Steve Carpenter, director of UW-Madison’s renowned Center for Limnology, took his first water sample from Lake Mendota in 1974.
Forty years later, Lake Mendota and the entire chain of Madison lakes continue to be a wellspring for his fresh water research.
Director since 2009, Carpenter oversees 10 faculty members, 60 year-round staffers and an additional 40 undergraduates who help with field work during the summer. About 90 percent of the center's budget comes from grants provided by federal or private sources. Last year, grant expenditures through the center were about $4.4 million.
In August, he and his team of researchers published a study that analyzed data sets collected from as far back as 1976. The study concluded that nearly 75 percent of Lake Mendota’s phosphorus load lands in the lake over 29 days each year.
At a time when Madison’s lakes have been listed on the Environmental Protection Agency’s list of impaired waters, the study could go a long way in helping government leaders, nonprofits and concerned citizens target the sources and methods of managing phosphorus-rich manure.
Originally from Kansas City, Carpenter spent much of his youth on his grandfather’s farm in Missouri. He attended high school in the Washington D.C. area before heading to Amherst College.
He found his way to Madison in the 1970s, earning his master’s degree and Ph.D. from UW-Madison. Upon completing his Ph.D. in 1979, he took a job with Notre Dame University.
Ten years later, he received a job offer from UW-Madison’s limnology department, an offer he says “any limnologist is going to take.”
“It’s the most exciting place to be, with the best program in North America,” Carpenter says.
Carpenter recently sat down with The Cap Times to talk about how the Center for Limnology’s latest study can be used to clean up the lakes without stifling agriculture and how he is optimistic the human species will solve the “most severe environmental challenges” it has ever faced.
The Capital Times: You mentioned at the start of the interview that an offer to work at the university’s limnology department was too good to pass up. What makes this program so special?
Steve Carpenter: Limnology started in the United States in 1875 at UW-Madison. It has been a huge part of the university ever since.
The Center for Limnology consists of two field stations: the Hasler Laboratory on Lake Mendota and Trout Lake Station in Boulder Junction, Vilas County. In regards to the prominence of the university’s program, Trout Lake Station is probably one of the most famous field stations in limnology in the country and probably one of the most lake-rich regions of the work. There are 1,800 lakes within an hour drive of the station.
Most of our research occurs within an hour's drive of those two sites. We also work on both of Wisconsin's Great Lakes and the Wisconsin and Mississippi Rivers.
You describe the study results published in last month’s Aquatic Sciences journal as staggering. Do you consider the results encouraging for local efforts to reduce phosphorus levels by half in local lakes by 2025?
I do. We now know we don’t need to be out there every day. We just need to figure out what it is about those 29 days and try to deal with those conditions.
Why are those 29 days so prone to phosphorus runoff?
On those days, two things come together. One is a lot of water on the land. That can either be snow melt or rain. The second thing you have is a lot of phosphorus on bare soil. The phosphorus mostly comes from manure. It could also come from fertilizer or just phosphorus-rich soil that has been tilled. These conditions typically combine in springtime.
No longer allowing farmers to spread manure during that 29-day time frame seems like a no-brainer to fix the phosphorus runoff from farmland, is it not?
Absolutely. I think there is pretty widespread agreement on that. I’ve even heard farmers say that what really needs to happen is getting manure off the land in February, March and April. The way to do that is to put it in storage facilities, to use manure digesters or to have less cows, and that is driven by economics.
But storing manure is only a temporary solution.
Correct. You still have to get rid of it some way … either digest it or put it on the land at a time when the land can actually use it and maybe absorb it. The trouble with putting it on our land is our land already has a lot of phosphorus on it. The capacity of the land to absorb more is pretty limited in the watershed. We are really going to have to go to digesters. I think that is just going to become part of the cost of doing business.
Where do you go from here with the information?
We have a healthy relationship, for example, with the folks at the Clean Lakes Alliance, the Dane County executive’s office and the Dane County Lakes and Watershed Commission. We meet with them frequently and I believe they feel they can email or call us anytime.
Milwaukee-based We Energies has submitted a rate filing change to the state's Public Service Commission that would drop the buyback rate for new customer-sited bioenergy projects — like food and manure digesters — from 9.2 cents to 4.24 cents per kilowatt-hour. How do we make the economics of a digester work?
I am not a businessman or a politician. But I think there are people in Dane County offices and the Clean Lakes Alliance who are thinking about these things.
I do know the price of methane gas produced by digesters is low right now. We have a big supply in the United States largely due to the fracking industry and an export bottleneck. Once the export bottleneck is solved, then our prices within the U.S. will float up to the global price. But right now, natural gas is really cheap in the United States and biogas (from digesters) is natural gas. I suspect that is what is prompting the rate request change.
What’s next for your team?
The next big thing we are doing is the water quality projections for the Yahara 2070 scenarios. These are four stories about the future of Madison out to 2070. We want to know what lake water quality will be like in each of those four stories. We have developed computer models that will generate water quality out to 2070 for the four Madison lakes — Mendota, Monona, Waubesa, Kegonsa. The scenarios will probably come out in about one year.
What do you see as hope for the future?
I see three reasons to be optimistic that we are eventually going to solve these water quality problems.
One is that that technology is really moving along and it is getting better and better. We live in a very sophisticated region of the United States for technology and science. We are in a good place to bring the best science and engineering to the problem.
The second thing is that people really care about it and they are telling the government to do something about it. And government is doing something about it. We have a very engaged county and municipal governments and they are doing a lot.
The third thing is there a growing awareness among people that the way they live their lives really does affect the world around them. They are paying attention to the way they consume resources to try and make the environment better.
You describe the challenges we face as unprecedented, though.
Our world is definitely facing the most severe environmental challenges our species has ever faced. But we haven’t gotten by for three million years as a species by being bad at facing challenges. We are great at facing challenges. But we really do need to buckle down and pay attention to the current cluster of environmental challenges. And I think we will.