45,62 Marshall) Source Permit # Individual (07020006-502A) WLA WWTF Marshall MN0022179 34.07 Total = 34.07 Source Permit # Individual WLA Straight-Pipe-Septics Illegal Discharges N/A 0 Total = 0 Source Permit # Individual WLA Reserve Capacity N/A N/A N/A Total = 0 Wasteload Source Permit # Individual 65, 66 Allocation WLA CAFOs Fecal Coliform N/A N/A N/A Redwood River: Total = 0 T111 R42W S33 Source Permit # Individual west line to WLA Threemile Creek MS4 (excluding and N/A N/A N/A above the city of Total = 0 Marshall) (07020006-502B) Source Permit # Individual WLA WWTF Russell MNG580062 .64 Lynd MNG580030 .35 Total = .99 Source Permit # Individual WLA Straight-Pipe-Septics Illegal Discharges N/A 0 Total = 0 Source Permit # Individual WLA Reserve Capacity N/A N/A N/A Total = 0 Wasteload Source Permit # Individual 69, 70 Allocation WLA

CAFOs Fecal Coliform Grandview Farms 083-60023 0 Threemile Creek: Inc. Headwaters to Dieken Inc. 083-50016 0 Redwood River Robert Buysee Farm 083-89076 0 (07020006-504) Total = 0 Source Permit # Individual WLA MS4 N/A N/A N/A Total = 0 Source Permit # Individual WLA WWTF Ghent MN0039730 .28 Total = .28 Source Permit # Individual WLA Straight-Pipe-Septics Illegal Discharges N/A 0 Total = 0 Source Permit # Individual WLA Reserve Capacity N/A N/A N/A Total = 0 Wasteload Source Permit # Individual 73, 74 Allocation WLA CAFOs Fecal Coliform Norgaard Family Redwood River: Farms 081-87296 0 Headwaters to Coon Total = 0 Creek Source Permit # Individual (07020006-505) WLA MS4 N/A N/A N/A Total = 0 Source Permit # Individual WLA WWTF Ruthton MN0049654 .39 Total = .39 Source Permit # Individual WLA

Straight-Pipe-Septics Illegal Discharges N/A 0 Total = 0 Source Permit # Individual WLA Reserve Capacity N/A N/A N/A Total = 0 Wasteload Source Permit # Individual 78, 79 Allocation WLA CAFOs Fecal Coliform Donald L. Buhl Farm 081-50002 0 Tyler Creek: Total = 0 Headwaters to Source Permit # Individual Redwood River WLA (07020006-512) MS4 N/A N/A N/A Total = 0 Source Permit # Individual WLA WWTF Tyler MN0022039 1.32 Total = 1.32 Source Permit # Individual WLA Straight-Pipe-Septics Illegal Discharges N/A 0 Total = 0 Source Permit # Individual WLA Reserve Capacity N/A N/A N/A Total = 0 Wasteload Source Permit # Individual 82, 83 Allocation WLA CAFOs Fecal Coliform David & Karen Coon Creek: Keifer Farm 083-50005 0 Lake Benton to Total = 0 Redwood River Source Permit # Individual (07020006-511) WLA MS4 N/A N/A N/A Total = 0

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Source Permit # Individual WLA WWTF N/A N/A N/A Total = 0 Source Permit # Individual WLA Straight-Pipe-Septics Illegal Discharges N/A 0 Total = 0 Source Permit # Individual WLA Reserve Capacity N/A N/A N/A Total = 0

Load Allocation Flow Regime Individual LA Page # Fecal Coliform High 2784.3 50 Redwood River: Moist 628.2 Ramsey Creek to Mid 237.2 Minnesota River Dry (07020006-501) Low Load Allocation Flow Regime Individual LA 54 Fecal Coliform High 2618.6 Redwood River: Moist 431.3 Clear Creek to Mid 165.7 Redwood Lake Dry (07020006-509) Low Load Allocation Flow Regime Individual LA 58 Fecal Coliform High 356.0 Clear Creek: Moist 62.6 Headwaters to Mid 26.9 Redwood River Dry 4.1 (07020006-506) Low Load Allocation Flow Regime Individual LA 62 Fecal Coliform High 457.4 Redwood River: Moist 38.5 T111 R42W S33 Mid west line to Dry Threemile Creek (including and below city of Low

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Marshall) (07020006-502A) Load Allocation Flow Regime Individual LA 66 Fecal Coliform High 451.5 Redwood River: Moist 65.6 T111 R42W S33 Mid 23.4 west line to Dry 2.1 Threemile Creek (excluding and above city of Marshall) Low (07020006-502B) Load Allocation Flow Regime Individual LA 70 Fecal Coliform High 520.4 Threemile Creek: Moist 91.5 Headwaters to Mid 39.5 Redwood River Dry 6.1 (07020006-504) Low Load Allocation Flow Regime Individual LA 74 Fecal Coliform High 400.9 Redwood River: Moist 58.9 Headwaters to Coon Mid 21.4 Creek Dry 2.6 (07020006-505) Low Load Allocation Flow Regime Individual LA 79 Fecal Coliform High 448.0 Tyler Creek: Moist 66.3 Headwaters to Mid 24.5 Redwood River Dry 3.4 (07020006-512) Low Load Allocation Flow Regime Individual LA 83 Fecal Coliform High 168.7 Coon Creek: Moist 25.4 Lake Benton to Mid 9.7 Redwood River Dry 1.8 (07020006-511) Low 0 Margin of Safety Because the allocations are a direct function of monthly 43, 44, flow, accounting for potential flow variability is the 85 appropriate way to address the MOS explicitly for the fecal coliform and turbidity impairments. This is done within each of five flow zones. The MOS was determined as the difference between the median flow and minimum flow in each zone.

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Seasonal Variation Monitoring data show an apparent relationship between 85, 86 season and fecal coliform bacteria concentrations. Typically the highest bacterial concentrations are found in the summer and early fall. In the spring, concentrations are typically lower, despite the fact that significant manure application occurs during this time and that field shave little crop canopy to protect against water erosion. Reasonable The source reduction strategies detailed in the 92, 93 Assurance implementation plan section have been shown to be effective in reducing pathogen transport/survival. Many of the goals outlined in this TMDL study run parallel to objectives outlined in the local Water Plans. Various program and funding sources will be used to implement measures that will be detailed in an implementation plan to be completed. Through existing permit programs, fecal coliform impairments are being addressed and monitored. In the future, it can be assumed that this will continue. Monitoring A detailed monitoring plan will be included in the 87 Implementation Plan to be completed. Currently, there are monitoring efforts in the watershed. Implementation A summary of potential management measures was 87, 88, included. More detail will be provided in the 89, 90, implementation plan. 91, 92 Public Participation A group of local state and federal official have been 94 meeting periodically to receive TMDL updates and will be contributing to the development of the implementation plan. There have been news releases and website updates regarding this project. Public Comment period: [dates] Meeting location: Redwood Falls Comments received? Yes

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Turbidity Total Maximum Daily Load Assessment Report Redwood River Watershed, Minnesota

Executive Summary The Clean Water Act, Section 303(d), requires that every two years, States publish a list of streams and lakes that do not meet water quality standards. Waters placed on the list are considered “impaired”, leading to the requirement of a Total Maximum Daily Load (TMDL). TMDL assessments determine the maximum amount of pollutant a stream can receive, while maintaining water quality standards. A TMDL is divided into a wasteload allocation (point sources), load allocation (non-point sources and natural background) and a margin of safety. There are currently two impaired uses on the Redwood River (HUC – 07020006): Aquatic Recreation and Aquatic Life, due to turbidity, fecal coliform bacteria and impaired biota. There are other impairments due to fecal coliform and impaired biota, but they are not addressed directly by this plan. This Total Maximum Daily Load (TMDL) report (Report) describes the magnitude of the problem and provides direction for improving water quality at the listed reaches. Four reaches are assessed in this report. This Report evaluates the turbidity values and total suspended solids (TSS) concentrations and load reductions needed for the four reaches in the Redwood River to meet Minnesota water quality standards.

The Redwood River originates near Ruthton in northeast Pipestone County, Minnesota and flows about 125 miles northeast through Redwood Lake and to the Minnesota River at North Redwood. The dominant land use in the Redwood River Watershed is cultivated agricultural crops. The largest cities within the watershed include Lake Benton, Marshall, and Redwood Falls. The Redwood River watershed is approximately 451,250 acres or 705.1 square miles. The Redwood Cottonwood Rivers Control Area (RCRCA) monitors the watershed at four sampling stations on a regular basis. The focus of this report is to better identify TSS levels, probable sources, and estimate load reduction needs to meet water quality goals for the Redwood River.

The majority of water quality monitoring data used in this Report was collected from 1990 to 2009 by MPCA and RCRCA staff. Findings based on these tests results showed that several reaches of the Redwood River watershed were impaired due to excess turbidity, as well as other pollutants. The Minnesota Pollution Control Agency (MPCA) has listed four stream reaches in the Redwood River Watershed as impaired waters for exceeding the turbidity standard for aquatic life, which is currently set at 25 Nephelometric Turbidity Units (NTU).

Turbidity is a measurement of the clarity of water, determined by how much light is absorbed and scattered in a water sample (MPCA, 2005). It is not a direct measure of pollutant mass. However, because light scatter and absorption is strongly affected by particles suspended in the water, there is a strong relationship between turbidity and the commonly used mass-based water quality parameter total suspended solids (TSS). For

1 Redwood River Fecal Coliform TMDL Report this reason, and because mass loads are needed for TMDL calculations and allocations, TSS is commonly used as a surrogate for turbidity.

A large data set of paired TSS and turbidity values from samples taken in the Minnesota, Lower Mississippi, Cedar, Des Moines and Missouri River basins indicate that it is possible to use TSS values to predict turbidity. Correlation analysis shows a strong relationship between turbidity and TSS measurements (MPCA, 2001).

Turbidity is a dimensionless unit and cannot be converted into loads. To use the 25 NTU turbidity standard in a load allocation scenario, a relationship between turbidity and the total suspended sediment concentration (TSS) was developed. The Minnesota River Turbidity TMDL developed TSS surrogate values for ten tributaries to or stretches of, the Minnesota River. Using paired turbidity and TSS measurements in the Redwood and Cottonwood Rivers study area, along with regression analysis, a 70 mg/L TSS was used for the equivalent 25 NTU estimated measurement (MPCA, 2008).

Sediment sources vary from uplands to near-channel sources such as ravines, bluffs, streambanks, and impervious areas. Research is helping to define the extent and magnitude of these sources. Implementation strategies will need to focus on all these sources to be successful. While there is considerable uncertainty about the actual magnitude of these sources, these are the areas where increased focus would seem to have the most potential for water quality improvements.

This Report used a flow duration curve approach to determine the TSS loading capacity at the impaired reaches under varying flow regimes. The Report focuses on TSS loading capacity and general allocations necessary to meet water quality standards at individual impaired river or stream reaches, rather than on precise loading reductions that may be required from specific sources.

Turbidity loading capacities were calculated for each individual impaired reach, and those capacities are allocated among point sources (wasteload allocation), nonpoint sources (load allocation), and a margin of safety. A loading capacity is the product of stream flow at each impaired reach and the TSS water quality standard. Five flow zones, ranging from low flow to high flow are utilized, so that the entire range of conditions is accounted for in the Report. The loading capacity and allocation vary by impaired reach, and by flow zone for a given reach. A description of the duration curve approach is in Appendix A.

The Report describes the above sources and dynamics in more detail. The Report also describes applicable water quality standards for turbidity, land use, population, climatic conditions and potential sources, TMDL allocations, a monitoring plan and suggested implementation strategies.

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1.0 Introduction

1.1 Purpose

Section 303(d) of the Clean Water Act (CWA) provides authority for completing Total Maximum Daily Loads (TMDLs) to achieve state water quality standards and/or their designated uses. The TMDL process establishes the allowable loadings of pollutants for a water body based on the relationship between pollution sources and in-stream water quality conditions. TMDLs provide states a basis for determining the pollutant reductions necessary from both point and nonpoint sources to restore and maintain the quality of their water resources.

A TMDL or Total Maximum Daily Load (TMDL) is a calculation of the maximum amount of a pollutant that a water body can receive and still meet water quality standards, and an allocation of that amount to the pollutant's sources. Section 303(d) of the Clean Water Act (CWA) and its implementing regulations (40 C.F.R. § 130.7) require states to identify waters that do not or will not meet applicable water quality standards and to establish TMDLs for pollutants that are causing non-attainment of water quality standards.

Water quality standards are set by States, Territories, and Tribes. They identify the uses for each water body; for example, drinking water supply, contact recreation (swimming), aquatic life support (fishing), and the scientific criteria to support that use.

A TMDL needs to account for seasonal variation and must include a margin of safety (MOS). The MOS is a safety factor that accounts for any lack of knowledge concerning the relationship between effluent limitations and water quality. Also, a TMDL must specify pollutant load allocations among sources. The total of all allocations, including wasteload allocations (WLA) for point sources, load allocations (LA) for nonpoint sources (including natural background), and the MOS (if explicitly defined) cannot exceed the maximum allowable pollutant load:

TMDL =sumWLAs + sumLAs + MOS + RC*

* The MPCA also requires that “Reserve Capacity” (RC) which is an allocation for future growth be addressed in the TMDL.

Where:

WLA = wasteload allocation; the portion of the TMDL allocated to existing or future point sources of the relevant pollutant;

LA = load allocation; or the portion of the TMDL allocated to existing or future nonpoint sources of the relevant pollutant. The load allocation may also encompass natural background contributions;

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MOS = margin of safety, or an accounting for uncertainty about the relationship between pollutant loads and receiving water quality. The margin of safety can be provided implicitly through analytical assumptions or explicitly by reserving a portion of the loading capacity; and

RC = reserve capacity, an allocation for future growth.

A TMDL study identifies all sources of the pollutant and determines how much each source must reduce its contribution in order to meet the quality standard. The sum of all contributions must be less than the maximum daily load.

Sources that are part of the waste load allocation are largely controlled through National Pollutant Discharge Elimination System (NPDES) permits. Load allocation sources are controlled through a variety of regulatory and non-regulatory efforts at the local, state, and federal level.

The state agency responsible for assessing, listing, and reporting impaired waters is the Minnesota Pollution Control Agency (MPCA). In 2002 the MPCA identified two reaches impaired for turbidity in the Redwood River watershed and added another reach in 2004. In 2010, the MPCA listed one additional reach impaired for turbidity. Table 1.01 summarizes the listings, sites and data collected at each of the impaired reaches, as of the MPCA 2007 impairment listing.

The MPCA’s projected schedule for TMDL completions, as indicated on Minnesota’s 303(d) impaired waters list, implicitly reflects Minnesota’s priority ranking of this TMDL. Portions of the project were scheduled to begin at 2006 and be completed in 2012. A willing local group allowed for an earlier completion of the TMDL. Ranking criteria for scheduling TMDL projects include, but are not limited to: impairment impacts on public health and aquatic life; public value of the impaired water resource; likelihood of completing the TMDL in an expedient manner, including a strong base of existing data and restorability of the waterbody; technical capability and willingness, locally, to assist with the TMDL; and appropriate sequencing of TMDLs within a watershed or basin.

Table 1.01: Redwood River Watershed Impaired Reaches Descriptions and Assessment Summaries

Year River Assessment Unit Monitoring Stations % of data Years of Reach Description listed ID Used for Assessment in violation Data

Redwood T111 R42W S33 west River line to Threemile Cr 02 07020006-502 MPCA Determination 0% ’98

Redwood Three Mile Creek to River Clear Creek 10 07020006-503 S004-299 71.4% ‘06

Three Mile Headwaters to Creek Redwood River 04 07020006-504 S002-313 20.6% ‘97-‘05

Redwood Clear Creek to River Redwood Lake 02 07020006-509 S001-679 48.0% ‘97-‘05

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The protocol for this assessment is outlined in MPCA “Listing Methodology” publications found at: http://www.pca.state.mn.us/water/tmdl/index.html#support. The applicable water body classifications and water quality standards are specified in Minnesota Rules Chapter 7050. Minn. R. ch. 7050.0222, subp. 5 lists applicable water quality standards for the impaired reaches and Minn. R. ch. 7050.0407 lists water body classifications. Assessment summary information for the four reaches is listed in Table 1.01. The MPCA uses data collected over the most recent ten year period for all water quality assessments considered for 303(d) impairments. Years of record are based on the USGS water year. Water years are from October 1 of one year through September 30 of the following year. Data for all 10 years of the period are not required to make an assessment. The 10 year period is used to provide reasonable assurance that data will have been collected over a range of weather and flow condition and that all seasons will be adequately represented. The USGS water year is only used in this report for impairment determinations, all other data is presented by calendar year. The assessment protocol dictates a hierarchy of which pollutant to use in order to make an assessment of the waterbody’s condition. This hierarchy is better spelled out in section 3.0 - 3.2 Applicable Water Quality Standards and Assessment Procedures.

1.2 Project Background

The Redwood River Clean Water Project (RRCWP) was awarded a Clean Water Partnership (CWP) Phase I Diagnostic Study grant by the MPCA in 1989 to begin an intensive study of land use and water quality in the Redwood River Watershed. The RRCWP was awarded a Phase II Implementation grant from the MPCA in 1994 to carry out the remediation strategies determined in the Phase I CWP. Subsequent grants were carried out to continue the implementation of Best Management Practices (BMPs) outlined in the RRCWP Implementation Plan as well as continued monitoring of surface waters in the watershed. Most of the data used in this report is a result of monitoring efforts through the RRCWP. The diagnostic study focused on monitoring the watershed to determine water quality and determine non-point sediment sources to the Redwood River corridor to get a better grasp on the sedimentation of Redwood Lake. MPCA guidance directs TMDL authors that if sufficient turbidity measurements exist, only turbidity measurements will be used to determine impairment. RCRCA samples taken during and since the 2003 sample season were tested for turbidity. RCRCA samples taken before 2003 were tested for TSS but not turbidity. Since there is sufficient turbidity data at RCRCA sampling sites, the pre-2003 TSS data will not be used in determining future impairments, but may be used in this report to show trends or previous conditions. Since 2003, sampling was done on four sites; two on the Redwood mainstem and one each near the mouth of tributaries Clear Creek and Threemile Creek. Beginning in 2009, two additional sites were added on the Redwood mainstem along the impaired reach from T111 R42W S33, west line to Threemile Creek (AUID:07020006-502).

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2.0 Watershed Characteristics

2.1 Demographics

The Redwood River is a tributary to the Minnesota River located in southwestern Minnesota in the counties of Lincoln, Lyon, Murray, Pipestone, Redwood, and Yellow Medicine. There are eleven incorporated communities located within the watershed include Marshall, Redwood Falls, Tyler, Russell, and Vesta and there are three unincorporated communities. Table 2.01 shows the townships and cities located in the watershed in each county.

Table 2.01: Local Units of Government in the Redwood River Watershed County Township Cities Pipestone 2 1 Murray 1 0 Lincoln 8 2 Lyon 15 7 Yellow Medicine 2 0 Redwood 11 4 Total 39 14

Southwestern Minnesota is predominantly rural with a relatively dispersed population. A little over one percent of the watershed is urban. Urban population for communities and cities within the Redwood River watershed is approximately 15,879. Rural population within the Redwood River watershed is approximately 5,202, based on the number of septic systems reported to the State of Minnesota by each county multiplied by 2.67 persons per household, a statistic calculated by the 2000 Census. The total population is 21,081 people. About 60 percent of the total population lives in the City of Marshall (12,735), the largest city within the watershed. Portions of the city of Redwood Falls (5,459) is also in the watershed and affect the Redwood River through storm water runoff related to urban land uses and impervious surfaces. Figure 2.01 shows city locations in the watershed.

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Figure 2.01: Population Centers in the Redwood River Watershed

7 Redwood River Fecal Coliform TMDL Report

2.2 Location and Topography

The watershed area is located roughly north of Latitude 44 07’ 00” and east of Longitude -96 24’ 00” covering an area of 705 square miles. The Redwood River Watershed is located in Southwestern Minnesota and is a tributary to the Minnesota River Basin. The Redwood River originates in Pipestone County and flows to the East- Northeast through parts of Murray, Lincoln, Lyon and Yellow Medicine before entering the Minnesota River in Redwood County. Figure 2.02 shows the watershed location within the state.

The topography of the Redwood River watershed is that of a rolling upland area. Altitudes descend from west to east with the Coteau des Prairies serving as a watershed divide. Natural drainage patterns in the area were established by valleys formed from glacial meltwaters during the Pleistocene Epoch. End moraines, which were formed during the recession of the last glacier, are the most prominent features. They formed a series of morainic belts, generally running from north to south or northwest to southeast. An elevation map with TMDL reaches in Figure 2.03 shows the high variation of terrain in the watershed.

The Redwood River drops from an elevation of about 1,850 feet above sea level in northeastern Pipestone County to 1140 feet at Marshall, an average of about eighteen feet per mile. The river slope then flattens to an average of about four feet per mile between Marshall and Redwood Falls. Between Redwood Falls and its confluence with the Minnesota River near North Redwood, the river’s slope increases sharply to an average of 24 feet per mile.

The upland plain is characterized by parallel glacial moraines and glacial till superimposed on bedrock. The Redwood River watershed lies entirely within the Prairie Pothole Region, which is noted for poor natural drainage, and there were many small marshes, ponds, and shallow lakes. Installation of widespread artificial drainage systems, however, has reduced today’s numbers to only a fraction of what once existed. Significant channel alterations were made to the river between the city of Marshall and Lake Redwood. Alterations between State Highway 23 (river mile 58.3) and Seaforth (river mile 20.3) included excavation and straightening in three reaches and eight cutoffs and continuous clearing. Later, seven additional cutoffs were authorized and completed. This section of the river was designated Judicial Ditch 37.

The lowland plain’s geologic composition is glacial till derived from ground moraines overlying bedrock. The land is gently rolling to flat. Row crop agriculture is the predominant land use which has been aided by use of extensive artificial drainage systems.

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Figure 2.02: Location of Redwood River Watershed

9 Redwood River Fecal Coliform TMDL Report

Figure 2.03: Redwood River Watershed Counties and Sample Watersheds

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2.3 Land Use

The Redwood River corridor has several different land uses. The lower reach from Lake Redwood to the city of Marshall is on a lowland plain with a valley one-eighth to one-quarter mile wide and twenty-five to fifty feet deep. Bank vegetation includes a twenty to one-hundred foot belt of hardwoods and willows bordering row crops and pasture. The second reach of the river, from the inlet of the diversion channel in Marshall upstream to the city of Russell has a deep, narrow valley and heavily forested terrain. Trees include oak, sugar maple, basswood, and elm. A definite open flood plain forms only near the town of Lynd and downstream. The third reach of the river, extending from Russell upstream to Florence has narrow, short floodplains surrounded by rolling terrain. Immediate banks and floodplains are twenty-five to forty percent forested and sixty to seventy-five percent grasses, sedges, and small shrubs. The upper reach is a series of gullies, ditches, marshes, and small lakes. Vegetation consists of grasses, sedges, and small scattered shrubs and trees. Flow is confined to spring runoff and storm events at the headwaters of the Redwood River. The entire Redwood River watershed has 83 percent (approximately 374,382 acres) of the land in cultivation, 7.3 percent of the land in grassland, 1.5 percent in water, and 0.465 percent in wetlands. The remainder of the land is in forest, farmsteads, gravel pits, rural development, and other land uses. For detailed information by county and of the watershed as a whole, refer to Table 2.02, Table 2.03, and Table 2.04. Land use data in this report is from the Land Management Information Center (LMIC), now known as the Minnesota Geospatial Information Office (MNDNR filename: lulxcpy3). The data set was originally assembled in the early 1990’s. This data set was verified and delineated using airphotos. The data is in vector format, which is to say, each land use classification is limited to the only area that fulfills the definition of that particular land use. Example: a farm residence would be surrounded by cultivated land, the area of lawn and farm buildings (house, barn, etc.) would be classified as rural residence and a wind break of trees would be deciduous forest. The land use classified as being covered under MS4 permits was determined using a different data set. This data set, the National Land Cover Dataset 2001(NLCD 2001, MNDNR filename: nlcd_mncovra2), was also verified and delineated using airphotos. The main difference between these two data sets is that the NLCD data set is in raster format. Raster data is classifying blocks of land thirty meters by thirty meters into one dominant land use within that area even if only fifty one percent of the area in question fits that class and the other forty nine percent could be classified as a different land use. This data set is not as precise for determining overall land use within a watershed. This (NLCD 2001) data set was used for determining MS4 area because that was the method used by the Minnesota River Turbidity TMDL for determining MS4 area. Pollutant reductions required by the Minnesota River Turbidity TMDL were determined by running different modeling scenarios using the HSPF model which requires raster data for modeling. This raster data requirement and the desire to remain consistent with reports that already model the watershed covered by this study, has led the authors to utilize two different data sets within this report for determining land use. The LMIC data set was used for determining general land use and the NLCD 2001 data set was used to determine developed area covered by MS4 permits.

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Table 2.02: Redwood River Watershed Land Use by County in Acres and Percentages Entire Yellow Watershed Land Use Pipestone Murray Lincoln Medicine Lyon Redwood Acres % Acres % Acres % Acres % Acres % Acres % Acres % 1.78 0.00 Coniferous Forest 1.78 0.01 374,382.05 82.97 Cultivated Land 13,243.22 79.61 7,757.50 82.03 66,483.97 77.09 13,670.06 94.66 158,175.30 80.60 115,051.99 89.72 11,562.91 2.56 Deciduous Forest 287.33 1.73 122.29 1.29 2,067.42 2.40 152.05 1.05 5,414.46 2.76 3,519.35 2.74 Exposed Soil, Sandbars, & Sand 38.06 0.01 Dunes 14.00 0.01 24.06 0.02 5,550.21 1.23 Farmsteads & Rural Residences 207.24 1.25 88.38 0.93 1,230.68 1.43 157.29 1.09 2,474.30 1.26 1,392.33 1.09 32,871.35 7.28 Grassland 2,256.60 13.57 1,093.46 11.56 8,913.57 10.34 64.04 0.44 17,504.73 8.92 3,038.94 2.37 Grassland-Shrub-Tree 392.17 0.09 (Deciduous) 13.35 0.08 2.02 0.02 77.27 0.09 0.57 0.00 205.56 0.10 93.41 0.07 260.94 0.06 Gravel Pits & Open Mines 0.55 0.00 32.54 0.04 173.04 0.09 54.81 0.04 689.68 0.15 Other Rural Developments 26.73 0.16 2.48 0.03 165.02 0.19 20.24 0.14 318.65 0.16 156.57 0.12 155.76 0.03 Rural Residential Development 49.37 0.06 106.39 0.05 394.50 0.09 Transitional Agricultural Land 12.93 0.08 191.92 0.22 167.51 0.09 22.15 0.02 6,799.56 1.51 Water 24.62 0.15 37.98 0.40 3,692.90 4.28 12.66 0.09 2,445.43 1.25 585.96 0.46 2,100.18 0.47 Wetlands 44.44 0.27 115.84 1.22 438.57 0.51 1.32 0.01 1,203.14 0.61 296.87 0.23 16,050.34 3.56 Other (Developed) 518.13 3.11 236.41 2.50 2,899.38 3.36 361.03 2.50 8,034.73 4.09 4,000.67 3.12

451,249.49 100.00 Totals 16,635.15 100.00 9,456.36 100.00 86,242.61 100.00 14,441.05 100.00 196,237.22 100.00 128,237.11 100.00

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Table 2.03: Redwood River Land Use by Impaired Reach

Land use Percentages

Impaired Reach Description Drainage Water/ Residential (Section #) Area (mi2) Cult. Grass* Forest Wetland / Urban** Other*** Clear Creek to Redwood River (5.3.1) Redwood Lake 32.52 85.0% 5.3% 3.7% 1.1% 4.9% 0.08% Threemile Creek Redwood River (5.3.2) to Clear Creek 89.73 89.0% 3.5% 2.6% 0.8% 4.0% 0.09% T111 R42W S33 west line to Redwood River (5.3.3) Threemile Creek 308.41 76.3% 11.4% 2.9% 3.2% 6.1% 0.09% Headwaters to Threemile Creek (5.3.4) Redwood River 121.92 84.0% 8.5% 1.9% 1.6% 4.0% 0.06%

Table 2.04: Cumulative Land Use in the Redwood River Watershed

Cumulative Land Use Percentages Sections or Sub- TMDL Drainage Water / Residential/ sheds Contributing Section # Area (mi2) Cultivated Grass* Forest Wetland Urban** Other*** Redwood All Sections River Contribute Watershed 705.08 83.0% 7.5% 2.6% 2.0% 5.0% 0.07%

5.3.1, 5.3.2, 5.3.3, 5.3.4, Clear Creek 5.3.1 635.98 82.0% 8.1% 2.5% 2.2% 5.1% 0.07%

5.3.2, 5.3.3, 5.3.4 5.3.2 520.05 80.3% 9.4% 2.6% 2.4% 5.2% 0.08%

5.3.3 5.3.3 308.41 76.3% 11.4% 2.9% 3.2% 6.1% 0.09%

5.3.4 5.3.4 121.92 84.0% 8.5% 1.9% 1.6% 4.0% 0.06% Flow Clear Creek Correction 83.41 91.9% 1.5% 1.5% 1.0% 4.1% 0.00% Flow Ramsey Creek Correction 66.44 93.9% 0.7% 1.6% 0.0% 3.8% 0.03%

*Grass includes: “Grassland”, “Grassland-Shrub-Tree” and “Transitional Ag. Land”

** Residential/Urban includes: “Other (Developed)”, “Farmsteads & Rural Residences”, “Rural Residential Development” and “Other Rural Developments”

***Other includes: “Gravel Pits and Open Mines” and “Exposed Soil, Sandbars & Sand Dunes”

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2.4 Temperature

Figure 2.04 presents the average monthly high, low, and mean temperatures at Redwood Falls, MN. Ice-out conditions in the Redwood River typically occur in late March or early April with smaller tributaries usually following. Warmest air temperatures reach their peak in July, while the warmest water temperatures are usually in late July and August.

Figure 2.04: Average Monthly Temperatures Average Monthly High, Low, and Mean Temperature Avg. High Redwood Falls, MN (1971-2000 data) Avg. Low 90 Mean 80 73.5 70 69.6 71.0 61.8 60 60.4

50 47.1 49.3 40 32.3 30 32.2

20 20.0 18 . 1 13 . 1 10

0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

2.5 Precipitation

The Redwood River watershed averages 28.4 inches annually. A little over 80 percent of precipitation occurs between the months of April and October. Figure 2.05 presents the composite average monthly precipitation values for four towns across the Redwood River watershed. Figure 2.06 uses the same data set as Figure 2.05 and summarizes the data by year over the 1977 to 2006 time frame. Figure 2.07 uses the Southwest Minnesota Regional precipitation summary. The Southwest Minnesota precipitation region covers the nine counties in southwest Minnesota (Cottonwood, Jackson, Lincoln, Lyon, Murray, Nobles, Pipestone, Redwood and Rock). This region covers almost 97% of the Redwood River watershed, but at the same time, the Redwood River watershed makes up only 11.5% of the Southwest Minnesota region covered by this precipitation summary.

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Figure 2.05: Average Monthly Rainfall

Figure 2.06: Annual Precipitation – point summary (1977-2006)

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Figure 2.07: Annual Precipitation – regional summary (1977-2006)

2.6 Stream Flow Dynamics

Figure 2.06 displays the mean monthly flow for the Redwood River in Redwood Falls (USGS gage #05316500) for the 1977 to 2006 time frame and Figure 2.07 displays the mean monthly flow for the same gage, but for the previous 30 year period (1947-1976). Figure 2.08 shows the percent of yearly flow by month for the 1977 to 2006 time frame and Figure 2.09 displays the percent of yearly flow by month for the previous 30 year period (1947 to 1976). April has higher flows, on average due to snowmelt and overland runoff while June, having the most precipitation, has the second highest mean monthly flow. Flow is measured in cubic feet per second (cfs).

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Figure 2.06: Mean Monthly Flow; Redwood Falls 1977-2006 (RR1 – S001-679)

Figure 2.07: Mean Monthly Flow; Redwood Falls 1947-1976 (RR1 – S001-679)

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Figure 2.08: Monthly Distribution of Flow, Redwood Falls 1977-2006 (RR1 – S001-679)

Figure 2.09: Monthly Distribution of Flow, Redwood Falls 1947-1976 (RR1 – S001-679)

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3.0 Description of Applicable Water Quality Standards and Assessment Procedures

3.1 Classification and Beneficial Uses

The TMDL evaluation is a method of addressing and assessing the waters that exceed the state water quality standard for turbidity. All waters of Minnesota are assigned classes, based on their suitability for the following beneficial uses (Minn. Rules part 7050.0200): Class 1 – Domestic consumption Class 2 – Aquatic life and recreation Class 3 – Industrial consumption Class 4 – Agriculture and wildlife Class 5 – Aesthetic enjoyment and navigation Class 6 – Other uses Class 7 – Limited resource value

All surface waters of the state that are not specifically listed in Chapter 7050 and are not wetlands, which include most lakes and streams in Minnesota, are classified as Class 2B, 4A, 5 and 6 waters (Minn. R. ch. 7050.0430).

According to Minn. R. ch. 7050.0220-0227, the designated beneficial use for the different use classes is as follows: Class1B: For domestic consumption following approved disinfection, such as simple chlorination or its equivalent. Class 2A: Aquatic life support refers to cold water sport or commercial fish and associated aquatic life, and their habitats. Recreation support refers to aquatic recreation of all kinds, including bathing, for which the waters may be usable. Class 2A also is protected as a source of drinking water. Class 2B: Aquatic life support refers to cool or warm water sport and commercial fish and associated aquatic life, and their habitats. Recreation support refers to aquatic recreation of all kinds, including bathing. This class of surface water is not protected as a source of drinking water. Class 2C: Aquatic life support and recreation includes boating and other forms of recreation for which the water may be suitable (i.e., swimming). Class 2C waters may also support indigenous aquatic life, but not necessarily sport or commercial fish. Class 3B: General industrial purposes, except for food processing, with only a moderate degree of treatment. Similar to Class 1D waters of the state used for domestic consumption.

Relative to the turbidity standard, all of the waters covered in this report are either Class 2B, 3B, 2C.

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3.2 Applicable Minnesota Water Quality Standards

This TMDL addresses exceedences of the water quality standard for turbidity. According to Minn. R. ch. 7050.0222 subp. 4 and 5, turbidity water quality standard for Class 2B and 2C waters states that turbidity readings shall not exceed 25 nephelometric turbidity units, hereafter referred to as NTUs. The impaired reaches of the Redwood River covered by this TMDL are classified as 2B and 7 waters. The designated beneficial use for 2B waters (the most protective use class) is as follows:

Class 2 waters, aquatic life and recreation. Aquatic life and recreation includes all waters of the state which do or may support fish, other aquatic life, bathing, boating or other recreational purposes and where quality control is or may be necessary to protect aquatic or terrestrial life or their habitats, or the public health, safety or welfare.

Turbidity in water is cause by suspended sediment, organic material, dissolved salts and stains that scatter light in the water column making the water appear cloudy. Excess turbidity can degrade aesthetic qualities of water bodies, increase the cost of treatment for drinking or food processing uses and can harm aquatic life. Aquatic organisms may have trouble finding food, gill function may be affected and spawning beds may be covered.

Suspended Solids Concentration as the Surrogate Measure for Turbidity

Much of the Redwood River Watershed is cultivated cropland. Soil erosion from cropland contributes to the sediment load in streams. It is widely accepted that sediment sources in streams in such settings are comprised of sediment that originates from eroded soil, erosion of stream-bank sediments and re-suspension of stream bed material. (Colby, 1963). To better understand the relative contributions from these sources of sediment in the Minnesota River Basin, the Minnesota Pollution Control Agency (MPCA), in writing the turbidity TMDL for Minnesota River, determined various rates of contributions for all three potential sediment sources. Using total suspended solids concentrations (TSS) and turbidity data that was collected by the RCRCA and MPCA, a surrogate measure of the 25 NTU standard was calculated as TSS for this TMDL.

Numeric Water Quality Target

Turbidity cannot be converted into loads because it is a dimensionless unit. To use the 25 NTU turbidity standard in a load allocation scenario, a relationship between turbidity and TSS was developed. Using total suspended solids (TSS) allows the calculation of loads based on concentration. RCRCA has conducted field sampling on the Redwood River since the 1990’s. Testing for TSS and Turbidity on the same sample has been ongoing since 2003. The turbidity measurements were taken from the same sample as the TSS, these are defined as “paired” measurements. Using the paired turbidity and

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TSS measurements for the RR1 site on the Redwood River, a multiple regression technique was used to predict TSS based on turbidity. This regression technique results in a value of 70 mg/L of TSS for the 25 NTU equivalent. The R2 value indicates the strength of the correlation between the two variables. A fairly good correlation between TSS and turbidity is evidenced by a relatively high R2 of 0.71. The regression equation is displayed on Figure 3.03.

Degree of Impairment

Based on the available data (Appendix B) the turbidity impairment at reach monitored by sample site RR1 appears to be “major” when viewed across the entire sampling season. Slightly under half of the turbidity readings taken during the open water season were 25 NTU or higher during the period assessed to determine impairment (Table 3.01). More recent testing has resulted in a higher percentage of turbidity readings during the open water season were over 25 NTU or higher.

The other reaches covered by this report have considerably less data to draw conclusions with. Sampling locations have been added to address the lack of data along these reaches.

3.3 Impaired Assessment

Impairment assessment is based on the procedures found at: http://www.pca.state.mn.us/water/tmdl/index.html#support

Water quality data available through STORET for the most recent 10 year period is used in waterbody assessments for the 303(d) list. The MPCA uses data collected over the most recent ten year period for all water quality assessments considered for 303(d) impairments. Years of record are based on the USGS water year. Water years are from October 1 of one year through September 30 of the following year. Data for all 10 years of the period are not required to make an assessment. The 10 year period is used to provide reasonable assurance that data will have been collected over a range of weather and flow condition and that all seasons will be adequately represented.

The MPCA and RCRCA monitored the Redwood River and its tributaries for turbidity at the locations identified in the Figure 3.01. Table 1.01. as well as Table 3.03, provides summary information of the data used to determine the impairment status of the four stream reaches included in the Report.

Table 3.01 displays the data used by MPCA to assess the impaired reaches. Table 3.02 summarizes all relevant data collected by RCRCA through their stream monitoring program. Data summarized in Table 3.02 is listed in appendix B

Turbidity is a highly variable water quality measure. Because of this variability, and the use of TSS and transparency as surrogates, a total of 20 independent observations are

21 Redwood River Turbidity TMDL Report

required for a turbidity assessment. If there are observations of more than one of the three parameters in a single day, the hierarchy of consideration for assessment purposes will be turbidity, then transparency, then TSS. For a water body to be listed as impaired for turbidity, at least three observations and 10 percent of observations must be in violation of the turbidity standard. If sufficient turbidity measurements exist, only turbidity measurements will be used to determine impairment. If there are insufficient turbidity measurements, any combination of independent turbidity, transparency, and TSS observations may be combined to meet assessment criteria. Data summarized in Table 3.02 follows the guidance above with data not relevant to the listing excluded from the table.

It is important to recognize the value and necessity of including professional judgment as a “formal” step in the assessment process. Professional judgment must enter into the impairment decision making process. Professionals include the people that take water samples and measurements in the field as well as the biologists, hydrologists and statisticians that analyze the data. A professional judgment team is formed for each basin. The team is comprised of, for example, regional MPCA basin coordinators knowledgeable about local water quality issues, MPCA monitoring and data assessment staff, and staff from organizations outside the MPCA whose data were used in the assessments, if appropriate. They determine whether the data are adequate and appropriate for making statements about use-support and about causes of impairment.

Based on all the relevant information, a final impairment decision is made regarding a given water quality standard and the associated beneficial use. These decisions are based on a “weight of evidence” concept, which simply means that when all the readily available data and information are considered together, and in the appropriate context, a convincing pattern emerges on the condition of the waterbody.

The MPCA assembles the professional judgment groups and chairs the meetings; the MPCA takes responsibility for all team decisions regarding impairment. While consensus of opinion on impairment decisions is the goal, and is normally achieved, if consensus cannot be obtained, the MPCA will make the final decision.

Note that two of the reaches that are deemed to be impaired for turbidity are listed by MPCA determination with little turbidity or surrogate data. There is also one reach (AUID: 07020006-506; Clear Creek – tributary to the Redwood River) that was impaired when looking solely at the data, but was removed from the impaired list by the professional judgment group.

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Figure 3.01: Redwood River Watershed Sampling Sites

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Table 3.01: Summary of data used by MPCA for Turbidity Assessment Redwood River Assessment Summary (1996 – 2006) Impaired Reach AUID RCRCA Monitoring % of Number of Station Samples in Years of STORET ID Parameter Used Observations Violations Violation Data 07020006-509 RR1 Turbidity 50 24 48.0% 4 S001-679 07020006-503 Transparency Tube No RCRCA Site & MPCA 21 15 71.4% 1 S004-299 Determination 07020006-502 Turbidity & No RCRCA Site MPCA 3 0 0.0% 3 No STORET Site Determination 07020006-504 TC4A Turbidity 34 7 20.6% 3 S002-313 Assessment observations & violations may include composite samples

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Table 3.02: Summary of turbidity data collected by RCRCA and the Citizen Stream Monitoring Program (CSMP) at impaired reaches (2003-2009)

AUID: 07020006-509 Parameter: Turbidity Sample Site: RR1 STORET ID: S001-679 Violations Violations % > 25 Year # Samples Max Min Mean Median # > 25 NTU NTU 2009 34 400 5 43.91 33 25 73.5% 2008 23 120 4 38.00 29 14 60.9% 2007 25 150 2 52.96 48 19 76.0% 2006 20 170 5 35.55 33 11 55.0% 2005 23 160 6 41.97 24 10 43.5% 2004 14 130 6.8 37.56 15 5 35.7% 2003 6 30 4 16.67 16.5 1 16.7%

AUID: 07020006-503 Sample Site: Parameter: T-Tube CSMP1210 STORET ID: S004-299 Violations Violations Year # Samples Max Min Mean Median # < 20 cm % < 20 cm 2006 21 29 9 17.81 17 15 71.4%

AUID: 07020006-502 Parameter: Turbidity Sample Site: RWR-53 STORET ID: S001-199 Violations Violations % > 25 Year # Samples Max Min Mean Median # > 25 NTU NTU 2009 12 53 2.3 11.21 6.2 1 8.3%

AUID: 07020006-502 Parameter: Turbidity Sample Site: Marshall STORET ID: S003-702 Violations Violations % > 25 Year # Samples Max Min Mean Median # > 25 NTU NTU 2009 12 40 2.3 9.83 4.4 2 16.7%

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AUID: 07020006-504 Parameter: Turbidity Sample Site: TC4A STORET ID: S002-313 Violations Violations % > 25 Year # Samples Max Min Mean Median # > 25 NTU NTU 2009 15 140 7.2 29.95 26 8 53.3% 2008 17 120 8 37.94 37 11 64.7% 2007 13 150 10 36.38 25 6 46.2% 2006 14 90 4 27.00 27 8 57.1% 2005 15 39 8 18.40 16 2 13.3% 2004 9 20 7 12.33 11 0 0.0% 2003 4 25 6 15.75 16 0 0.0% Grab samples only, no composite data included. Duplicate data averaged before used in these calculations.

Table 3.03: Redwood River Watershed Assessment Site Descriptors

Monitoring Stations % of data Year River Assessment Used for in Years of Reach Description listed Unit ID Assessment violation Data

T111 R42W S33 Redwood west line to MPCA River Threemile Cr 02 07020006-502 Determination 0% ’98 Redwood Three Mile Creek River to Clear Creek 10 07020006-503 S004-299 71.4% ‘06 Three Mile Headwaters to Creek Redwood River 04 07020006-504 S002-313 20.6% ‘97-‘05 Redwood Clear Creek to River Redwood Lake 02 07020006-509 S001-679 48.0% ‘97-‘05

Table 3.04 Redwood River Watershed Sampling Sites for Future Monitoring of Impaired Reaches

Sample Site TMDL River Assessment Monitoring Stations Name Section # Reach Description Unit ID Used by RCRCA

Redwood Clear Creek to RR1 5.3.1 River Redwood Lake 07020006-509 S001-679

Redwood Three Mile Creek to CSMP1210 5.3.2 River Clear Creek 07020006-503 None

Redwood T111 R42W S33 west RWR-53 5.3.3 River line to Threemile Cr 07020006-502 S001-199

Redwood T111 R42W S33 west MARSHALL 5.3.3 River line to Threemile Cr 07020006-502 S003-702

Three Mile Headwaters to TC4A 5.3.4 Creek Redwood R 07020006-504 S002-313

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3.4 Description of Turbidity and Development of TSS Surrogates

Turbidity is a measurement of the clarity of water, determined by how much light is absorbed and scattered in a water sample (MPCA, 2005). It is not a direct measure of pollutant mass. It is caused by the presence of suspended material such as clay, silt, sand, finely divided organic matter, bacteria, plankton and other microscopic organisms. However, because light scatter and absorption is strongly affected by particles suspended in the water, there is a strong relationship between turbidity and the commonly used mass-based water quality parameter total suspended solids (TSS). For this reason, and because mass loads are needed for TMDL calculations and allocations, TSS is commonly used as a surrogate for turbidity.

Turbidity is a dimensionless unit and cannot be converted into loads. To use the 25 NTU turbidity standard in a load allocation scenario, a relationship between turbidity and the total suspended solids concentration (TSS) was developed. There are a number of factors that need consideration in the work to establish a TSS surrogate for the turbidity water quality standard. These include the effect of suspended particle size and concentration on turbidimeter response, parametric data analysis assumptions, and differences between meters measuring turbidity.

In order to minimize the variability found in the measurement of turbidity, the data used to develop the TSS surrogate was filtered to only include data sets where the turbidity was less than 40 NTU and the TSS was greater than 10 mg/L following the MPCA Turbidity TMDL Protocol (MPCA, 2007).

Using the raw data values and plotting the data using a linear and a power regression, results in TSS surrogate values of 65.3 mg/L with an r-squared value of 0.61 for the former and 60.3 mg/L with an r-squared value of 0.71 for the latter regression technique (Figure 3.01).

To use linear regression in the work, a data transformation was needed to meet the assumption of the data being normally distributed for the appropriate use of the parametric statistical method. A natural log transformation of the data was found to provide a reasonably normal distribution of the data. Using the natural log transformation as opposed to a transformation of another sort was chosen because much of the related regression work within the MPCA has been performed using a natural log transformation.

The Redwood and Cottonwood River turbidity and TSS data were analyzed both separately and as a combined group, based on similar geology and land use.

27 Redwood River Turbidity TMDL Report

The TSS surrogate value for 25 NTU was computed by using the regression equation to solve for TSS when turbidity equals 25 NTU. The initial (transformed) surrogate value for the Redwood River is 67 mg/L of TSS with an r-squared value of 0.71 (Figure 3.03). When the two watersheds were grouped for analysis the surrogate value was determined to be 64 mg/L of TSS with an r-squared value of 0.75.

Retransforming log-transformed regression estimates to provide a “raw” data value estimate results in a retransformation bias given that the logarithmic transformation is nonlinear. The estimates are biased on the low side. A bias correction method known as Duan’s smearing estimator was applied to the dataset, resulting in a correction value of 4.5 for the Redwood River. This creates a bias adjusted value of 71.4 for the Redwood River. When this correction method is applied to the grouped data for both the Redwood and Cottonwood Rivers, the correction value is 3.7. The correction value combined with the group value of 64.2 results in a biased adjusted value of 67.8 for the group value. Individual rivers and grouped river values were analyzed statistically to ensure the values were valid at the 95% confidence interval. Discussions regarding the data and the statistical analysis process were held within the MPCA Minnesota River Turbidity TMDL Technical Team and a surrogate value of 70 mg/L of TSS (Figure 3.04) was adopted for the Redwood and Cottonwood Rivers. (MPCA, 2008)

Figure 3.02: TSS – Turbidity Regression (2003-2007)

28 Redwood River Turbidity TMDL Report

Figure 3.03: TSS – Turbidity Log-transformed Regression (2003-2007)

29 Redwood River Turbidity TMDL Report

Figure 3.04: TSS Surrogate Value at 95% Confidence Interval

3.6 MPCA Non-degradation Policy Non-degradation is an important component of water quality standards in Minnesota. MPCA policy distinguishes non-degradation for all waters from non-degradation for Outstanding Resource Value Waters (ORVW), as follows:

Minn. R. ch 7050.0185, subp. 1. Non-degradation for All Waters. The potential capacity of the water to assimilate additional wastes and the beneficial uses inherent in water resources are valuable public resources. It is the policy of the state of Minnesota to protect all waters from significant degradation from point and nonpoint sources and wetland alterations, and to maintain existing water uses, aquatic and wetland habitats, and the level of water quality necessary to protect these uses.

3.7 Trends in TSS Surface Water Quality

Turbidity and TSS both tend to reach peak values for the year during the snowmelt and spring storm season (April to June). TSS values tend to remain under the water quality standard most of the remainder of the season with standard violations occurring in response to large rain events that have significant impact on flow.

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4.0 Description of Turbidity and Its Sources

4.1 Turbidity Description

Turbidity can be caused by various constituents including dissolved organic compounds (stains), suspended organic materials (algae, other organisms, plant and soil matter) and suspended inorganic matter (clay, silt or sand). In the Redwood River and its tributaries, suspended inorganic particles are the primary contributors of turbidity, especially during high flows when turbidity levels are often elevated. Suspended organic matter can also be a significant cause of turbidity, particularly during low flow conditions.

4.2 Turbidity Sources

The purpose of this section is to describe the potential sources of turbidity within the Redwood River watershed. An understanding of the sources and processes that cause elevated turbidity levels is necessary for the development of an effective implementation plan to reduce these impairments.

TSS components can be derived from many different source types and locations within a basin. Some sources are external to the channel and derived from the contributing watershed area. Other sources are internal and originate within the river channel. Most point and nonpoint sources are considered to be external since they exist outside of the channel and yet contribute TSS to the waterbody. Internal sources are components (and associated processes) that occur within the channel. Internal sources would include streambanks, streambeds, bluffs and possibly floodplains, all of which are potential sediment sources to a river.

4.3 Definitions

The areas adjacent to the Redwood River and its tributaries are largely made up of bluffs, streambanks and floodplains.

31 Redwood River Turbidity TMDL Report

Streambanks

Streambanks are ridges of material which generally occur parallel to the river channel. They are typically composed of material which was deposited by the water in the river channel. Streambanks are dynamic and their size, shape and composition, often change between seasons and, in some cases, between storm events.

Floodplains

Floodplains are generally flat lying areas which occur on the side of a streambank opposite the river. They are also composed of material which was deposited by river water, however the material is only reworked during flood events when the river level rises above the height of the streambank and water covers the floodplain.

Bluffs

Bluffs are steep exposures of material not deposited by the present day river. Bluffs may be located immediately adjacent to the river, or can be set back from the channel at the margins of the river valley.

4.4 Processes

This section will describe the processes by which these features supply sediment to the river channels. Streambanks and floodplains will be discussed together since they typically occur in the same setting. Since bluffs often extend to heights above the highest flood stage, there are no floodplains behind bluffs. Bluffs may be adjacent to the river, in lieu of a streambank.

Streambanks and Floodplains

Streambanks and floodplains are, for the most part, composed of material that was “reworked” or deposited by the water conveyed in the river. Under almost all flow conditions, the water in the channel is in direct contact with the sediment at the face of the streambed (bottom of channel) and, to varying degrees, the streambanks (sides of channel). Floodplain material is only reworked when high flows cause the river level to rise above the streambanks and the floodplains themselves become inundated.

When sediment from the streambed, streambanks and floodplains is in direct contact with water, there is a potential for sediment entrainment or erosion and subsequent transportation. Erosion caused by water moving within a river channel is generally called hydraulic or fluvial erosion. The movement of water along the fluid/sediment interface generates a shear stress. This shear stress is largely a function of the water velocity at that interface, which is, in turn, largely dependent on the volume of water moving through the river reach as well as the longitudinal slope of the reach. When shear stresses are very low the smallest particles, such as clays, will settle out and be deposited. As the water velocity and the associated shear stresses increase, the river

32 Redwood River Turbidity TMDL Report will be able to keep more material in suspension and thus material entering a river reach will stay entrained and will not be deposited. At the highest flows, shear stresses will be great enough not only to keep suspended sediment entrained, but to also lift or erode additional sediment particles off the surface of the beds, banks or floodplains. This particle entrainment will increase the amount of TSS in the water column which will also increase turbidity.

Sediment can be both deposited on and eroded from streambeds, banks and floodplains, thus these features are both sediment sinks and sources. It is natural for rivers to meander, a process that couples erosion on the outer bend (cutbank) while simultaneously depositing sediment on the inner bend (point bar). Since rivers are dynamic systems, it is important to consider the integrated net effect of streambeds, banks and floodplains in an overall watershed sediment budget, since on the local scale they are both sites of visually observable deposition and erosion. River systems where the channels are actively widening or downcutting are net sources of sediment to the channel. The beds, banks and floodplains of these degrading river systems have the potential to be significant net sources of sediment and turbidity.

The downcutting process occurring in degrading river systems is visible in the last few miles of the Redwood River, as the river moves into the Minnesota River Valley. This reach of the Redwood River is covered by the Minnesota River Turbidity TMDL and will not be covered in this report. The dam at Lake Redwood prevents this downcutting process from moving further upstream in the watershed and thus is not a dominate process in the Redwood River Watershed.

Bluffs

Bluffs are steeply sloping exposures of material which were not deposited by water in the river channel. The few bluffs we have in the Redwood River Watershed are made up of sub-horizontal layers of glacially deposited sediment.

Bluff erosion may be hydraulically driven if the bluff bounds the river channel. Bluffs that exist on the outer bend of a meander may experience shear stresses from the river channel that can erode the submerged portion of the bluff. These stresses may result in the toe of the bluff being removed or undercut and the upper portion of the bluff now lacks foundational support. This hydraulically driven undercutting will often be followed by a gravity driven process know as slumping. Slumping usually results from a detached block of the bluff remaining mostly undeformed and slumping downward around a rotational axis. Although slumping is primarily a gravity-driven process, other factors such as the weight of additional burden near the edge of the bluff, freeze-thaw cycles and changes in pore pressures due to groundwater seepage can accelerate collapse.

While it is possible for slumping to occur without the antecedent undercutting, it is the combination of the two processes that are particularly relevant to sediment production and turbidity pollution. Bluff faces that do not bound a river cannot be undercut by

33 Redwood River Turbidity TMDL Report channel shear stresses. The faces of these bluffs can fail due to slumping or a slower deformational process called creeping. However, when bluffs not adjacent to the river fail, the falling material does not land in the river channel. This material may eventually contribute to increased turbidity at a later time, but it must first be carried to the channel. This transportation of material is most likely accomplished by overland runoff.

Bluff material that falls into the river is typically not an immediate source of turbidity. Generally the bluff material is not greatly deformed and remains as one or a few discrete masses. Shear stresses and chemical dissolution in the river will eventually break the blocks into smaller pieces and separate the individual sediment particles. The length of this process depends on the cohesiveness of the bluff material. Bedrock is often lithified or cemented and therefore very resistant to erosion. Additionally, much of the glacial material in the bluffs is very well consolidated due to the prehistoric overburden of massive ice sheets. Therefore, the collapse of bounding bluffs can be significant source of (consolidated) sediment to the drainage system, although the impact on turbidity levels is likely metered over time as the consolidated masses break down.

Ravines

Ravines are v-notched erosion features typically occurring at the boundary of flat lying uplands and steep-sloping surfaces, such as bluffs or other steep valley walls. The terms “ravine” and “gully” are often used interchangeably, although many refer to a gully as a smaller linear depression which can be filled by common tillage equipment. Ravines are usually referred to as larger, more permanent features with a depth of .5 to 30 meters (Poesen, 2003)

Ravines can be eroded by water moving through their channel, similar to streambanks (hydraulically driven); as well as by rotational failure of their sides, similar to bluffs (gravitationally driven). The primary driver of ravine erosion is overland runoff which moves through rills and then is ultimately concentrated into one ephemeral channel, cutting downward into the steep face. Ravines are unique because they funnel water and sediment from larger upland areas over the edge of a steep surface. This funneling allows the ravines to incise vertically and elongate longitudinally.

Some actively eroding ravines in the Redwood River watershed are a source of sediment.

The distribution of bluffs and ravines is controlled by the migration of knickpoints. Knickpoints define abrupt breaks in slope. The largest knickpoint in the Redwood River watershed is in the last few miles as the river downcuts in an attempt to achieve a new longitudinal gradient in equilibrium with a low base level determined by the Minnesota River. The reach of the river affected by this knickpoint downcutting is covered by the Minnesota River Turbidity TMDL. This process is not as strong in the reaches covered by this TMDL report.

34 Redwood River Turbidity TMDL Report

Uplands

Generally, uplands are the broad flat-lying areas that comprise most of the watershed. Unlike floodplains, most uplands are not inundated with standing water during flood conditions and they are not always located in close proximity to a waterbody. Uplands are divided into pervious and impervious areas. The majority of the impervious areas are found in urban areas. The pervious areas are subdivided in terms of land use. The dominant land use in the Redwood River watershed is row croplands or fields. Other land uses such as other types of agriculture, forests, wetlands, grasslands and urban land uses are also found.

Land areas can supply sediment to receiving waters through rill and sheet erosion processes or gully scour. The erosion of sediment associated with rill and sheet processes has two parts. First, sediment particles must become detached from the soil matrix and made available for transport. Second, the particle is carried away from the surface by overland flow. Gully scour involves the removal of undetached sediment from the soil matrix by overland flow.

Land use has a profound impact on the degree to which erosive processes can effect a particular surface. For example, land which has well-developed vegetative cover will intercept drops of rainfall, whereas rainfall on bare land can detach sediment particles from the soil matrix. Well developed vegetative cover can impede the movement of water on the land surface, while runoff on bare land can move freely across the surface and allow rills or gullies to form. Water moving in the rills and gullies can transport sediment off the land. Additionally, open tile intakes can transport sediment to a waterway through drainage tile.

Ditches/Channelization

Ditches and/or straightened portions of a waterway are not turbidity sources per se, but are important factors to consider when evaluating excess stream turbidity. Such watercourses are shorter than the natural channel and, thus, are steeper in gradient. As such, they generally exhibit higher velocities and higher peak flows. This increase in gradient also limits access to the floodplain. Therefore, the energy of the stream is confined to the channel. Straightened channels also exhibit a tendency to revert to a meandering condition. The net result is an increased potential for bank erosion. The main channel of the Redwood River was extensively channelized and straightened between the city of Marshall and Seaforth. This stretch of the river is now known as Judicial Ditch Thirty Seven (JD37).

Stormwater Runoff

Stormwater runoff comes from cities, towns, roads, homesteads, etc. Runoff can contribute to excess turbidity directly via sediment and phosphorus delivery and indirectly via increased runoff of water leading to increased bank and bed erosion.

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Impervious surfaces (roads, parking lots, roofs, etc.) can be problematic because most of the water runs off, leaving little opportunity for storage.

In 1987, the federal Clean Water Act was amended to include provisions for a program to address stormwater runoff. There are currently two regulated MS4 communities in the Redwood River watershed, but only one of them discharges to a stretch of the Redwood River covered by this report. Growth and development in these communities is not expected to be significant.

Erosion from construction sites can also be a source of sediment. The MPCA issues permits for any construction activities disturbing:

• One acre or more of soil; • Less than one acre of soil if that activity is part of a “larger common plan of development or sale” that is greater than one acre; or • Less than one acre of soil, but the MPCA determines that the activity poses a risk to water resources.

Although stormwater runoff at construction sites with inadequate runoff controls can be significant on a per acre basis, the number of projects per year in this rural watershed is relatively small. Therefore, this source appears to be a minor turbidity source.

Industrial discharge permit holders in the watershed do not appear to represent a TSS loading concern in this watershed. For the purpose of the TMDL, industrial discharges are lumped with construction stowmwater to calculate a wasteload allocation.

Urban and developed land, including cities, small towns and roads encompasses roughly five percent of the area.

Wastewater

Wastewater and water treatment facilities discharge total suspended solids. Relative to turbidity and TSS, each facility has a National Pollutant Discharge Elimination System (NPDES) permit with a discharge limit of either 30 mg/L or 45 mg/L TSS, as well as average and maximum daily loading limits per calendar week and month. The effluent limits are below the turbidity surrogate value of 70 mg/L TSS for the Redwood River watershed. Therefore, because wastewater effluent limits are below the turbidity surrogates, they are deemed not to cause or contribute to the violation of the turbidity standards. Any future new or expanded discharges would be permissible provided that the limits are below the surrogate value. Table 4.01 lists permitted wastewater treatment facilities.

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Table 4.01: Redwood River Watershed Permitted WWTF

TSS Discharge WLA System Sub- Limit TSS WWTF Type Permit No. watershed County (mg/L) tons/day Population2 GHENT WWTP Pond MNG580121 Three Mile Creek Lyon 45 0.06 315 LYND WWTP Pond MNG580030 Middle Redwood Lyon 45 0.06 346 MARSHALL WWTP Cont. Discharge MN0022179 Middle Redwood Lyon 30 0.56 12,735 MILROY WWTP Pond MNG580124 Clear Creek Redwood 45 0.05 271 RUSSELL WWTP Pond MNG580062 Middle Redwood Lyon 45 0.11 371 RUTHTON WWTP Pond MNG580105 Upper Redwood Pipestone 45 0.07 284 TYLER WWTP Pond MNG580116 Upper Redwood Lincoln 45 0.20 1,218 VESTA WWTP Pond MNG580043 Lower Redwood Redwood 45 0.05 339 1.16 15,879

2United States Census 2000

Unsewered Communities Table 4.02: Redwood River "Unsewered" Communities CITY COUNTY SUB-SHED POPULATION BURCHARD1 Lyon Upper Redwood 30 FLORENCE2 Lyon Tyler Creek 46 GREEN VALLEY1 Lyon Middle Redwood 170 SEAFORTH2 Redwood Lower Redwood/Clear 77 THOMSONBURG1 Lincoln Upper Redwood 20 1Estimated Population 2United States Census 2000

The population in the unsewered communities in the Redwood River watershed is nearly 350 people Table 4.02. Two of the small hamlets on this list are not incorporated or have been deemed low priority. As of 2007, the city of Florence was working on upgrading to Subsurface Septic Treatment Systems (SSTSs) by July 2008 and Lyon County was working on a plan for the city of Green Valley. The city of Seaforth is putting plans together for a pond system which should be on line soon.

Urban and Rural Stormwater Several of the unsewered communities are combined sewer and stormwater systems. These can be sources of sediment. Newer urban development often includes stormwater treatment such as sedimentation basins, infiltration areas, and vegetated filter strips. Marshall and Redwood Falls are the two cities in the watershed, which are required to have a Municipal Separate Storm Sewer System (MS4) permit. The MS4

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permit requires a range of actions that will ultimately reduce the impact of stormwater from the community to downstream water bodies. Smaller communities or even rural residences not covered under MS4 permits may still need to take action to reduce stormwater and associated sediment runoff.

Subsurface Septic Treatment Systems The number of failing (includes imminent threats to public health) Subsurface Sewage Treatment Systems (SSTS) was determined from using the actual number of SSTS reported by each county to MPCA (2006 data set). The number of SSTS attributed to the Redwood River watershed was generated by multiplying the percentage of the county in the watershed by the number of SSTS in the county. This was done for each reach in the watershed. Each county had varying levels of “failing” systems, and this was taken into account for each county within a reach. Using MPCA records and the analysis method described above, it was determined there were 1,948 SSTS in the Redwood River Watershed (including seasonal and non-residential), of which, 1,051 were designated as failing. Of those 1,051 failing systems, 334 of those were estimated to be imminent threats to public health (ITPH). For the purpose of this report, a straight- pipe system, a system that directly discharges into surface waters, is considered an imminent health threat as defined below. SSTS sediment loads are minor contributors, but the nutrients discharged from failing or ITPH systems may increase turbidity via algae growth.

A SSTS that fails to protect groundwater is defined as “failing”. At a minimum, a system that is failing to protect groundwater is a system that is a seepage pit, cesspool, drywell, leaching pit, or other pit; a system with less than the required vertical separation distance (between the system and groundwater level) or a system not abandoned in accordance with state law (Rule: 7080.2500)

A SSTS system that is not protective of public health and safety is defined as imminent threats to public health (ITPH). At a minimum, a system that is an imminent threat to public health of safety is a system with a discharge of sewage or sewage effluent to the ground surface, drainage systems, ditches, storm water drains or directly to surface water; systems that cause a reoccurring sewage backup into a dwelling or other establishment; systems with electrical hazards; or sewage tanks with unsecured, damages, or weak maintenance hole covers.

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5.0 TMDL Development for the Redwood River Watershed

5.1 Approach to Allocations Needed to Satisfy the TMDLs

The TMDLs developed for the four reaches in this report consists of four main components: Load Allocations (LA), Wasteload Allocations (WLA), Margins of Safety (MOS), and Reserve Capacity (RC) as defined in Section 1.0. The WLA includes four sub-categories: Permitted wastewater treatment facilities, communities subject to Stormwater MS4 NPDES permit requirements, livestock facilities requiring NPDES permits, and “straight pipe” septic systems. As additional data become available after US EPA approval of this TMDL, WLAs for individual permitted sources may be modified, provided the overall WLA does not change. Modifications in individual WLAs will be public noticed. The LA, reported as a single category, includes nonpoint sources described in the previous section. Examples include erosion from banks, bluffs, ravines, as well as sediment runoff from farm fields, pastures, and smaller non-NPDES permitted feedlots, runoff from smaller non-permitted MS4 communities, and sediment contributions from natural sources and processes. The third component, MOS, is the part of the allocation that accounts for uncertainty that the allocations will result in attainment of water quality standards. Lastly, RC is the portion of the total load used to account for growth in the area.

The four components (WLA, LA, MOS, and RC) were calculated as average total daily load of suspended solids. The daily loading of sediment was calculated for each of a series of five flow zones ranging from low flow to high flow. Partitioning the daily sediment loads between five flow regimes is referred to as the duration curve approach in this Report and is the methodology created by Bruce Cleland (Cleland, 2002; MPCA, 2006)

TMDLs can be developed using any approach used by the USEPA. In Minnesota, the MPCA recommends the use of the “Duration Curve” approach for developing TMDLs. Steps used in the development of this TMDL are found in Appendix A.

The duration curve approach involved using the latest 30 year period (1977-2006) flow monitoring data from a U.S. Geological Survey gage station (USGS Station #0516500). USGS site #05316500 is located near the outlet of the Redwood River in to Redwood Lake near Redwood Falls, MN. Daily mean flow values for the site were obtained from 1977 through 2006.

Data at these sites have been very consistent and contain a good record of historical data. Site #05316500 was originally established in 1909 and daily data is available for a period during open water periods until 1913 and re-established in 1931 with daily flows during open water periods. The site reported daily flow values through the year from mid-1938 on.

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The daily flow values were sorted by flow volume, from highest to lowest to develop a flow duration curve. Figure 5.01 displays the flow duration curve for the USGS gage site which is also the Redwood River monitoring site (RR1). The chart depicts the percentage of time any particular flow is exceeded. For example, during the flow record 587 CFS was exceeded by 10 percent of daily flow values, and thus represents “high flow” conditions. A value of 11 CFS was exceeded by 90 percent of flow values and represents “low flow” conditions.

Figure 5.01: Redwood River Flow Duration Curve

Flow regimes were determined for high flow, moist, mid-range, dry and low flow conditions. The mid-range flow value for each flow regime was then used to calculate the total daily loading capacity (TDLC). Thus, for the “high flow” regime, the loading capacity is based on the monthly flow value at the fifth percentile. At this flow value, the mean monthly flow would be exceeded by five percent of all flow values in the dataset. Table 5.01 presents the flow regimes that were determined for the Redwood River gaging site, along with the flow value used to calculate the TDLC.

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Table 5.01: Flow Categories for the Redwood River at USGS Station #05316500 near Redwood Falls Flow Flow Duration Flow Flow Value Used to Calculate Condition Interval Range Daily Load Capacity High 0-10% >587 1020 Moist 10-40% 111-587 229 Mid 40-60% 50-111 71 Dry 60-90% 11-50 26 Low 90-100% <11 7

Allocations in the duration curve approach for each impaired stream reach are developed for the full range of flows experienced during the year. By adjusting the wasteload allocation, load allocation, and margin of safety to a range of five discrete flow intervals at each reach, a closer correspondence is obtained between the (flow- specific) loading capacity and the TMDL components (WLA + LA + MOS + RC), at the range of flow conditions experienced historically at each site.

Table 5.02 shows the conversion of the TSS surrogate value at a variable flows to a quantity of tons of TSS per day. This Report states flow in CFS, concentrations in mg/L and daily loading values in tons of TSS per day.

Table 5.02: Conversion Equations Flow: cubic feet/second (CFS) Concentration: milligrams/liter (mg/L) Total TSS per day in milligrams cfs x TSS in mg/L x 28.31 L/ ft3 x 86,400 seconds/day = mg/day Total TSS per day in tons TSS in mg/day / 907,184,740 mg/ton = Tons TSS/day

Example: Solve total TSS per day for the Mid Flow Value from table 5.01 Values: 71 CFS, TSS 70 mg/L 71 x 70 x 28.31 x 86,400 / 907,184,740 = 13.4 tons TSS/day

5.2 Components of TMDL Allocations

Each impaired reach in this Report is associated with a stream reach within the entire watershed and were listed to the 303(d) list based on sampling data or the MPCA led professional judgment group. When allocating the total loading capacity in the Redwood River watershed, the sum of all reaches to contributing to the reach that was listed as impaired would be included as part of the summation of that impaired reaches loading capacity. For instance, to determine the loading capacity the site RR1, the entire area of the watershed above that point is considered in the total loading capacity. This would mean that the components (WLA, LA, MOS, and RC) for the impaired reaches associated with RWR-53 and TC4A would also be included in the impaired reach associated with RR1, yet components of RWR-53 and TC4A are independent of each other in their own right. Furthermore, the impaired reaches of RWR-53 and TC4A

41 Redwood River Turbidity TMDL Report would also be part of the components of the load capacities in the reaches associated with sites RR1, and RWR-1 but would not be included in the reach at CC3 (see sites and how they relate to each other in Figure 3.01).

For each impaired reach and flow condition, the total loading capacity (TMDL) was divided into its component wasteload allocation, load allocation, reserve capacity, and margin of safety. The process was as follows:

5.2A Wasteload Allocation

Wastewater Treatment Facilities (WWTF) • Continuous discharge (mechanical) WWTF allocations were calculated using the average monthly effluent limit TSS concentrations and the permitted discharge design flow rates (average wet weather design flow). The effluent limits for most continuously directly discharging facilities is 30 mg/L. Consequently, the WWTF design flows for both of the mainstem sites exceed the stream flow at the low flow zone. Of course, actual WWTF flow can never exceed stream flow as it is a component of stream flow. • Non–continuous (stabilization ponds) discharges WWTF have an effluent limit of 45 mg/L. Allocations were calculated by assuming a six inches per day maximum discharge rate. Pond limit in kg/day x 1.2 estimate the load from the first six inches. This would be equivalent to the maximum volume discharged with a full pond. • The allocations in this TMDL project are by category. Effluent concentrations do not exceed the turbidity surrogate, which is 70 mg/L. Therefore, because wastewater effluent limits are below the turbidity surrogate, they are deemed not to cause or contribute to the violation of turbidity standards. Any future new or expanded discharges would be permissible provided that the limits are below the surrogate value. All dischargers in specific categories (ponds, mechanical facilities, water treatment plants, etc.) are subject to categorical allocations but these do not amount to loading caps applicable to individual permits.

Straight-Pipe Septic Systems Straight-pipe septic systems are illegal and un-permitted, and as such are assigned a zero wasteload allocation.

Stormwater NPDES Permits Stormwater regulated under a NPDES permit must be included in the Wasteload Allocation. This includes discharges associated with regulated Municipal Separate Strom Sewer Systems (MS4), industrial stormwater activities and construction stormwater activities.

The Wasteload Allocation (WLA) for mid-flow conditions loads was calculated by multiplying the export coefficient by the regulated MS4 area. The area

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represents the total developed area within regulated MS4 boundaries. The National Land Cover Data (NLCD) from 2001 was used to estimate the areas. More information regarding this data is under the section covering Land Use. The WLAs were calculated for mid-flow conditions and increased or decreased in proportion to flow for the other flow zones.

Livestock Facilities Requiring NPDES Permits Livestock facilities that have been issued NPDES permits are assigned a zero wasteload allocation. This is consistent with the conditions of the permit, which allow no pollutant discharge from the livestock housing facilities and associated sites. Discharge of sediment from fields may occur at times. Such discharges are covered under the load allocation portion of the TMDLs.

5.2B Load Allocations

Once the WLA and MOS were determined for a given reach and flow zone, the remaining loading capacity was considered load allocation. The load allocation includes nonpoint pollution sources that are not subject to permit requirements, as well as natural background sources of sediment from upland areas and near channel sources.

There may be concerns about not specifying natural background sources of sediment in the report. Natural background sources are not separately calculated because the research is not sufficient to define or allocate the sources. The EPA does not require this in a TMDL Report. The implementation process will define, in more detail, how these different sources will be addressed to achieve the Load Allocation.

Minnesota Rules Chapter 7050 establishes water quality standards for protection of Waters of the State, as delegated to the Minnesota Pollution Control Agency. Rules Chapter 7050 applies to all waters of the state, both surface and underground. This chapter creates a classification system of beneficial uses applicable to waters of the state, narrative and numeric water quality standards that protect specific beneficial uses, nondegradation provisions, and other provisions to protect the physical, chemical, and biological integrity of waters of the state.

Two areas of concern regarding the Load Allocation portion of the TMDL are natural background and natural causes. These concepts are defined in Minnesota Statues and Rules and those definitions are presented below.

Minnesota Rules Chapter 7050, Waters of the State defines natural causes as: “Natural causes” means the multiplicity of factors that determine the physical, chemical, or biological conditions that would exist in a water body in the absence of measurable impacts from human activity or influence.

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Minnesota Statute Chapter 114D.15, subdivision 10 defines natural background as: “Natural background” means characteristics of the water body resulting from the multiplicity of factors in nature, including climate and ecosystem dynamics, that affect the physical, chemical, or biological conditions in a water body, but does not include measurable and distinguishable pollution that is attributable to human activity or influence.

One of the reasons for improving our understanding of natural background in water quality improvement projects is that it can help determine the outer boundaries of what is reasonably achievable. Over time, to the extent that natural background can be more clearly defined through emerging research, our ability to set goals will also improve.

5.2C Margin of Safety

• An explicit 10 percent Margin of Safety was used in this TMDL project, thereby reducing the surrogates to 90 percent of their values.

5.2D Reserve Capacity

Reserve capacity is a portion of total allocation that shall accommodate future growth. A reserve capacity in this watershed was considered, but in light of the decrease in population and relative stability in percentage of land used for row cropping, it was decided that the LA would not be held to reserve capacity.

The overall population growth in the past decade for the Redwood River watershed averaged a loss of just over 5 percent. Changes in the human population should not change the load allocations provided in this Report.

Straight Pipe Septic Systems The number of straight pipe septic systems will decrease over time, as a result of the implementation of state and local rules, ordinances, and programs. Because these systems constitute illegal discharges, they are not provided a wasteload allocation for the impaired reaches in this Report. As such, other elements of the TMDL allocation will not change as these systems are eliminated.

Wastewater Treatment Facilities Flows at some wastewater treatment facilities are not likely to change greatly over time with negligible changes in the populations they serve. As long as current effluent discharge limits are met at these facilities, which are below the turbidity surrogate value, any new or expanded discharges would be permissible provided that the limits remain below the surrogates.

Municipal Separate Storm Sewer Systems

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Expansion of the current MS4 community in the watershed is not likely to take place, because of the declining population trend in the counties.

For the above reasons, no explicit adjustments were made to the wasteload or load allocations to account for human or livestock population growth. The MPCA will monitor population growth, urban expansion, and changes in agriculture, and reopen the TMDLs covered in this report if and when adjustments to allocations may be required.

Table 5.03 presents the resulting TMDL (WLA+LA) and MOS for the Redwood River impaired reach based on the five flow regimes. The values expressed are in tons TSS per day.

Table 5.03: TMDL and MOS for the Redwood River at USGS Station #05316500 near Redwood Falls Flow Condition TMDL* MOS* Allocation* High 174.48 19.39 193.9 Moist 38.95 4.33 43.3 Mid 12.18 1.35 13.5 Dry 4.06 0.45 4.5 Low 0.81 0.09 0.9 *Values expressed tons of TSS per day

Several of the turbidity impaired reaches did not have sufficient flow monitoring data. Flow data for the sites was estimated by normalizing data from the U.S. Geological Survey gage station. For example, the Threemile Creek impaired reach drainage area is 19.17 percent of the drainage area monitored by the Redwood Falls USGS gaging station. To determine flow zones for the Threemile Creek site, mean monthly flows were assumed to be 19.17 percent of the flow volumes at the Redwood Falls gauging station. This approach represents a valid method of determining flow values for ungaged areas of the watershed. This approach represents a valid method of determining flow values for unmonitored areas of the Basin.

Table 5.04: Redwood River Watershed Impaired Reaches Descriptions and Watershed Areas – Percentage of STORET # Area of sub- Watershed Percentage of Year River Assessment Used for watershed Area/Area at Area of Redwood Reach Description listed Unit ID Assessment (sq. miles) USGS Site River Watershed

Redwood Clear Cr to River Redwood Lk 02 07020006-509 S001-679 636.0 100.0% 90.2% Redwood Threemile Cr to River Clear Cr 10 07020006-503 S004-299 520.1 81.8% 73.8% T111 R42W S33 Redwood west line to River Threemile Cr 02 07020006-502 N/A 308.4 48.5% 43.7% Three Mile Headwaters to Creek Redwood R 04 07020006-504 S002-313 121.9 19.2% 17.3% # Uses the USGS site above Lake Redwood near Redwood Falls (Site #05316500)

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5.3 TMDL Allocations for Individual Impaired Reaches

In Sections 5.3.1 through 5.3.4 below, TMDL allocations are provided for the individual impaired reaches. Please note the following explanations and clarifications for portions of presented information in these sections:

• Tables showing permitted wastewater treatment facilities, industrial or municipal facilities with NPDES permits, and MS4 communities that are unique to the sub- watershed described in the section. These values along with any values upstream of the sub-watershed to calculate waste load allocations for the impaired reach of the sub-watershed.

• Calculations for the TMDL, (WLA, LA, and MOS) consider the total drainage area represented by the end of each listed reach. As such, listed reaches lower in the watershed will have allocations for the same sources covered in listed reaches upstream. In terms of actual load contributions, some upstream sources may not be as significant as those sources within or close to the downstream listed reaches due to the potential for sediment deposition in the floodplain as waters travel downstream in the watershed.

• Tables showing the TSS loading capacities and allocations are provided and illustrate the TMDL, (WLA, LA and MOS) for each of five flow zones. (Due to rounding the (WLA, LA, and MOS) may not exactly add up to the loading capacities for some flow zones.)

• There may be multiple NPDES sites within a watershed that either do not discharge enough to be assigned a WLA or are temporary in nature and not considered to be a long-term contributor to the WLA of this TMDL. Information regarding these permit holders is available from the Minnesota Pollution Control Agency “Delta” water quality database.

• The resulting reduction percentage is only intended as a rough approximation. Reductions are calculated for five different flow regimes, and as such, encompass a large range of flow within each regime. This contributes uncertainty in the percent reduction calculations. Reduction percentages are not a required element of a TMDL (and do not supersede the allocations provided), but are included here to provide a starting point to assess the magnitude of the effort needed in the watershed to achieve the standard.

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5.3.1 Redwood River; Clear Creek to Redwood Lake (AUID: 07020006-509)

The Redwood River reach from Clear Creek to Redwood Lake (Figure 5.3.1A) was added to the Section 303(d) Clean Water Act impaired waters list in 2002. The primary source of data that led to this listing was the Redwood River Watershed Project (RRWP) Phase I Redwood River Clean Water Partnership (CWP). The sampling site is RR1 (STORET# S001-679). The drainage area to the downstream end of this impaired reach is 636 square miles.

Figure 5.3.1A: Redwood River; Clear Creek to Redwood Lake

Land use in the reach of the impairment is 85.0 percent cultivated 5.3 percent grass, 3.7 percent forest, 1.1 percent water/wetlands, and 4.9 percent urban. This reach contains no communities served by a permitted wastewater treatment facility (Table 5.3.1A), and there is one community, Redwood Falls, that requires an MS4 permit (Table 5.3.1B). There are three municipal or industrial NPDES permitted facilities within this reach (Table 5.3.1C).

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Table 5.3.1D describes the average TSS loading capacities for this reach by flow zone, as well as the component wasteload allocations, load allocations, and margin of safety. Table 5.3.1E shows TSS loading reductions needed to achieve water quality standards, by flow zone. The loading capacities and reductions for five flow zones were developed using flow data from the USGS gage site station (USGS #05316500) on the Redwood River above Lake Redwood. The flow duration curve for this reach is in Appendix B.

Table 5.3.1A: Wastewater Treatment Facilities Name Permit Number Discharge (mg/L) WLA (TSS Tons/day) None

Table 5.3.1B: Permitted Municipal Separate Storm Sewer System (MS4) Communities Community Permit Population Category Number Estimate Redwood Falls MS400236 XXX Municipal

Table 5.3.1C: Industrial or Municipal NPDES Permits Facility ID Number Description Redwood Co. SWIS00083 Industrial Stormwater Permit – 0 WLA Sanitary Landfill Redwood Falls 116215906 Industrial Stormwater Permit – 0 WLA Ready Mix – S & S Brown-Wilbert Co, 083459966 Industrial Stormwater Permit – 0 WLA Redwood Falls

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Table 5.3.1D: Daily TSS Loading Capacities and Allocations – Redwood River, Clear Creek to Redwood Lake (AUID: 07020006-509)

Redwood River - Clear Creek to Lake Redwood Flow Zone High Moist Mid Dry Low Total Daily Loading Capacity 193.9 43.3 13.5 4.5 0.9 TSS - Tons/day Waste Load Allocation Permitted Wastewater Treatment Facilities 1.72 1.72 1.72 1.72 0.00* Communities Subject to MS4 NPDES Requirements 3.95 0.88 0.28 0.09 0.02 Industrial/Construction Stormwater (NPDES) 0.23 0.05 0.02 0.01 0.01 Waste Load Allocation Total 5.91 2.66 2.02 1.83 0.03 Margin of Safety 19.39 4.33 1.35 0.45 0.09 Load Allocation 168.57 36.29 10.15 2.23 0.78

*-WWTF Discharges are limited to specific timeframes (April1 through June 15 and September 15 through December 15) and are also permitted only to discharge below the water quality standards. Under low flow conditions, WWTP have been determined to not be a major source of loading.

Table 5.3.1E: Daily TSS Loading Reductions – Redwood River, Clear Creek to Redwood Lake (AUID: 07020006-509)

Redwood River - Clear Creek to Flow Zone Lake Redwood High Moist Mid Dry Low Total Loading Capacity* 193.9 43.3 13.5 4.5 0.9 90th Percentile Loading* 2116.9 259.8 17.6 6.1 N/A** Reduction in TSS* 1923.0 216.5 4.1 1.6 N/A** % Reduction 90.8% 83.3% 23.3% 26.2% 0.0% *All values in tons/day of TSS **Insufficient data to determine loading and reductions

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5.3.2 Redwood River; Threemile Creek to Clear Creek (AUID: 07020006-503)

The Redwood River reach from Theemile Creek to Clear Creek (Figure 5.3.2A) was added to the Section 303(d) Clean Water Act impaired waters list in 2010. The primary source of data that led to this listing was collected by the MCPA through their Citizen Stream Monitoring Program (CSMP) – STORET ID S004-299. The drainage area to the downstream end of this impaired reach is 520 square miles.

Figure 5.3.2A: Redwood River; Clear Creek to Redwood Lake

Land use in the reach of the impairment is 89.0 percent cultivated 3.5 percent grass, 2.6 percent forest, 0.8 percent water/wetlands, and 4.0 percent urban. This reach contains one community, Vesta, served by a permitted wastewater treatment facility (Table 5.3.2A), and there are no communities requiring MS4 permits (Table 5.3.2B). There is one industrial facility with a NPDES permit (Table 5.3.2C).

Table 5.3.2D describes the average TSS loading capacities for this reach by flow zone, as well as the component wasteload allocations, load allocations, and margin of safety. Table 5.3.2E shows TSS loading reductions needed to achieve water quality standards,

50 Redwood River Turbidity TMDL Report by flow zone. The loading capacities and reductions for five flow zones were developed using flow data from the USGS gage site station (USGS #05316500) on the Redwood River above Lake Redwood. The flow duration curve for this reach is in Appendix B.

Table 5.3.2A: Wastewater Treatment Facilities Name Permit Number Discharge (mg/L) WLA (TSS Tons/day) Vesta MNG580043 45 0.27

Table 5.3.2B: Permitted Municipal Separate Storm Sewer System (MS4) Communities Community Population Estimate Category none

Table 5.3.2C: Industrial or Construction NPDES Permits Facility ID Number Description Waste Management A00019940 Industrial Stormwater Permit – 0 WLA – Marshall Recycling

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Table 5.3.2D: Daily TSS Loading Capacities and Allocations – Redwood River; Threemile Creek to Clear Creek (AUID: 07020006-503)

Redwood River - Threemile Creek to Clear Creek Flow Zone High Moist Mid Dry Low Total Daily Loading Capacity 157.6 35.2 11.0 3.7 0.7 TSS - Tons/day Waste Load Allocation Permitted Wastewater Treatment Facilities 1.72 1.72 1.72 1.72 0.00* Communities Subject to MS4 NPDES 3.71 0.83 0.26 0.09 0.02 Requirements Industrial/Construction Stormwater 0.19 0.04 0.01 0.01 0.01 (NPDES) Waste Load Allocation Total 5.62 2.59 1.99 1.81 0.02 Margin of Safety 15.76 3.52 1.10 0.37 0.07 Load Allocation 136.22 29.08 7.90 1.49 0.64

Table 5.3.2E: Daily TSS Loading Reductions – Redwood River, Threemile Creek to Clear Creek (AUID: 07020006-503)

Redwood River - Threemile Creek to Flow Zone Clear Creek High Moist Mid Dry Low Total Loading Capacity* 157.6 35.2 11.0 3.7 0.7 90th Percentile Loading* N/A** N/A** N/A** N/A** N/A** Reduction in TSS* N/A** N/A** N/A** N/A** N/A** % Reduction 0.0% 0.0% 0.0% 0.0% 0.0% *all values in tons/day of TSS **Insufficient data to determine loading and reductions

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5.3.3 Redwood River, T111 R42W S33 west line (Lynd, MN) to Threemile Creek (AUID: 07020006-502)

Redwood River from near Lynd, MN to Threemile Creek was added to the Section 303(d) Clean Water Act impaired waters list in 2002. Turbidity impairment along this reach of the Redwood River was determined by the MPCA Professional Judgment Group. There were too few data points and standard violations to determine impairment strictly by sampling. Since impairment determination, in 2002, there has been an increase in water samples taken from this reach of the Redwood Rive. Those sampling sites are Marshall (STORET# S003-702) and RWR-53 (STORET# S001-199). The drainage area to the downstream end of this reach is 308.4 square miles.

Figure 5.3.3A: Redwood River; T111 R42W S33 west line (Lynd, MN) to Threemile Creek

Land use in this reach is approximately 76.3 percent cultivated, 11.4 percent grass, 6.1 percent urban, 3.2 percent water/wetlands, 2.9 percent forest. There are five wastewater treatment facilities in this reach (Table 5.3.3A). The community of Marshall

53 Redwood River Turbidity TMDL Report also requires a MS4 Stormwater permit (Table 5.3.3B). The MS4 permit covers approximately 12.18 square miles, or 3.95 percent of the entire watershed to this point, and allows for growth. There are four municipal or Industrial facilities issued NPDES permits (Table 5.3.3C).

Table 5.3.3D describes the average TSS loading capacities for this reach by flow zone, as well as the component wasteload allocations, load allocations, and margin of safety. Table 5.3.3E shows TSS loading reductions needed to achieve water quality standards, by flow zone. The loading capacities and reductions for five flow zones were developed using flow data from the USGS gage site station (USGS #05316500) on the Redwood River above Lake Redwood. The flow duration curve for this reach is in Appendix B.

Table 5.3.3A: Wastewater Treatment Facilities Name Permit Number Discharge (mg/L) WLA (Tons-TSS/day) Marshall MN0022179 30 0.56 Ruthton MNG580105 45 0.07 Tyler MNG580116 45 0.20 Russell MNG580062 45 0.11 Lynd MNG580030 45 0.06

Table 5.3.3B: Permitted Municipal Separate Storm Sewer System (MS4) Communities Community Permit Number Population Category Estimate Marshall #MS400241 12,735 Designated by rule: Over 10,000 people. 3.95% of the area of the watershed

Table 5.3.3C: Industrial or Construction NPDES Permits Facility ID Number Description Magellan Pipeline Co LP - Marshall MN0059838 Industrial Permit, 5 mg/L Discharge Limit – 0 WLA ADM Corn Processing – Marshall MN0057037 Industrial Permit, 30 mg/L Discharge Limit – 0.60 WLA D & G Excavating Inc. MNG490067 Industrial Permit – 0 WLA McLaughlin & Schulz Inc. MNG490019 Industrial Permit – 0 WLA

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Table 5.3.3D: Daily TSS Loading Capacities and Allocations – Redwood River, T111 R42W S33 west line (Lynd, MN) to Threemile Creek (AUID: 07020006-502)

Redwood River - T111 R42W S33, westline to Threemile Creek Flow Zone High Moist Mid Dry Low Total Daily Loading Capacity 94.0 21.0 6.6 2.2 0.4 TSS - Tons/day Waste Load Allocation Permitted Wastewater Treatment Facilities 1.61 1.61 1.61 1.61 0.00* Communities Subject to MS4 NPDES 3.71 0.83 0.26 0.09 0.02 Requirements Industrail/Construction Stormwater 0.11 0.03 0.01 0.00 0.00 (NPDES) Waste Load Allocation Total 5.44 2.47 1.88 1.70 0.02 Margin of Safety 9.40 2.10 0.66 0.22 0.04 Load Allocation 79.20 16.43 4.02 0.26 0.37

Table 5.3.3E: Daily TSS Loading Reductions – Redwood River, T111 R42W S33 west line (Lynd, MN) to Threemile Creek (AUID: 07020006-502)

Redwood River - T111 R42W S33, Flow Zone westline to Threemile Creek High Moist Mid Dry Low Total Loading Capacity* 94.0 21.0 6.6 2.2 0.4 90th Percentile Loading* N/A** N/A** N/A** N/A** N/A** Reduction in TSS* N/A** N/A** N/A** N/A** N/A** % Reduction 0.0% 0.0% 0.0% 0.0% 0.0% *all values in tons/day of TSS **Insufficient data to determine loading and reductions

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5.3.4 Threemile Creek, Headwaters to Redwood River (AUID: 07020006-504)

Threemile Creek, Headwaters to Redwood River (Figure 5.3.4A) was added to the Section 303(d) Clean Water Act impaired waters list in 2006. The primary source of data that led to this listing was the RRWP Phase I CWP. The sampling site is TC4A (STORET# S002-313). The drainage area to the downstream end of this reach is 121.9 square miles.

Figure 5.3.4A: Threemile Creek; Headwaters to Redwood River

Land use in this reach is approximately 84.0 percent cultivated, 8.5 percent grass, 1.9 percent forest, 1.6 percent water/wetlands and 4.0 percent urban. The drainage area contains the city of Ghent which served by a permitted wastewater treatment facilities (Table 5.3.4A), and there are no communities requiring MS4 permits (Table 5.3.4B). There are no industrial facilities issued NPDES permits (Table 5.3.4C).

Table 5.3.4D describes the average TSS loading capacities for this reach by flow zone, as well as the component wasteload allocations, load allocations, and margin of safety. Table 5.3.4E shows TSS loading reductions needed to achieve water quality standards,

56 Redwood River Turbidity TMDL Report by flow zone. The loading capacities and reductions for five flow zones were developed using flow data from the USGS gage site station (USGS #05316500) on the Redwood River above Lake Redwood. The flow duration curve for this reach is in Appendix B.

Table 5.3.4A: Wastewater Treatment Facilities Name Permit Number Discharge (mg/L) WLA (TSS-Tons/day) Ghent MNG580121 45 0.06

Table 5.3.4B: Permitted Municipal Separate Storm Sewer System (MS4) Communities Community Population Estimate Category None

Table 5.3.4C: Industrial or Construction NPDES Permits Facility ID Number Description None

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Table 5.3.4D: Daily TSS Loading Capacities and Allocations – Threemile Creek, Headwaters to Redwood River (AUID: 07020006-504)

Threemile Creek – Headwaters to Redwood River Flow Zone High Moist Mid Dry Low Total Daily Loading Capacity 37.2 8.3 2.6 0.9 0.2 TSS - Tons/day Waste Load Allocation Permitted Wastewater Treatment Facilities 0.06 0.06 0.06 0.06 0.00* Communities Subject to MS4 NPDES 0.00 0.00 0.00 0.00 0.00 Requirements Industrail/Construction Stormwater 0.04 0.01 0.00 0.00 0.00 (NPDES) Waste Load Allocation Total 0.10 0.07 0.06 0.06 0.00 Margin of Safety 3.72 0.83 0.26 0.09 0.02 Load Allocation 33.36 7.40 2.28 0.72 0.15

Table 5.3.4E: Daily TSS Loading Reductions – Threemile Creek, Headwaters to Redwood River (AUID: 07020006-504)

Threemile Creek – Headwaters to Flow Zone Redwood River High Moist Mid Dry Low Total Loading Capacity* 37.2 8.3 2.6 0.9 0.2 90th Percentile Loading* 369.9 31.1 14.8 1.4 N/A** Reduction in TSS* 332.7 22.8 12.2 0.5 N/A** % Reduction 89.9% 73.3% 82.4% 35.7% 0.0% *all values in tons/day of TSS **Insufficient data to determine loading and reductions

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6.0 Margin of Safety

Under Section 303(d) of the Clean Water Act, a MOS is required as part of a TMDL report. The purpose of the MOS is to account for uncertainty that the allocations will result in attainment of water quality standards. For the four impaired reaches covered in this Report, an explicit margin of safety of ten percent is provided for each of the flow periods for each impaired reach. As described in Section 5 and Appendix A of this document, the MOS is calculated to be ten percent of the maximum loading capacity. The MOS ensures that allocations will not exceed the load associated with the minimum flow in each zone. Because the allocations are a direct function of daily flow, accounting for potential flow variability is the appropriate way to address the MOS. The minimum daily flows over long periods of record define the MOS for the low flow zone.

7.0 Seasonal Variation

The flow duration approach utilized in this Report captures the full range of flow conditions throughout the year. Seasonal variation in flow is a key part of TMDL development. Daily loads are directly proportional to flows.

Turbidity levels are generally at their worst following significant storm events during the spring and early summer months. Seasonal variations are somewhat more difficult to generalize given reach-specific differences. Regardless, such conditions and variation are fully captured in the duration curve methodology used in this TMDL.

The EPA requires that TMDLs take into account “critical conditions for stream flow, loading, and water quality parameters.” This requirement is fulfilled through the analysis and discussion of seasonality, and effects of weather and streamflow, contained in Sections 2.6, 3.7, and Appendix A of this Report. While there is some variability among the impaired reaches addressed in this Report, critical conditions include storm events, and spring (April-June).

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8.0 Monitoring Plan

The goal of the monitoring plan is to assess if the reduction strategies are effective in attaining water quality standards and designated uses.

RCRCA plans to continue their annual condition monitoring efforts in the Redwood River Watershed. In an effort to maintain a contiguous monitoring database, the subsequent implementation plan will include a monitoring plan and quality assurance project plan. Further effectiveness monitoring sites may be added upon recommendations from the stakeholder technical advisory committee. Implementation activities supported by an approved implementation plan will be evaluated every five years and modified as needed. Annual results will be included in the yearly Redwood River Watershed Monitoring Summary.

The majority of turbidity and TSS sampling data collected over the past fifteen years is attributed to the Redwood River Clean Water Partnership (CWP) project in the basin. The diagnostic and implementation phases of this CWP are complete and provided funding for this watershed through 2009. RCRCA is maintaining the contiguous monitoring through the use of CWA 319 and general fund dollars for 2011. Monitoring after 2012 will depend on the approval of this TMDL and implementation plan to maintain the sampling data base and evaluate effectiveness.

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9.0 Implementation Strategy

9.1 Implementation through Source Reduction Strategies

This section provides an overview of implementation options and considerations to primarily address nonpoint sources of turbidity for this TMDL. RCRCA has proposed a watershed-wide approach to achieving water quality standards for turbidity within ten years. Methods in the implementation plan set forth in the original Redwood River diagnostic study, a plan which has been in place since 1993, will be used as a template for the implementation plan for this TMDL project. The final implementation plan will be developed within a year of the final approval of the Report by the EPA. The implementation plan developed by the stakeholder advisory committee will spell out what type of best management practice (BMP) to use and where they will be applied in the sub-watersheds of the impaired reaches and will project the cost and funding sources for their application.

Table 9.01 below brings the main potential sources (surface water connectivity facilitation, streambank and bed erosion, National Pollutant Discharge Elimination System (NPDES) permit holders, septic systems, near-stream pastures, overland runoff, impervious surfaces, unpaved roads, aggregate mining, stormwater and construction activities) into the analysis. In this table, these sources are portrayed in terms of “implementation opportunities” and are associated with the likely flow zones in which they would be effective. Using this table, in conjunction with the load duration curve, local stakeholder knowledge and other information, a project team can start to rule in or out some sources and potentially rank them from most significant to least significant as well as point towards some implementation strategies.

Table 9.01: Implementation Opportunities for the Different Flows Regimes Duration Curve Zone Flood Moist Mid Dry Drought Mining and Construction WWTF (nutrients) Water Retention/Flood Control SSTS (nutrients) Implementation Overland Runoff Controls Pasture management Opportunities Urban stormwater management Crop Residue Management Nutrient Management Manure management (nutrients) Adapted from Revised SE Regional Fecal Coliform TMDL, Appendix A.

Appendix C includes load duration curves for each sub-watershed in an attempt to target areas for reducing TSS.

RCRCA received grants in 2002, 2004, 2006, and 2010 to implement best management practices for improving water quality. The BMPs include: CRP buffers, alternative tile intakes, grassed waterways, livestock exclusion, sediment basins, nutrient management

61 Redwood River Turbidity TMDL Report plans, wetland restorations, and streambank stabilization. These activities are designed to reduce sediment movement and attendant nutrients by reducing availability of direct conveyance of material to surface water and holding water on the landscape. The result of erosion reduction projects work toward turbidity reduction among other pollutant reductions. Some of these activities are listed below.

• Pasture Management/Livestock Exclusion Plans – Many pastured animals use nearby surface waters for drinking water when they are pastured. Unfortunately, the activity in or near surface waters can destabilize banks and allow nutrients from manure to enter into surface waters. Livestock exclusion, by fencing off areas where livestock activity exists and replacing the surface water sources with an alternate watering system will exclude livestock from waters and with proper buffering, can reduce the conveyance of nutrients associated with runoff and turbidity associated with sediment from destabilized and denuded streambanks. Another way to ensure better coverage in pastures and pasture health is through rotational grazing. Rotational grazing is a method of grazing where pastures are divided into sections with the goal of allowing pasture grass time to grow back after being grazed. Other pasture activities to ensure that pastures aren’t overgrazed include proper grazing timing and grazing the proper amount of animals per acre.

• Manure/Nutrient Management Plans – State rules dictate that feedlots larger than 300 animal units are required to develop manure management plans. Manure management plans serve to account for the storage and application of manure to ensure that there is enough land to accommodate the amount of manure produced by a livestock operation. Manure management is one of the integral parts of a nutrient management plan. Both serve to plan nutrient/manure application according to the need of the land. Rates of application consider the crop, soil type, previous crops, history of fertilizer/manure application and incorporation/application methods. Proper application rates, placement, and timing of fertilizer and manure application can reduce the movement and availability of bacteria and nutrients to surface water sources which can lead to turbidity through algae growth.

• Overland Runoff Controls – Runoff from a variety of landscapes can be buffered from surface water using adequate vegetation. Vegetative practices minimize nutrient, bacteria, and sediment runoff through increased infiltration and decreased pollutant transport. Wetland Restorations, Filter Strips and Grassed Buffers, and Grassed Waterways are designed to allow water to flow without channelizing and filter out pollutants from overland runoff. Although not a grass based practice, conservation tillage will also provide benefits that will ultimately reduce turbidity. Clean water can also be diverted away from feedlots so as not to pick up pollutants including manure, nutrients, and sediment which may be incorporated in surface water systems. • Water Retention Projects/Flood Controls – Terrain of steeper grades can create gullies in areas devoid of vegetation or actually become channelized with high

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precipitation events. Structures such as terraces, water and sediment control basins, and grade stabilization structures are designed to pool higher flow events on the land and meter out flow to surface waters in an effort to dissipate erosion causing energy associated with high precipitation events. These techniques are designed to keep sediment and attendant pollutants in place on the land while dampering energy due to large influxes of water from entering streams during storm events which can contribute to bank erosion.

• Direct Sediment/Nutrient Contribution Controls – Some situations such as open tile intakes, stream bank sloughing, and near channel gullies allow direct contribution of turbidity causing pollutants and sediment to surface waters. Practices to replace open tile intakes with filtered or blind intakes and structural practices to control near stream gullies, stream bank and shore land erosion are designed to keep sediments from surface waters.

• Mining and Construction Activities – Construction and mining activities are required to have permits to operate and discharge to surface waters. Counties, Regional Development Commissions, and MPCA staff will work with these parties to ensure continued compliance as part of their permits.

• Urban Stormwater Management – Counties, Regional Development Commissions and MPCA staff will work with city officials to ensure continued compliance as part of their permits.

• Waste Water Treatment Facilities – Counties, Regional Development Commissions and MPCA staff will work with WWTFs to ensure continued compliance as part of their permits.

• Subsurface Septic Treatment Systems – Three percent low interest loan dollars are available to aid landowners in upgrading their SSTS. An approximate number of SSTS needs can be inferred from the estimation of non-compliant septic systems. We can also include SSTS needs in unsewered communities by household. With a cost estimated at about $8,000, the roughly 1,000 failing systems combined with systems that would account for unsewered communities, would cost on the order of $8,000,000 to replace failing systems in the Redwood river watershed.

9.2 Locally Targeted Implementation

The four impaired reaches can be used as priority areas in the implementation plan. Smaller watershed area will ensure targeted BMP implementation. RCRCAs goal is to help make these changes happen through education, training, and monetary incentives. Below are implementation plan ideas by subwatershed. Most of the proposed practices relate to agricultural BMPs, but SSTS and unsewered communities will also be addressed.

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• The Lower Redwood Watershed (RR1, STORET# S001-679): The Redwood River from Clear Creek to Redwood Lake (Assessment reach ID #07020006- 509) was identified a priority area in the watershed in 2002 for turbidity impairments. The Redwood River from Threemile Creek to Clear Creek (Assessment reach ID #07020006-503) was identified a priority area in the watershed in 2010 for turbidity impairments based on an MPCA assessment. As this subshed is a section of the Redwood River, it reflects tributaries to the lower end of this section as well as areas immediate to the subshed itself. Based on sampling and the load duration curve, this subshed tends to exceed the turbidity standards during “high”, “moist” and “mid-range” flow conditions. Implementation of projects such as manure and nutrient management plans, practices for water volume reduction, and pasture management regiments are a few actions that should help to realize the improvement needed to achieve reduction goals.

• The Middle Redwood Watershed (RWR-53, STORET# S001-199 and Marshall, STORET# S003-702): The Redwood River from the west line of T111 R42w S33 to Three Mile Creek (Assessment reach ID #07020006-502) was identified a priority area in the watershed in 2002 for turbidity. As this subshed is a section of the Redwood River, it reflects tributaries to the lower end of this section as well as areas immediate to the subshed itself. Based on sampling and the load duration curve, this subshed tends to exceed the turbidity standard during the “high” conditions. However, sampling at the USGS site south of Marshall suggests that the site generally was compliant with the standards. So the focus of implementation in this subshed would seem to be of better use in the portion of the subshed below the Marshall site. Implementation of projects such as observance of storm water procedures, structural methods to slow water volume, manure management plans, urban runoff controls and pasture management regiments would be prudent for the higher flows. These are a few actions that should help to realize the improvement needed to achieve reduction goals.

• Three Mile Creek (TC4A, STORET# S002-313): Three Mile Creek from its headwaters to the Redwood River (Assessment reach ID #07020006-504) was identified a priority area in the watershed in 2004 for turbidity impairments. The Three Mile Creek subshed reflects the whole of the subshed itself. Based on sampling and the load duration curve, this subshed tends to exceed standards for turbidity during all flow conditions but is most problematic during the “high”, “moist”, and “average” flow conditions. Implementation of projects such as such as observance of storm water procedures, structural methods to slow water volume, manure management plans and pasture management regiments would be prudent for the higher flows. Municipal discharge management, animal exclusion, pasture management, and replacement of failing Subsurface Septic Treatment Systems would better serve the sub-shed during the dry periods. These are a few actions that should help to realize the improvement needed to achieve reduction goals.

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10.0 Reasonable Assurance

10.1 Evidence of BMP Implementability

The source reduction strategies listed are shown to be successful in reducing sediment and nutrient transport and to be capable of widespread adoption by land owners and local resource managers. Many of the BMPs listed in section 9.1 are part of the original Redwood River Clean Water Project’s implementation plan. RCRCA will apply for available grants and loans to continue implementation of these BMPs. RCRCA has a proven history backed with an extensive database, a long-term monitoring program, and an organizational structure that remains supportive and flexible to ensure that projects such as the Redwood River Clean Water Project and the Cottonwood River Restoration Project are successful. This success can be viewed in the 2001 Final Report, “Evolution of Watershed Restoration”, which can also be found at our website. Continued best management projects concentrated in priority areas of the watershed have helped the Redwood River Watershed realize a reduction and stabilization in sediment and nutrient loads. In the same way, acheivements in turbidity reductions will be effective if the methods and efforts listed in sectio 9.1 are tailored to priority areas but more importantly, in such a way that will be effective at priority times of the year in these areas.

10.2 Non-regulatory, Regulatory, and Incentive-Based Approaches

The lead for implementation will be sponsored by the Redwood-Cottonwood Rivers Control Area. The local work group of the RCRCA is composed of RCRCA technical staff, county representatives and personnel from Soil and Water Conservation Districts, Board of Soil and Water Resources, Department of Natural Resources, Minnesota Pollution Control Agency, and the Natural Resources and Conservation Services. The local work group will monitor and evaluate the implementation strategies, and will advise and make recommendations on the progress of the strategies to RCRCA.

11.0 Public Participation

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12.0 References American Veterinary Medical Association (AVMA). 2007. http://www.avma.org/press/releases/071211_sourcebook.asp “AVMA Releases Latest Stats on Pet Ownership and Practices”

Baxter-Potter, W., and M. Gilliland.1988. Bacterial pollution in runoff form agricultural lands. J. Environmental Quality. 17(1):27-34

Cleland, B, R. 2002. TMDL development from the “bottom up” – part II: using duration curves to connect the pieces. National TMDL Science and Policy 2002 -- WEF Specialty Conference. Phoenix, AZ

Daberkow, Kelli. 2007. Minnesota Pollution Control Agency. Personal communication

Davis, R.K., S. Hamilton, and J.V. Brahana. 2005. Escherichia Coli Survival in Mantled Karst Springs and Streams, Northwest Arkansas Ozarks, USA

Ganske, Lee. 2007. Minnesota Pollution Control Agency. Personal communication

Gillingham, Brad. 2008. Minnesota Pollution Control Agency. Personal communication

Howey, Steve. 2007. Minnesota Pollution Control Agency. Personal communication

Jolley, L.W., J.W. Pike, M. Goddard. 2004 The Role of Bottom Sediments in the Storage and Transport of Indicator Bacteria. Department of Forestry and Natural Resources, Clemson University. Poster Presentation.

League of Minnesota Cities. 2003. Directory of Minnesota city officials. League of MN Cities. 296 p.

Meyer, Pam. 2006. Minnesota Pollution Control Agency. Personal communication

Minnesota Department of Natural Resources (MnDNR). 2003. Personal communication.

Minnesota Environmental Quality Board (EQB). 1999. Generic Environmental Impact Statement on Animal Agriculture. EQB, St. Paul MN.

Minnesota Pollution Control Agency. 2006. Revised regional total maximum daily load evaluation of fecal coliform bacteria impairments in the lower Mississippi river basin in Minnesota. MPCA, St. Paul. 123p

Mulla, D. J., A. S. Birr, G. Randall, J. Moncrief, M. Schmitt, A. Sekely, and E. Kerre, 2001, Technical work paper, Impacts of Animal Agriculture on Water Quality. EQP and Citizen Advisory Comm., 125 p.

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Redwood-Cottonwood Rivers Control Area (RCRCA). 1993. Redwood River Clean Water Project Final Report

Redwood-Cottonwood Rivers Control Area (RCRCA). 1999. Redwood River Clean Water Project Three Year Work Plan 1998-2000.

Runholt, Muriel. 2007. Minnesota Pollution Control Agency. Personal communication

US Census Bureau, http://www.census.gov/popest/cities/tables/SUB-EST2006-04- 27.xls, “Table 4: Annual Estimates of the Population for Incorporated Places in Minnesota, Listed Alphabetically: April 1, 2000 to July 1, 2006”

USEPA. 2001. Protocol for Developing Pathogen TMDLs, 1st Edition. EPA 841-R-00- 002. Office of Water, USEPA, Washington, DC. 132 pp.

Water Resources Center, Minnesota State University, Mankato & Sibley County. 2006. Fecal Coliform TMDL Assessment for High Island Creek and Rush River.

Wieskel, P.K., B.L. Howes, and G.R. Heufelder. 1996. Coliform contamination of a coastal embayment: sources and transport pathways. Environmental Science Technology 30(6): 1872-1881.

Yagow, G. and V Shanholtz. 1998. Targeting sources of fecal coliform in Mountain Run. An ASAE Meeting Presentation. 98-2031. July 12-26, 1998.

Zadak, Christopher. 2007. Minnesota Pollution Control Agency. Personal communication

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Appendix A: Redwood River Turbidity TMDL: Methodology for TMDL Equations and Load Duration Curves

The loading capacity determination used for this report is based on the process outlined in the MPCA report, “Turbidity TMDL Protocols and Submittal Requirements” (March 2007). This process is known as the “Duration Curve” method.

The turbidity value cannot be directly related to flow for determination of loading, therefore the TSS surrogate value is used to determine loading. Loading capacities for TSS are related directly to flow volume. As flows increase, the loading capacity of the stream will also increase. Thus, it is necessary to determine loading capacities for a variety of flow zones.

For this approach, daily flow values for each site are sorted by flow volume, from highest to lowest and a percentile scale is then created (where a flow at the Xth percentile means X percent of all measured flows equal or exceed that flow). Five flow zones are used in this approach: “high” (0-10th percentile), “moist” (10th- 40th percentile), “mid-range” (40th-60th percentile), “dry” (60th-90th percentile) and “low” (90th-100th percentile). The flows at the mid-points of each of these zones (i.e., 5th, 25th, 50th, 75th and 95th percentiles) are multiplied by the fecal coliform standard (200 org/100 mL) except for Class 7 waters which is 1,000 org/100 mL. A conversion factor reports the allowable maximum loads in units of billions of organisms per day. For example, if the “mid-range” (50th percentile) flow is 100 cubic feet per second (cfs), the loading capacity or TMDL would be:

100 cfs x 70 mg/1L x 28.31 L/cubic ft x 86,400 sec/day ÷ 907,184,740 mg/ton = 18.87 tons of TSS per day

The flow monitoring data used in this project was from two U.S. Geological Survey gage stations. Thirty years of flow data from the USGS stations were used for the Redwood River calculations (1977-2006).

Flow data for the sites was estimated by normalizing data from the two U.S. Geological Survey gage stations. For example, the Clear Creek impaired reach drainage area is 13.1 percent (83.4/636) of the drainage area monitored by the RR1 USGS gaging station. Calculated flows were then checked against 12 years of available flow data for the small stream which showed a reasonable degree of alignment.

It was decided to use USGS data for all sites in the Redwood River watershed to better reflect the range of hydrologic conditions in the watershed by having a wider variety of conditions to use for the Duration Curve.

TMDLs were calculated for all the flow zones for each listed reach of the project. The TMDLs were then divided into a Margin of Safety (MOS), Wasteload Allocations (WLAs), Load Allocation (LA), and Reserve Capacity (RC).

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The MOS accounts for uncertainty in the TMDL allocation process. The MOS was given an explicit ten percent value of the total TMDL. The resulting value was converted to a load and used as the MOS. The final available load and wasteload allocation is the TMDL minus the MOS.

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Appendix B: Sample Data for Table 3.02

Site: RR1 – 07020006-509 – (S001-679)

07020006-509 RCRCA Grab Sampling Data RR1 S001-679 2003 2004 2005 Date: Turbidity Date: Turbidity Date: Turbidity 7/31/2003 16 1/12/2004 10 1/19/2005 7 8/13/2003 25 3/24/2004 12 2/17/2005 6.8 9/29/2003 30 4/14/2004 11 3/22/2005 8 10/22/2003 17 5/5/2004 14 3/31/2005 26 11/13/2003 4 5/27/2004 130 4/13/2005 160 12/22/2003 8 6/3/2004 80 4/14/2005 100 6/12/2004 120 4/19/2005 37 6/30/2004 29 4/26/2005 18 8/23/2004 7 5/16/2005 23 9/15/2004 60 5/18/2005 120 9/29/2004 16 5/24/2005 25 10/25/2004 20 6/8/2005 24 11/16/2004 10 6/27/2005 31 12/9/2004 7 7/5/2005 18 7/19/2005 19 8/17/2005 22 9/13/2005 90 9/14/2005 110 9/16/2005 49.5* 9/27/2005 38 10/17/2005 18 11/21/2005 6 12/22/2005 9 * = Average of two or more samples

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07020006-509 RCRCA Grab Sampling Data RR1 S001-679 2006 2007 2008 Date: Turbidity Date: Turbidity Date: Turbidity 1/11/2006 7 1/26/2007 8 1/15/2008 8 2/14/2006 6 2/21/2007 9 2/13/2008 4 3/31/2006 170 3/13/2007 150 3/4/2008 4 4/4/2006 38 3/16/2007 86 4/8/2008 14 4/11/2006 37 3/19/2007 74 4/16/2008 17 4/25/2006 21 4/2/2007 100 4/18/2008 120 5/2/2006 36 4/4/2007 78 4/21/2008 74 5/15/2006 19 4/16/2007 50 4/28/2008 64 5/30/2006 16 4/20/2007 48 5/6/2008 50 6/12/2006 31 5/3/2007 31 5/21/2008 42 6/27/2006 44 5/8/2007 35 6/6/2008 59 7/10/2006 21 5/29/2007 15 6/9/2008 74 7/28/2006 35 6/4/2007 81 6/13/2008 97 8/2/2006 37 6/18/2007 33 6/26/2008 65 8/29/2006 66 7/5/2007 18 7/8/2008 27 9/12/2006 48 7/26/2007 51 7/31/2008 8 9/26/2006 50 8/8/2007 48 8/6/2008 13 10/20/2006 18 8/20/2007 100 8/26/2008 30 11/28/2006 6 8/23/2007 59 9/15/2008 32.5* 12/19/2006 5 9/6/2007 37 9/29/2008 27.5* 10/9/2007 63 10/31/2008 29 10/18/2007 94 11/25/2008 9 10/24/2007 47 12/30/2008 6 11/26/2007 7 12/20/2007 2 * = Average of two or more samples

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07020006-509 RCRCA Grab Sampling Data RR1 S001-679 2009 2009 2009 Date: Turbidity Date: Turbidity Date: Turbidity 1/21/2009 5 6/15/2009 27.5* 9/16/2009 35 2/24/2009 7 6/18/2009 41 9/24/2009 34 3/16/2009 26 6/26/2009 42 10/2/2009 40 3/24/2009 400 7/9/2009 40.5* 10/5/2009 50 4/8/2009 33.5* 7/15/2009 64 10/7/2009 70.5* 4/23/2009 32.5* 7/30/2009 23 10/8/2009 88 5/1/2009 18 8/4/2009 33 10/12/2009 20* 5/7/2009 12.5* 8/10/2009 38 10/22/2009 54 5/27/2009 13 8/21/2009 29 11/10/2009 31 6/2/2009 13 8/26/2009 40 11/23/2009 26 6/8/2009 27 9/3/2009 39.5* 12/4/2009 6.3 6/11/2009 33 * = Average of two or more samples

Site: TC4A – 07020006-504 – (S002-313) 07020006-504 TC4A RCRCA Grab Sampling Data S002-313 2003 2005 2006 Date: Turbidity Date: Turbidity Date: Turbidity 6/26/2003 25 3/31/2005 8 3/31/2006 90 7/31/2003 14 4/13/2005 23 4/4/2006 27 8/13/2003 18 4/14/2005 17 4/11/2006 15 9/29/2003 6 4/26/2005 8 4/25/2006 4 5/16/2005 15 5/15/2006 10 2004 5/24/2005 20 5/30/2006 12 Date: Turbidity 6/8/2005 38 6/12/2006 32 4/14/2004 7 6/27/2005 16 6/27/2006 33 5/5/2004 7 7/5/2005 15 7/10/2006 27 5/19/2004 11 7/29/2005 13 7/28/2006 36 5/27/2004 11 8/17/2005 10 8/2/2006 32 6/30/2004 9 9/13/2005 19 8/29/2006 27 7/27/2004 15 9/14/2005 39 9/12/2006 17

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8/23/2004 16 9/16/2005 23 9/26/2006 16 9/15/2004 20 10/17/2005 12 9/29/2004 15

07020006-504 TC4A RCRCA Grab Sampling Data S002-313 2007 2008 2009 Date: Turbidity Date: Turbidity Date: Turbidity 4/2/2007 39 4/8/2008 8 3/24/2009 140 4/5/2007 12 4/16/2008 120 4/8/2009 9 4/16/2007 22 4/18/2008 43 4/23/2009 19 5/3/2007 11 4/21/2008 37 5/7/2009 12 5/29/2007 28 4/28/2008 29 5/27/2009 18 6/13/2007 30 5/6/2008 14 6/4/2009 39 6/28/2007 10 5/21/2008 11 6/15/2009 36 7/5/2007 25 6/6/2008 52 6/18/2009 28 7/26/2007 49 6/9/2008 33 6/25/2009 31 8/8/2007 49 6/13/2008 58 7/9/2009 26 8/20/2007 150 6/26/2008 42 7/15/2009 37 8/23/2007 25 7/8/2008 45 8/4/2009 29 9/6/2007 23 7/31/2008 49 8/26/2009 7.2 8/6/2008 61 9/16/2009 8.4 8/26/2008 14 10/7/2009 9.7 9/15/2008 11 9/29/2008 18

Site: Marshall – 07020006-502 – (S003-702) 07020006-502 Marshall1 S003-702 RCRCA Grab Sampling Data 2009 Date: Turbidity 4/8/2009 11 4/23/2009 4 5/7/2009 4 5/27/2009 2.3

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6/4/2009 2.4 6/15/2009 3.1 6/18/2009 31 7/9/2009 40 7/30/2009 2.7 8/4/2009 5.9 8/26/2009 4.8 9/16/2009 6.7

Site: RWR-53 – 07020006-502 – (S001-199) 07020006-502 RWR-53 S001-199 RCRCA Grab Sampling Data 2009 Date: Turbidity 4/8/2009 17 4/23/2009 9 5/7/2009 10 5/27/2009 5.3 6/4/2009 2.3 6/15/2009 4.2 6/18/2009 15 7/9/2009 53 7/30/2009 3.8 8/4/2009 7.1 8/26/2009 2.6 9/16/2009 5.2

Site: CSMP 1210 – 0702006-503 – (S004-299) CSMP 1210 Citizen Stream Monitoring T- S004-299 Tube Readings (60 cm tube) 2006 Date: Centimeters Date: Centimeters 4/27/2006 16 7/21/2006 20 5/5/2006 19 7/28/2006 15

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5/18/2006 24 8/2/2006 15 5/25/2006 26 8/4/2006 15 6/2/2006 17 8/18/2006 16 6/9/2006 15 8/24/2006 10 6/16/2006 17 9/1/2006 11 6/23/2006 19 9/8/2006 9 6/30/2006 16 9/16/2006 25 7/14/2006 21 9/23/2006 29 10/6/2006 19

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Appendix C: Load Duration Curves

TMDL Section 5.3.1 Sample Site ID – RR1 STORET ID – S001-679 Hydrologic Unit Code (HUC) – 07020006-509

TMDL Section 5.3.2 Sample Site ID – Citizen Stream Monitoring Program (CSMP1210) STORET ID – S004-299 Hydrologic Unit Code (HUC) – 07020006-503

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TMDL Section 5.3.3 Sample Site ID – Marshall, RWR-53 STORET ID – S003-702, S001-199 Hydrologic Unit Code (HUC) – 07020006-502

TMDL Section 5.3.4 Sample Site ID – TC4A STORET ID – S002-313 Hydrologic Unit Code (HUC) – 07020006-504

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Appendix D: TSS Current Loading by Source: Methodology and Estimates of Relative Contribution

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Appendix E: Agendas, Presentations and Handouts

79 Redwood River Turbidity TMDL Report

Appendix F: Responses to Written Comments