TURBIDITY TMDL PROTOCOLS AND SUBMITTAL REQUIREMENTS Prepared by the Turbidity TMDL Protocol Team: Greg Johnson, Nick Gervino, Larry Gunderson, Louise Hotka, Molly MacGregor, Mike Vavricka, Bill Thompson, Lee Ganske, Maggie Leach, Tom Schaub, Chris Zadak, and Jim Klang Minnesota Pollution Control Agency March 2007 Turbidity TMDL Protocol Guidance and Submittal Requirements Contents I. Introduction A. Purpose.......................................................................................................................1 B. Protocol Structure ......................................................................................................2 C. Overview of the TMDL Process................................................................................7 II. Methodology for Developing Turbidity TMDLs A. Basic Principles and Concepts i. A Balanced Stream Ecosystem ......................................................................9 ii. Turbidity Interactions.....................................................................................10 iii. Turbidity Stressors (Stressor Parameter Education .......................................18 1. Natural Sources..................................................................................19 2. Anthropogenic Sources......................................................................19 a. Point Sources .........................................................................19 b. Nonpoint Sources...................................................................20 iv. TMDL Goal Setting .......................................................................................23 B. Beginning the Project – Problem Definition..............................................................28 i. Advisory Committees ....................................................................................29 ii. Applicable Water Quality Rules ....................................................................29 iii. Initial Problem Assessment............................................................................30 iv. Comprehensive Data Compilation from Existing Sources ............................32 v. Data Review and Evaluation..........................................................................36 1. Prominent Data Gaps .........................................................................40 2. Stressor Identification ........................................................................40 3. Critical Conditions.............................................................................41 vi. Data Gaps Identification and Plan to Fill the Gaps........................................42 C. Source Assessment and Analysis Needs....................................................................43 D. Additional Data, Monitoring Needs...........................................................................46 E. Analysis and Modeling i. Select Analysis Framework 1. Basic Objectives.................................................................................46 2. Selecting an Appropriate Analytical Tool .........................................47 3. Tools/Models Available.....................................................................47 4. Use of the Tools/Models Available ...................................................50 ii. Additional Data Acquisition to Support Analysis Framework......................51 iii. Model Set Up and Evaluation........................................................................51 iv. Model Application and Example TMDL components...................................54 wq-iw1-07 Minnesota Pollution Control Agency i Turbidity TMDL Protocol Guidance and Submittal Requirements III. Turbidity TMDL Submittal Requirements F. Minnesota’s Checklist................................................................................................56 G. Detailed Submittal Requirements for Turbidity TMDLs...........................................58 i. Identification of Waterbody, Pollutant of Concern, Pollutant Sources, and Priority Ranking.............................................................................................58 ii. Description of the Applicable Water Quality Standards and Numeric Water Quality Target ................................................................................................59 iii. Loading Capacity - Linking Water Quality and Pollutant Sources ...............61 iv. Load Allocations............................................................................................63 v. Waste Load Allocations.................................................................................63 vi. Margin of Safety ............................................................................................68 vii. Reserve Capacity ...........................................................................................69 viii. Seasonal Variation .........................................................................................71 ix. Reasonable Assurances..................................................................................71 x. Monitoring Plan to Track TMDL Effectiveness............................................74 xi. Implementation ..............................................................................................76 xii. Public Participation........................................................................................78 xiii. Submittal Letter .............................................................................................81 xiv. Administrative Record...................................................................................81 III. Site Specific Approaches...............................................................................82 IV. References..............................................................................................................82 V. Appendices A. MPCA Development Activities for Typical Projects………………………………………84 B. Background of the Minnesota Turbidity Standard.....................................................86 Figures 1. Flowchart for the Turbidity TMDL Study and Attainment Strategy.............................4 2. Turbidity Sources and Stresses by Type of Material in Water ......................................23 3. Simplified Nonpoint Turbidity Conceptual Model........................................................24 4. Iterative TMDL Process.................................................................................................74 Tables 1. Key to the Flowchart in Figure 1 ...................................................................................5 2. Turbidity Parameter and Method Codes........................................................................15 Minnesota Pollution Control Agency ii Turbidity TMDL Protocol Guidance and Submittal Requirements I. Introduction A. Purpose The purpose of this Turbidity Total Maximum Daily Load (TMDL) protocol is to provide a common understanding between TMDL project team members and reviewers of the expectations, requirements and science principles used in completing a turbidity Total Maximum Daily Load study and following report. This document outlines both the science and the steps needed for approval by the Minnesota Pollution Control Agency (MPCA) and the United States Environmental Protection Agency (EPA). The protocol is a discussion of the key questions to be asked, and an overview of the principals and other technical references to be used as a basis to discover the answers, not a cookbook formula. The organization of this document is to provide you a science baseline on how and what are the typical key pollutant and physical parameters that commonly affect turbidity levels. Included in the discussion is an organizational layout for your investigation to be used to validate or eliminate the potential stressors. This layout can be used as a general outline to develop your investigation in the stages of monitoring, contract work plans, and communication of the results. This protocol is intended to build confidence and uniformity between the expectations of the TMDL project team and reviewers for determining stressors, evaluating needed expenditures, understanding project reporting requirements, and the TMDL project approval process itself. A significant source of the organizational layout is based upon the concepts provided in the EPA guidance manual on “Stressor Identification” for Biotic Impairments. This manual can be found on line at http://www.epa.gov/ost/biocriteria/stressors/stressorid.pdf. It provides useful techniques that can be applied in all TMDL projects, and should be strongly considered for any investigation that is sorting through multiple potential stressing pollutant parameters and/or multiple sources of pollutants. This process also blends well with the public involvement process the MPCA promotes for a TMDL project’s team. When the advisory teams for a project use the stressor identification and weight of evidence concepts routinely in their meetings, it can build common assumption bases quicker and has a better chance of developing conclusions that have a broader consensus in the group. Minnesota Pollution Control Agency 1 Turbidity TMDL Protocol Guidance and Submittal Requirements B. Protocol Structure The protocol is written as an educational document to foster the development of technical skills required for watershed management regarding turbidity, ultimately to provide for a healthy ecosystem. As such, a reader familiar