Contributed by Annie McIlwain P.E., Principal and District Manager, PPM Consultants
Industrial stormwater compliance is one of those topics that is pretty much guaranteed to never go away, and in Mississippi it is very much back in the spotlight. Mississippi’s Storm Water General Permit for Industrial Activities has expired and is currently under review and revision by the Mississippi Department of Environmental Quality (MDEQ). Don’t worry—you didn’t forget to send in an application. Until a new permit is issued, the existing permit remains in effect and enforceable. Facilities should be watching for “recoverage forms” once the final permit is released, which will ensure continued coverage under the new permit. That said, paperwork alone has never kept a facility in compliance.
A common question I hear is whether it makes sense to wait until the new permit is issued before updating a Storm Water Pollution Prevention Plan, or SWPPP (“swip,” as we tend to call it). From a practical standpoint, waiting is rarely the best option, especially if your SWPPP has not been updated in any meaningful way for a while. While the revised permit has not yet been issued, it is reasonable to expect that SWPPP requirements may change slightly, be clarified, or be emphasized differently. When that happens, facilities will need to compare the new permit language directly against their existing SWPPP and make updates where needed. Facilities that already have a solid, up-to-date SWPPP are usually in a much better position to handle those changes quickly and without a lot of scrambling.
Also, in the meantime, the current general permit still applies. MDEQ inspections and enforcement do not pause just because a permit is under review. This makes now a good time for facilities to take an honest look at their SWPPP and ask a simple but sometimes uncomfortable question: does this document actually reflect how stormwater is managed at the site today, and does it meet existing permit requirements?
Common SWPPP Deficiencies
In our experience working with industrial facilities across the Southeast, the answer is often “not entirely.” SWPPPs are usually written when a facility is first permitted and then slowly drift out of alignment as operations change. New storage areas are added, drainage patterns shift, or processes are modified, and the SWPPP never quite catches up. No one means for this to happen, it just does.
Outdated site maps and descriptions are among the most common issues we see. We have walked sites where the SWPPP shows a single outfall, but multiple outfalls are clearly present in the field, or where material storage areas have moved but the map still reflects a layout from years ago. These issues are rarely intentional and are usually the result of day-to-day operational changes happening faster than documentation updates.
Another frequent issue is how potential pollutant sources are identified. Many SWPPPs rely on generic language that technically checks the box but does not really describe what is happening on site. Outdoor storage, loading areas, waste handling, and equipment maintenance are all common sources of stormwater exposure, yet they are often described in very broad terms. When regulators review a SWPPP, they are looking for a clear connection between site activities and stormwater controls. If that connection is weak on paper, it usually leads to more questions in the field.
Best management practices (BMP) can also drift out of sync with reality. BMPs may be listed in the SWPPP but not consistently implemented, or good controls may exist on site but were never added to the plan. We have also seen the opposite where facilities have made real improvements over time but forgot to update the SWPPP to reflect them. Unfortunately, if it is not documented in the SWPPP, regulators may assume it does not exist.
Inspection, monitoring, and training requirements create additional challenges. Missing inspection records, incomplete corrective action documentation, and sampling results that are collected but never really reviewed are common findings. Training records also tend to lag behind, especially at facilities with staff turnover, and it is not unusual to see SWPPPs that still list personnel who left years ago.
How Can I Ensure My Facility’s SWPPP Is in Good Shape?
As Mississippi moves closer to issuing a revised Storm Water General Permit for Industrial Activities, facilities should expect to review their SWPPP line by line against the new permit once it is released. That comparison often reveals gaps that were easy to overlook under the old permit. This is where outside support can be helpful. Here at PPM, we regularly assist facilities with SWPPP updates, SWPPP audits, and permit-to-plan comparisons to help ensure stormwater programs are practical, current, and defensible.
Ultimately, a SWPPP should be more than a permit requirement sitting on a shelf collecting dust. It should function as a living document that reflects real site conditions and evolves as regulations and operations change. Addressing common deficiencies now can make the transition to the new permit much smoother and reduce the likelihood of unpleasant surprises during inspections.
Please reach out if you need any stormwater assistance or have any questions. We are here and happy to help! Feel free to email me at annie.mcilwain@ppmco.com.