In May, Lake Champlain hit a record high, 103.5 feet above sea level in Whitehall, N.Y. The previous record, 102.1, was from 1869. Destroyed houses, plumes of sediment and garbage, and swamped roads drew dismay, amazement and worry -- and a lot of media attention. Now the floodwaters are receding, clean-up is under way and the TV cameras have turned to other matters. But the causes of the flood -- and future prospects for the lake -- remain murky. To get a deeper picture of the 2011 flood, UVM Today spoke with four scientists on the UVM faculty about where the flood came from -- and what comes next for Lake Champlain.
Lesley-Ann Dupigny-Giroux, associate professor of geography and Vermont state climatologist
To get a grasp on what’s happened we have to go back to the beginning of the winter. Two large-scale atmospheric patterns came together and helped steer some of the storms we got.
We were in a strong La Nina pattern -- the cooling of the Pacific Ocean that tends to create a dip in the jet stream and steer storm systems over the eastern part of the country. We were also in a strong negative North Atlantic oscillation pattern, which also sets up a dip in the jet stream. Each can produce a snowy winter, but this year, both configurations tended to reinforce each other, producing extensive snowpack and depth -- it started to warm up and the snow had to go somewhere.
Plus, we didn’t have a January thaw -- that could have alleviated a little. Then we got into spring and what we call a reactive weather pattern, one cold front after the next moving through, producing record-breaking rainfall. We broke at least 20 different records in terms of individual days, in some cases over 4 inches in one day.
And a lot of our major streams run north and then west -- much of that precipitation fell over the headwaters in the central and northern parts of the state. So the geography of the state contributed in terms of moving water from the Green Mountains towards the Lake Champlain basin. Looking at it from an entire systems perspective, it was the perfect recipe for flooding.
Paul Bierman, professor of geology
The flood is over -- for now.
I had one master’s student who looked at flow records for the Winooski River, lake level records, and precipitation records for this part of the world. He found a 10 to 20 percent increase in the amount of precipitation over the last 80 years or so. It’s gotten wetter in Vermont over the last century, so there so is more water coming down the Winooski. It doesn’t take much to put those two together to say that there is going to be more water coming into Lake Champlain.
It’s climate change. What we’re seeing is consistent with many models that suggest increased hydrologic activity. You heat up the system and more water is going to be evaporated and more water is going to rain out.
I hope we look at this new flood level as the level of hazard and try to make sure that at least new things are built above this 103-foot or 103.5-foot level.
My gut is that we might see more of this in the future: the climate is getting warmer, the hydrological cycle is getting more intense. I would hope that what we take away from this is, if possible, relocating some of this vulnerable infrastructure. In most years, the lake is toying around 100 or 101 feet, and there is some damage.
What do we have: about 100 years of records on rain gauges for Lake Champlain? It is the highest flood of record on those gauges. But we don’t know, going back pre-historically, what the high flood levels are.
But from a responsible municipal planning perspective, we know that big floods can happen now. And all scientific suggestions are that we’re going to see more rainfall and runoff. It would seem to make sense in the rebuild process to respect the fact that the lake can get over 103 feet. Putting things at 101 is begging for trouble.
Donna Rizzo, associate professor of environmental engineering
Our statistics for 100-year storms -- they’re all wrong! We should expect these kinds of floods more often.
I tell people: you should not build in flood plains, don’t build too close to the lake. I know it’s beautiful prime property, but you’ve got to respect Mother Nature especially given what we’ve done with climate change. We’re going to get more erratic storm events.
This year, based on sediment transport, it’s going to be interesting to look at the algae blooms. We’ve never seen this kind of sediment transported -- and the phosphorus levels in soils throughout the state are so saturated. Where I do a lot of work on the Winooski River, seventy-seven metric tons of phosphorus was measured in one week this spring. That’s half the typical annual load! I truly believe we are in for big algae blooms -- but we don’t know if they’ll be toxic. Still, I’m not going to swim in the lake this summer.
The circulation patterns haven’t changed that much because the weather hasn’t changed that much, and the wind is what is usually directing the circulation patterns in the lake. But no one understands the processes that control the lake -- we’re still trying to figure out what triggers these algae blooms. It’s not clear why one year the blooms are toxic and one year not.
A flood like this is fascinating from a complex systems perspective. I don’t want to say, “Oh, great, a huge storm event!” But, still, if you don’t see these kinds of extreme events, it’s almost impossible to even test hypotheses. To have data from these kinds of years is invaluable for building models.
This flood data will help my models become more robust, more predictive. Granted, these are statistical models, not process models. I don’t think we’re even close to being able to make good processed-based physics models of these kinds of ecosystems.
In some ways, we have a new lake here. We just reset boundary conditions with all the sediment that we just poured in. There will be a different ecosystem. Why is that bad? It’s bad only because we’ve built up an economic system around the ecosystem that existed. We’re going to have a different, probably very beautiful ecosystem. It’s our man-made infrastructure that’s in trouble.
And this is just the beginning. It’s scary if you go into all the climate change reports and look at the amount of infrastructure damage that is predicted from just one or two degrees Celsius increase over the next 50 years -- which we know we’re in for. We’re pretty certain that we’re going to be without a huge percentage of airports and railways, for example. We can’t fix all of it so we’re going to have start setting priorities. We’re going to find out soon what is important to people.
Ellen Marsden, professor of fisheries
We were out a lot doing field work during the high, high water -- when we could find a ramp where we could get our boat out. Wow. All these homes up to their eyeballs in water. Ow.
When we say, “Oh, it was a devastating flood,” what was is it devastating to? Not the ecology. The ecology, honestly, was fine. The fish had a bit more water to swim in. The bugs had a few a more lawns to colonize. Most of the biology is having a great time out there. It’s devastating because we built in its way. It’s the same in the Mississippi. You build in a flood plain and it floods. But that’s not something anyone likes to hear; we like to be near water.
There are two effects from this flood in the lake: one natural, one human. Anytime there is a flood there is, obviously, water coming at high velocity and high volume. It’s bringing lots of sediments and lots of nutrients -- perfectly normal nutrients. The sediments are pretty rough on a lot of aquatic organisms. We know that silt is bad: it clogs gills and fish eggs. It clogs spawning areas. It’s just a bit more silt in a flood.
Floods happen every year -- and this one is extreme -- but you’ve got an entire community of insects and other organisms attuned to floods and adapted. In a high flood, some will benefit -- and some will benefit when it’s low. From a fish’s perspective, the fact that there is six more feet of water is simply six more feet of water. Cool!
The scary effect is the amount of stuff that people had in their garages and basements and sitting on their property that floated out into the lake, spilling contaminants: the paint cans and the portapotties floating downstream. That’s just nasty stuff. The human economy and contaminants are the real tragedies.
I tend to be pretty philosophical about this: lakes change, banks fall into the water, trees fall over. A lot of these happened quite suddenly in this flood, but this is normal. It’s not a like tsunami which is a very extreme natural disaster. This flood is a very un-extreme natural disaster!
A lot of the fish that spawn in the late spring--when most of this water was very high -- have a quick reproductive turnaround. Even a slow species, like walleye -- it’s only in the egg stage about 21 days. So by the time that the flood started to subside the chances that they got left high and dry by the flood are pretty slim. Presumably there are some fish that got a little too close to shore, but not a huge number. I’m not ready to predict that this flood will be disastrous for any class of fish.