MS4 Audits

The United States Environmental Protection Agency (U.S. EPA) requires Wisconsin Department of Natural Resources (DNR) staff to routinely conduct MS4 Audits to accomplish three primary objectives:

• Program Compliance –  Determine compliance with the MS4 Permit.
• Program Consistency –Gain a better understanding of the written municipal procedures at it relates to the permit and program implementation, both for the MS4 being audited (MS4 Permittee benefit) and for comparison against other programs statewide (WDNR MS4 Permit Program benefit). 
• Program Efficacy – Determine program effectiveness and improve operations to meet statewide water quality performance standards and targets established for local water quality planning efforts.

Although MS4 Audits are primarily conducted to assess and determine compliance with the MS4 Permit, MS4 Audits are beneficial in strengthening working relationships between the Department and MS4 Permittee. MS4 Audits serve as a significant learning opportunity to help clarify MS4 Permit requirements and help the Department gain knowledge about a MS4 Permittee’s operations, priorities, and storm water challenges.

To help prepare your community for an MS4 Audit, click below on each drop down and visit the MS4 Audit Preparation Checklist to learn more on the components of an MS4 Audit.

MS4 Audit Preparation Checklist : This Checklist is intended to be used as a tool to help prepare for an MS4 Audit by providing a series of questions. However, as MS4 Audits are routinely conducted, this Checklist may also be used by anyone interested in evaluating MS4 Permit Programs.

What does an MS4 Audit look like? 

DNR staff will contact the MS4 permittee to schedule an MS4 Audit. During this initial contact, department staff are available to answer initial questions, such as who should be present for the Audit, provide a brief description of the Audit process, and will request existing documentation be submitted for department review prior to the Audit (please see ‘Frequently requested documents for review’ drop down below). DNR staff will provide a draft agenda, which is sent to the permittee to confirm availability and meeting locations.

Note: If your community does not have any of the requested documentation, please do not create them for the purpose of the Audit.

MS4 Audits consist of in-office discussions and in-field inspections. Depending on schedules, the Audit is typically scheduled for one to three days. 

What is included in the in-office discussions?

• An overview of the MS4 Audit process is provided: For example, Department staff will explain that after completing the Audit, DNR staff will begin writing an audit report. If the Department needs clarification or has additional questions, this can occur during the writing period. Once complete, the department will send the final Audit report to the MS4 Permittee.
• Introductions: MS4 staff roles and responsibilities and how this relates to the MS4 Permit. 
• Questions: DNR staff will ask questions pertaining to the MS4 permit requirements such as the 6 Minimum Control Measures (MCMs) to understand the Permittee’s implementation of these programs. Ultimately, questions asked during the Audit are designed to assess permit compliance. 
  Please see the ‘Example Audit Questions’ drop down below for example questions asked during MS4 Audits.

What is included in the in-field inspections?

• The DNR requests in-field inspections for three primary reasons: 
  • To assess compliance and effectiveness of implemented actions, to determine if written programs and in-office discussions are consistent with observations, and to assess municipal staff implementing permit activities. 
  • For example, during an active construction site inspection, Department staff are assessing site conditions and assessing how the municipality is regulating the site (e.g., quality of inspections, inspection documentation, and communication with the site operator). 
• Below are more examples of common in-field inspections that may be included as part of an MS4 Audit:
  • In-field inspections for the Construction Site Pollutant Control Program: Ideally, two active construction sites one acre or more of land disturbance are inspected during the Audit. One municipal development (e.g., road reconstruction) and one private development. However, if there are no active municipal and/or private construction sites one acre or larger, Department staff may request a future inspection or inspect an alternative construction site.
  • In-field inspections for the Post-Construction Storm Water Management Program: During the audit, a municipally owned (public) stormwater BMP (e.g., wet pond, infiltration basin, etc.) is inspected. The MS4 Permittee should have staff responsible for conducting stormwater BMP inspections present, along with inspection reports used to document these inspections. 
  • In-field inspections for the Illicit Discharge Detection and Elimination Program (IDDE): A mock dry weather field screening at one of the MS4 Permittee’s storm water outfalls is conducted during the Audit. MS4 staff primarily responsible for conducting dry weather field screening inspections should be present along with the equipment used (e.g., testing equipment) and inspection report forms to document the results. 
  • In-field inspections for the Pollution Prevention Program: The Pollution Prevention Program could have a variety of different in-field inspections. However, most commonly, a municipal property requiring a SWPPP is inspected as part of the Audit. MS4 Staff responsible for conducting SWPPP property inspections should be present along with inspection reports used to document property observations. 
     

Who should be present?

Typically, municipal staff who are ultimately responsible for overseeing or are involved with the implementation of the MS4 Permit Programs (i.e., the Six Minimum Control Measures (MCMs)) should participate in an MS4 Audit. 

For many MS4 permittees, this person is clear, because they are the main person communicating with DNR Stormwater Staff (e.g., Director of Public Works or Village Engineer). However, municipal staff implementing certain aspects of the MS4 Permit (e.g., Public Works Superintendent responsible for directing winter road management activities) and/or externals assisting with MS4 Permit implementation (e.g., consulting firm engineer responsible for reviewing site applications for the MS4 Permittee) may also be beneficial.

However, because the person(s) responsible for different aspects of the MS4 permit tend to differ (e.g., the Village Engineer is involved with the Construction Site Pollution Control Program but not involved in the Public Education and Outreach Program), it’s common for MS4 Permittee representatives to change throughout the MS4 Audit. 

• For example, though the Village Engineer should attend the Construction Site Pollution Control Program discussions, they may choose to leave for the Public Education and Outreach Program discussions. If certain person(s) has limited availability during the MS4 Audit, MS4 Permittees are encouraged to communicate those needs so DNR Stormwater Staff can accommodate.

Frequently requested documents for review

• Written program procedures for each of the 6 Minimum Control Measures (i.e., Public Education and Outreach, Public Involvement and Participation, Illicit Discharge Detection and Elimination (IDDE), Construction Site Pollutant Control, Post-Construction Storm Water Management, and Pollution Prevention).
  • Please see the Storm Water Management Programs page to learn more about written program procedures.
• The most current MS4 Map 
• A current Post-Construction Storm Water BMP Inventory (includes municipally owned (public) and municipally operated (private) stormwater BMPs). 
• All Stormwater Pollution Prevention Plans (SWPPPs) for municipal properties require one and submit each property’s SWPPP inspection reports from the last 5 years. 
• Winter road management and/or maintenance procedures or plans. 
• If 5 acres or more of municipally owned land receives nutrients (i.e., such as municipally owned golf courses, athletic fields, etc.), submit the property’s nutrient application plans.
• Documents used to implement programs. Permittees may be requested to submit documents such as:
  • Permit applications are used for construction sites disturbing more than an acre of land (e.g., erosion control, stormwater management).
  • Internal checklists or similar documents are used to review construction permit applications and stormwater management plans for post-construction Best Management Practices (BMPs). 
  • Examples of recent municipally conducted erosion control inspection reports from an active construction site over an acre or more of land disturbance. Preferably the construction site that will be inspected as part of the Audit. 
  • Examples of recent dry weather field screening outfall inspection reports. 
  • Inspection and maintenance reports from one municipally owned (public) stormwater BMP from the last 5 years and its operation and maintenance plan. 
  • Municipally operated (private) stormwater BMP’s long-term maintenance agreement and supporting inspection and maintenance documents from the last 5 years. 

Example MS4 Audit questions

Below are examples of questions that may be asked by DNR staff during the MS4 Audit: 

• Can you describe the construction site erosion control plan review and permitting process for land disturbance greater than one acre or more?
• Who is responsible for compelling compliance at construction sites? If multiple people involved, please explain the process.
• Describe how your residents are made aware of MS4 permit issues/activities?
• Can you describe the post-construction BMP inspection procedures for publicly owned stormwater BMPs? Who is responsible for conducting these inspections?
• Has your community conducted maintenance on any public stormwater BMP in recent years? What kind of work has been done?
• Describe your dry weather screening procedure and the roles of staff responsible and the types of equipment used?
• How many municipally owned properties does your community have that require a stormwater Pollution Prevention Plan (SWPPP)? Who is responsible for conducting SWPPP inspections and how are they documented?
• For municipal properties which require a SWPPP— Can you describe, in general, the good housekeeping activities or best management practices installed to reduce or eliminate storm water contamination at the property?
• Have you evaluated the effectiveness of your program? If so, when was this last done, who participated in the evaluation, and what were the results?