For the past few years we’ve been hearing about how our rain events in Minnesota have been changing. More rain, more intense rainfall patterns, flooding damages, and even fish kills from extreme storm water runoff in agricultural areas (Southeastern Minnesota Coordinator Anna Richey wrote about rainfall-related fish kills last October). I certainly see the effects of these changes in the East Metro cities I work with, especially in Shoreview, where all of the city’s seven lakes are at high levels. In fact, this past summer an entire road in Shoreview was submerged for a couple of months. The road, Gramsie Road, had to be raised by two feet in order to bring it out of the water. The city handled the road flooding incredibly well, relying on expertise from their public works staff, the city engineering staff, and the Ramsey Washington Metro Watershed District.
The Gramsie Road situation demonstrates the difficult infrastructure challenges Minnesota cities face with changing weather patterns. I wanted to learn more about this from a city public works perspective, so I spoke with Mark Maloney, Shoreview Public Works Director and Chair of the Water Supply Technical Advisory Committee, which serves the Metropolitan Council, to learn more about how he and those in his profession are modifying their practice to better fit our changing climate.
Storm water infrastructure: who controls that?
I began by asking Mark about the role of a city in responding to storm water overflow events. He explained that the city’s role is part of a very layered approach in Minnesota. Oversight and problem-solving comes from the Department of Natural Resources, the Board of Water and Soil Resources, conservation and watershed districts, city government, and of course landowners. However, the city does own and operate the storm water drainage infrastructure and anything covered under the MS4 permit (MS4 permitting refers to municipal storm sewer management requirements). Mark emphasized that solutions to surface water problems are sometimes well beyond any one agency, so they require time to work with partners to get things right.
Not the rainfall we’re used to
Mark delved into the matter at hand: changing precipitation. He explained that many metro cities were developed in an era that referred to very different weather data than what we have now. Most cities like Shoreview were built with reference to a precipitation modeling data set referred to as TP40, or Technical Paper 40, which uses rainfall data collected up to only 1961. The data from TP40 tells us what amount of rain could be considered a 100-year rainfall event or 1,000-year rainfall event. So when you hear that “1-in-100-year-rain” phrase in the news, that’s where it comes from. According to Mark, this now-irrelevant data set was used in development until a just couple of years ago, yet Mark says, “most people agree that precipitation data might look a little different from 1961-forward.” Mark clarified that we aren’t receiving more total rainfall annually; we’re just receiving more intense and regionally-focused rainfall events.
There is a new data set, however. It’s called ATLAS14 and it adds on to the 1961 data with new observations of precipitation trends as well as projections of precipitation changes. The problem is, we still have cities that were built based on a prior data set. New development designs use better data and assume different rainfall patterns, but in most areas we’re stuck with old infrastructure that we now have to modify.
This isn’t meant to be a grim picture of catastrophic changes, but it is meant to showcase how everyday aspects of our lives – as basic and fundamental as the storm water system under our feet at this moment – are disturbed by new rain patterns. This can inconvenience residents and change daily activities. In Shoreview, there hasn’t been any residential structural flooding, but as Mark puts it, “the main issue is that there’s water where people don’t want it, especially around the lakes.” When Gramsie Road flooded, 4,000 cars a day were redirected to different routes through the community. Plus, Shoreview is an active community with trails, lake recreation, and many lakefront property owners. People may notice precipitation changes more easily than other areas in the metro. They lose access to trails, and boat owners may be affected by “no wake zones,” which Shoreview has had to issue in light of the high water levels.
The take-away: changes are complex and expensive
Talking with Mark Maloney means receiving a wealth of information on city water infrastructure. It’s a delight! But I felt that we needed a concluding statement – something to put the cap on our lesson learned here. Here’s what he had to say when I asked him for exactly that.
“The fact is, we’re in a very different weather pattern now. Based on what we were observing from 1961, a 1-in-10-year storm is now happening every other year. We’re living with decisions made in the 60s and 70s, when land was different, and frankly when the climate was different. The challenge is, we have to go back into residential areas built in a different time and we now have to retrofit them. It is very difficult to change things that are already set. Solutions are going to take more time and more money than we thought – much more money than cities anticipated in prior planning and utility modeling. For example, we never anticipated what happened at Gramsie Road.”
We’re lucky to have people like Mark working on our most challenging infrastructure problems. I want to emphasize how well the city of Shoreview and the Ramsey Washington Metro Watershed District worked together to analyze water flow and create a solution for Gramsie Road. I have a feeling watershed districts are going to become more important than ever in working on these issues. Minnesotans are resilient, and our cities can address storm water challenges creatively and successfully in the years to come. However, it will take financial resources and strong communities that acknowledge that rain patterns have changed significantly in the past half of a century. We need to work with cities and state government to develop solutions, and where possible we need to promote renewable energy sources to curb these rain pattern changes.