Alan Roberson's pond traps sediment. Before the pond was built, silt washed into a creek and caused problems farther downstream. (Photo by Lester Graham)
Since the dust bowl days of the 1930s Depression, the government has been working with farmers to reduce erosion. Today, soil conservation is better. But fields still lose a lot of topsoil because not all farmers use the best conservation methods. Dirt is washed away by rain. That silt clogs up streams, rivers and lakes. But one region is trying to intercept the silt before it gets to the river system. The GLRC’s Lester Graham reports:
Transcript
Since the dust bowl days of the 1930s Depression, the government has been working with
farmers to reduce erosion. Today, soil conservation is better. But fields still lose a lot of
topsoil because not all farmers use the best conservation methods. Dirt is washed away
by rain. That silt clogs up streams, rivers and lakes. But one region is trying to intercept
the silt before it gets to the river system. The GLRC’s Lester Graham reports:
Farm fields in all or part of 38 states drain into the Mississippi River. Some of the
tributaries of the Mississippi are so silted that dredges have to operate around the clock to keep river
shipping lanes open.
The Sangamon River in central Illinois is not big enough for shipping cargo, but it does
run into the man-made Decatur Lake. The city of Decatur gets its water from that lake
and often has to dredge it to keep the water inlets from clogging up.
Keith Alexander is the Director of Water Management for the city of Decatur, Illinois.
He says a little soil erosion on enough farms adds up:
“And the drainage area that runs into the lake is 925 square miles of some of the world’s
best topsoil. We have literally a half-a-million acres of corn and soybean fields that flow
into our lake that we use for drinking water purposes.”
Not only does the silt clog the lake, it also carries fertilizers and pesticides with it,
polluting the lake. The city has offered farmers financial incentives to reduce soil
erosion. But it hasn’t gotten enough participation from farmers to solve the problem. So,
the City of Decatur decided to try another approach. They would offer money to landowners to build ponds. Those ponds would be located in key drainage areas next
to farm fields.
Shannon Allen is a watershed specialist with the Macon County Soil and Water
Conservation District. He says it turned out to be a pretty popular program:
“The landowners wanted it for recreational purposes, obviously fish, maybe swimming
or whatever. We’re putting them in so we can collect sediment from the farm fields
above them so they don’t go into the river system.”
Shannon Allen says the ponds work a lot better at keeping silt out of creeks and rivers and lakes
than other methods to reduce erosion.
“Basically ponds collect 90% of the silt. And, so anytime you can put up a pond, you’re
doing better than a grassed waterway or a terrace that don’t reduce sediment loads by that
much.”
The city offers up to 5,000 dollars to landowners, but that’s well short of the actual cost. A typical pond
can cost 20 to 25,000 dollars to build. But landowners have been taking the city’s offer.
Alan Roberson owns a few acres at the bottom of a sloping corn field. About 42 acres
drains onto his property and then into a creek. He says when he moved there, there was
just a big ditch where stormwater from the neighboring farm fields washed a bigger and
bigger gully, carrying sediment to the creek:
“There was places eight, ten feet deep. We’ve lived here almost 20 years and it just kept
getting deeper as it went along. I hated to even come down here and look at it because it
was getting so bad. So, I’m glad that program came along to take care of it. As you can
see, it’s not doing that anymore.”
Roberson took advantage of the city’s pond program. Where the gully used to be, a carpet
of green lawn now borders a picturesque little pond.
Alan Roberson says the pond has a pipe in the bottom of it, kind of like a bathtub plug. It
was part of the design required to get the matching funds from the city. When the pond
fills up with silt, Roberson will be able to drain it and dig out the soil:
(Sound of water trickling)
“See this valve down here? You can actually pull that up. It could very well be 20 years
from now they’ll get enough silt in here where a person will have to bring it down. But
like I said, it’s designed to do that.”
That silt is some of the richest dirt in the corn belt and could be sold back to farmers or
used for gardens or flower beds. The landowner will have to pay the cost of digging it
out, but it’s that much more silt that won’t have to be dredged from the lakes or the rivers
that feed them, where people get their public water supply.
For the GLRC, this is Lester Graham.
