Bevens Creek Turbidity Implementation Plan July 2013 Submitted by: Carver County Land and Water Services wq-iw7-33c ii Table of Contents Tables ............................................................................................................................................................ v Figures ......................................................................................................................................................... vi 1 Introduction ........................................................................................................................................... 1 2 TMDL Report Summary ....................................................................................................................... 2 2.1 Description of Impairments ............................................................................................................ 2 2.2 Development of the Flow Duration Curve ..................................................................................... 2 2.3 Calculation of TSS Equivalent for Turbidity Standard .................................................................. 3 2.4 Determining Loading Capacity ...................................................................................................... 4 2.5 TMDL Allocations for Individual Impaired Reaches ..................................................................... 5 2.5.1 AUID 07020012-717 ............................................................................................................ 7 2.5.2 AUID 07020012-718 ............................................................................................................ 8 2.5.3 AUID 07020012-523 ............................................................................................................ 9 2.5.4 AUID 07020012-514 .......................................................................................................... 10 3 Implementation Activities ................................................................................................................... 11 3.1 Introduction .................................................................................................................................. 11 3.2 Load Reduction Estimates ............................................................................................................ 11 3.3 Proposed Watershed Activities ..................................................................................................... 11 3.3.1 Urban activities ................................................................................................................... 12 3.3.1.1 Pond Design .................................................................................................................... 13 3.3.1.2 Piping .............................................................................................................................. 13 3.3.1.3 Volume Control............................................................................................................... 13 3.3.2 Rural Activities ................................................................................................................... 14 3.3.2.1 Wetland Restoration ........................................................................................................ 14 3.3.2.2 Conservation Tillage ....................................................................................................... 14 3.3.2.3 Buffer Strips .................................................................................................................... 15 3.3.2.4 Controlled Drainage ........................................................................................................ 15 3.3.2.5 Marginal Cropland .......................................................................................................... 16 3.3.2.6 Address Road Ditch Encroachment ................................................................................ 16 3.4 Proposed In-Stream Activities ...................................................................................................... 16 3.4.1 Bank Stabilization ............................................................................................................... 17 3.4.2 Stream Restoration .............................................................................................................. 17 3.5 Education ...................................................................................................................................... 18 iii 3.5.1 Workshops .......................................................................................................................... 18 3.5.2 Ongoing Publications .......................................................................................................... 18 3.5.3 Citizens Outreach ................................................................................................................ 18 4 Prioritization of BMPs and location .................................................................................................... 19 4.1 SWAT Modeling .......................................................................................................................... 19 4.2 Environmental Benefits Index ...................................................................................................... 20 4.3 Stream Assessment ....................................................................................................................... 21 4.4 Selection of management measures by stakeholder input ............................................................ 21 5 Plan Objectives and Budget ................................................................................................................ 23 6 Monitoring Plan .................................................................................................................................. 27 7 Adaptive Management ........................................................................................................................ 28 8 Citations .............................................................................................................................................. 29 Appendices ................................................................................................................................................ A-1 Appendix A: Stakeholder Group Meeting Minutes ................................................................................. A-1 iv Tables Table 2.3 TSS TMDL Load Allocations for Bevens Creek AUID 07020012-717 in kg/day. ............................ 7 Table 2.4 TSS TMDL Load Allocations for Bevens Creek AUID 07020012-718 in kg/day. ............................ 8 Table 2.5 TSS TMDL Load Allocations for Silver Creek AUID 07020012-523 in kg/day. .............................. 9 Table 2.6 TSS TMDL Load Allocations for Bevens Creek AUID 07020012-514 in kg/day. .......................... 10 Table 3.1 Estimated Concentration Reductions Based on Sampled Data and Flow Duration Curve. ....... 11 Table 4.1 BMP Preference Ranking based upon Stakeholder Group......................................................... 22 Table 5.1 Activities and tasks with associated estimated costs and priority for urban BMPs ................... 23 Table 5.2 Activities and tasks with associated estimated costs and priority for rural BMPs..................... 24 Table 5.3 Activities and tasks with associated estimated costs and priority for in-stream BMPs ............. 25 Table 5.4 Activities and tasks with associated estimated costs and priority for educational efforts ........ 26 v Figures Figure 2.3 Map of Bevens Creek and Silver Creek Segments. ...................................................................... 2 Figure 2.4 Bevens Creek Flow Duration Curve 1989 – 2007. ....................................................................... 3 Figure 2.5 Bevens Creek TSS/Turbidity Relationship (MCES, 2009) ............................................................. 4 Figure 2.6 Bevens Creek TSS Load Duration Curve. ..................................................................................... 5 Figure 4.1 Spatial Distributions of Simulated Annual Non-Point Source TSS Loads in Bevens Creek Watershed. ................................................................................................................................ 20 vi 1 Introduction Section 303(d) of the Clean Water Act requires that every two years states publish a list of waters that do not meet water quality standards and do not support their designated uses. These waters are then considered “impaired.” A total maximum daily load or TMDL must be developed for those impaired waters once they are placed on the list. The TMDL provides a calculation of the maximum amount of a pollutant that a water body can receive and still meet water quality standards. The state agency responsible for listing waters in Minnesota is the Minnesota Pollution Control Agency (MPCA). In 2002, the MPCA added Bevens Creek to Minnesota’s 303(d) list of impaired waters for an impairment of aquatic life due to turbidity levels in exceedance of the water quality target of 25 nephelometric turbidity units (NTUs) for Class 2B waters. A TMDL study was conducted by Carver County Water Management Organization (CCWMO) and approved by the Environmental Pollution Control Agency (EPA) in September 2012. This Implementation