Barbara J. Huberty: Stormwater ponds aren't a financial liability

The March 9 Post-Bulletin's Outdoors Page featured a column by naturalist Greg Munson entitled "Are stormwater ponds financial time bombs?" I'd like to correct several inaccuracies contained in that column and present "the rest of the story" from a Public Works storm water management perspective.

Munson expressed his concern about expensive pond cleanup projects (aka dredging) due to sediment contaminated by polycyclic aromatic hydrocarbons, but his argument was based on data for the metro area, assuming landfill disposal costs.

So far, those concerns have not proven to be true for Rochester.

Ever since the Minnesota Pollution Control Agency developed dredging guidelines for storm-water ponds, the city has been testing sediment before dredging to determine what can be done with it. We must follow state regulations that set threshold values identifying whether dredged sediment can be reused anywhere, must be confined to industrial areas or landfilled.

To date, our sediment-testing results have indicated the sediment quality has been suitable for reuse without restrictions. Typically, we either reuse the sediment on site to improve grading and drainage or reuse it as fill on construction sites.


I also would like to clarify that because ponds improve water quality for the benefit of all citizens, pond construction and maintenance costs are co-funded by developers (through the development fees that are paid at the time of development) and by property owners through their monthly storm-water utility fees. Storm-water work is not funded through property taxes.

There are 355 storm-water quality treatment ponds located throughout the city, not 500. Fifty-two percent (185 ponds) are the responsibility of the city to operate and maintain. Six are managed by Olmsted County, 33 state ponds are managed by Rochester Community and Technical College and by the Minnesota Department of Transportation, and 131 ponds are privately owned and maintained.

These ponds were not installed as part of a mid-1980s "craze" — their construction began and will continue in response to requirements of the Federal Clean Water Act and the MPCA.

As long as routine sediment-removal activities restore initial design capacities, a pond's useful lifespan is unending, not a mere 25 years. It has been hypothesized that the timespan between dredging events is 25 years, but that theory won't be validated until several decades of experience occurs. Only 10 percent of ponds managed by the city have been dredged so far, so we are a long way from understanding true lifespans.

Rochester's decision to not pursue a ban on coal tar-based sealants was not related to the absence of PAHs in our sediment or on the cost of sediment disposal; rather, it was because there are other state and national government and industry initiatives already under way that will achieve the same effect.

The best defense for preventing unwanted sediment contamination in storm-water ponds is a good offense — helping people understand that their actions on the land impact water quality. Not only should property owners use asphalt-based sealants instead of coal-based sealants, they should exercise caution when applying any chemical to the ground surface.

So please, compost leaves and grass clippings, never overuse fertilizers and pesticides, fix vehicle leaks, and properly inflate your tires to reduce wear.

To learn more about storm water management in Rochester, go to .


Barbara J. Huberty is the Regulatory and Environmental Affairs Coordinator for the Rochester Public Works Department.

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