Warning: This page is an edit and testing page use by the wiki authors. It is not a content page for the Manual. Information on this page may not be accurate and should not be used as guidance in managing stormwater.
Checklist for submitting the TMDL application form
What you will need
  • Identify applicable wasteload allocations(s)
  • Determine the method you'll use to calculate pollutant loads or load reductions
What you need if you are not meeting a WLA
  • List of practices you plan on implementing during the permit cycle
  • Estimated year when the practice(s) will be implemented
  • Estimated pollutant reduction during the permit cycle
  • Eestimated target year when the WLA will be met
What you need if you are meeting a WLA
  • List of structural practices implemented to meet the WLA
  • Geographic coordinates for the structural practices
  • Year the structural practices were implemented
  • Owner of the structural practice
  • Estimated reduction (e.g. pounds)
  • Method used to estimate the reduction

This page provides an example for filling out the Commissioner-approved form for permittees applying for Municipal Separate Sewer System (MS4) permit coverage and who have one or more Total Maximum Daily Load (TMDL) Wasteload Allocations for either total phosphorus (TP) or total suspended solids (TSS). The adjacent video illustrates this example. check

Determine the wasteload allocation

test image

dummy test page

It is necessary to first identify the wasteload allocation before determining if it has been met. TMDLs may provide a variety of information that can be used in meeting the permit requirement(s). The MPCA Master TMDL spreadsheet provides information that can be used by permittees to determine their WLA. Permittees may instead choose to determine their WLA(s) from TMDL reports.

For this example, assume a TMDL report provides the following information for City X.

  • Current phosphorus load = 500 lbs/yr
  • Wasteload allocation = 400 lbs/yr
  • Acreage contributing to impaired water = 800 acres

This data can be used to calculate the following.

  • Required reduction = 100 lbs
  • Required reduction = 20%
  • Current loading rate = 0.625 lbs/ac/yr
  • Target loading rate = 0.500 lbs/ac/yr

The WLA can therefore be expressed as any of the following.

  • An annual reduction of 100 pounds from the baseline year.
  • An annual reduction in pollutant loading of 20% from the baseline year
  • A loading rate of 0.500 lbs/ac/yr from the portion of the MS4 included in the WLA

Methods to measure progress and determine compliance

Permittees can demonstrate compliance with or progress toward meeting this WLA with the following approaches.

  • Using an appropriate water quality model to calculate the total load generated from the area of concern
  • Using an appropriate water quality model to calculate the loading rate (lb/ac/yr) generated from the area of interest
  • Calculating pounds reduced through implementation of stormwater control measures (BMPs or best management practices)
  • Calculating the percent reduction in pollutant load through implementation of stormwater control measures

Several tools are available to permittees to make these calculations. MPCA provides guidance for the following tools.

  • P8 water quality model
  • WINSLAMM water quality model
  • Minimal Impact Design Standards Calculator
  • MPCA Simple Estimator

Several other tools and models are available and appropriate and are listed here. If a permittee chooses a different calculation method or model, they should first consult MPCA Stormwater staff.

For this example, assume the permittee used the MPCA Simple Estimator and the Minimal Impact Design Standards (MIDS) Calculator.

Description of the Agency-approved form

screen shot of TMDL app form
Screen shot of the TMDL application workbook (spreadsheet). Click on image to enlarge.

The MS4 Phase 2 permit requires the permittee to submit a compliance schedule on an Agency-approved form. MPCA developed an Excel workbook that permittees use to comply with this requirement. The spreadsheet includes 6 tabs or worksheets, three that are used for reporting. The three reporting worksheets include the following.

  • A worksheet for permittees that are not meeting one or more WLA(s).
  • A worksheet where permittees claiming to meet one or more WLA(s) fill in information about implementation practices (BMPs)
  • A worksheet where permittees claiming to meet one or more WLA(s) fill in information on pollutant loads and methods used for calculating pollutant loading

The remaining three tabs are the following.

  • An introductory tab providing information on the workbook and links to guidance.
  • A worksheet containing all TMDL WLAs for all MS4 permittees. This worksheet includes the MS4 name and ID, TMDL WLAs for each MS4 permittee, the pollutant of concern, wasteload allocations, the baseline year as determined by MPCA, and for some WLAs the required reduction from the baseline year
  • A worksheet containing lists. This sheet is not visible or accessible to permittees.

Information worksheet

WLAs not met worksheet

BMPs for WLAs met worksheet

Documentation for WLA met worksheet

Master TMDL worksheet

Example 1 – Not meeting the wasteload allocation

screen shot TMDL app wla not met
Screen shot of the worksheet for permittees not meeting the WLA, from the TMDL application form. Click on image to enlarge.

For this situation, the permittee is not meeting their WLA. The permittee fills out the worksheet called WLAs not met. This includes the following information.

  • proposed BMPs or progress toward implementation of BMPs to be achieved during the permit term
  • the year each BMP is expected to be implemented
  • a target year the applicable WLA(s) will be achieved
  • estimated pollutant reduction to be achieved during the permit term and the Agency-approved method used to determine the estimate

There are two additional fields (columns) in the worksheet.

  • a description of the BMP. This field is optional.
  • The anticipated number of a specific practice to be implemented. This field is also optional and allows the permittee to lump similar BMPs rather than list each individually.

The example spreadsheet is shown in the adjacent image. Cells indicated in the following discussion correspond with this image.

Target year, estimated reduction, and reduction calculation method

The permittee enters data in rows 6, 7, and 8 to indicate, respectively, the estimated target year when the WLA will be met, the estimated pollutant load reduction during the current permit cycle, and the method used to calculate the estimated reduction. Columns B and beyond correspond with TMDLs for which a WLA is not being met.

Planned practices

Column A: To demonstrate progress toward meeting the WLA, the permittee plans the following practices and includes them in the Column A cells indicated below.

  • 12 bioinfiltration practices installed as part of a redevelopment project in 2022, selected from the dropdown list in Cell A12
  • a large underground infiltration practice in a new development in 2022, selected from the dropdown list in Cell A13
  • retrofitting a sand filter as an iron-enhanced system in 2021, selected from the dropdown list in Cell A14
  • enhancing the existing street sweeping program by conducting additional sweepings coordinated with fall leaf drop, selected from the dropdown list in Cell A15
  • establishing an urban forestry program designed to increase tree canopy coverage in the city by 25%, selected from the dropdown list in Cell A16
  • increasing the frequency of cleanouts for manufactured devices, selected from the dropdown list in Cell A17

Column B: This is an optional column used by permittees to provide more specific information about the practice(s) being implemented

The permittee chooses to evaluate compliance with the WLA by calculating pounds reduced using the MPCA Simple Estimator and the MIDS Calculator.

Notice: Only variables should be passed by reference in /var/www/stormwater-wiki/releases/20200904135518/skins/Mpca/Mpca.php on line 231

Privacy policy