In March 2011, an American environmental scientist, Stephen Carpenter of the University of Wisconsin-Madison, won the Stockholm Water Prize. It’s given each year to someone who’s worked to improve the state of the world’s water resources. Carpenter’s focus – freshwater lakes. He told EarthSky:
I have focused particularly on the over-enrichment of freshwater with nutrients.
That is, runoff from farms into lakes. Dr. Carpenter has studied the American Midwest for nearly 40 years. These lakes suffer from an influx of nutrients from fertilizers and manure. Carpenter said:
Pollution of rivers and lakes and reservoirs with those materials lead to blooms of toxic algae, loss of oxygen, fish kills and related problems.
Dr. Carpenter tries to address these problems at their source – the farmer’s fields. He said the major culprit, at least in the upper U.S. Midwest, is manure and over-fertilization – people using way too much fertilizer on the land. He said:
Decreasing fertilizer use is mainly a matter of giving farmers accurate information about how much fertilizer they need often they don’t need to spend so much money adding fertilizer, once they know that, they’ll add less.
The manure problem is much harder to deal with, because this is dairy country and there’s a lot of manure up here, and it’s a waste product that farms have a difficult problem disposing of. We have worked to develop manure containment facilities, for example, that keep the manure from running off, there are certain times of year when it is much more harmful to apply the manure to land, and we try to identify those times of year. Right now we’re experimenting with manure digesters that actually convert the manure to natural gas, which makes energy.
The manure problem is hard to deal with, said Carpenter, because Wisconsin is dairy country. Image credit: Royalty-free image collection
A number of Wisconsin lakes have restored health – more big fish, fewer toxic blooms – thanks to Dr. Carpenter’s work. He explained why he thinks his team has been able to take their scientific work from theory, into community practice:
I think an important part of what we do is to help people understand that no one really understands. These huge complex systems, and anything we try is to some degree experimental. But doing something is way better than doing nothing.
Dr. Carpenter said that another vital part of his work with Wisconsin’s lakes involves collaboration with fisheries managers and the general public, to control what’s being fished in local lakes. He said:
Fisheries are managed by setting limits on the sizes of fish that can be removed, and on the numbers of fish that can be removed. If the size limits are adjusted so that only the very largest fish are removed – in other words, you cant take a fish unless it’s a very big one – then the effect is to increase the overall size of the individual fishes in the population, you end up with a lot more big fish. You end up with more grazers, and less algae.
He said that no two technological solutions for lake pollution across the world look exactly alike.
Technology is basically the application of human knowledge to solve a problem. In many cases, these are just farming smarter in a given place.
For example, in Wisconsin, there are ways of using manure on farms that increase the water-holding capacity of the soil, so those methods decrease flooding, wastage of water, and they decrease runoff of nutrients. A simple thing, but it has to be developed region by region. The practices that work for Wisconsin are probably not the practices that will work for Arkansas. It takes a lot of local work but it can be done.
Dr. Carpenter added that local lake problems add up to global ones.
I think the biggest issue facing freshwater, globally, is agriculture. Agriculture is the largest consumer of freshwater among human activities. It is the largest polluter of freshwater among human activities.
Agriculture is also one of the largest drivers of climate change, he told EarthSky.
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