There must be something in the water
Oh, there must be something in the water (amazing grace). – Carrie Underwood
There is definitely something in the water, but with apologies to Ms. Underwood, I’m not sure it’s amazing grace.
This time of year, with rains heavy and the Sangamon River fluctuating up and down by 5 and 6 feet at a time, there is definitely something in the water. I can see it, and it’s mostly dirt.
It is told that in days of yore, when this area consisted nearly entirely of prairie grasslands, water could take several months to percolate from these grasslands down into prairie rivers such as the Sangamon. This meant, as the tale goes, that flooding was a fairly rare and rather inconsequential occurrence.
Now within a few hours of a heavy rain, the Sangamon, measured at the Fisher Gage, can quickly rise 5 or 6 feet, sending meteorologists running to the tube and to their websites to issue immediate and dire “flash flood warnings.” And of course, along with all this water comes the dirt.
Our Sangamon is measurably not a polluted river.
Based on the Upper Sangamon River Conservancy’s regular testing of species that reside in the river, both “macroinvertebrates” (small bugs) and its well-documented healthy and diverse freshwater mussel populations, the waters of the Sangamon in the Champaign County area are in excellent health.
We should all take great pride in this fact that surprises many, but not me.
In the depths of winter, as the ground freezes and precipitation falls as snow that sometimes spends weeks just sitting there quietly atop frozen fields, the Sangamon rarely floods. And the waters of the Sangamon flow relatively shallow and surprisingly clear with sometimes over 6 feet of visibility. It’s so clear that the river’s bottom details are clearly visible from the top.
Not so in midsummer.
Now the Sangamon flows thick, rich, opaque and brown with “suspended solids”, also known as dirt. This dirt comes from two sources: bank erosion on the Sangamon (and its tributaries) and runoff from agricultural fields.
So is there a problem with all this dirt?
It’s a very real problem for farming operations. Once topsoil leaves an agricultural field, it never returns.
Of course, when rainwater runs off a field and flows downriver it can return again in the next rain. But when water evaporates up into the clouds, it takes the H2O and leaves the dirt behind.
In our area, this dirt flows downriver only to be deposited hither and yon in various floodplains, such as my backyard. So the floodwater recedes and leaves behind at least an inch of solid black muck where my grass once was. Presumably, this muck was quite recently just innocently laying around enjoying the sun minding its own business on somebody’s farm field. Then the rains came and washed it across the land, down into a “ditch” into the Sangamon and on downriver to my place.
Much of the Sangamon’s dirt falls out when the river hits Lake Decatur in Decatur, where the dam, constructed in 1922, acts like a giant sink trap. Dirt drops to the lake bottom as the river slows to near imperceptibility in the deep and wide lake, while the relatively clearer water on top flows over the dam and on downriver.
Decatur must now embark on a multi-million dollar project (at taxpayer expense) to dredge this collective dirt from upstream farm fields and bank erosion from the bottom of Lake Decatur. This is because the lake bottom continually rises as the lake’s surface, limited by the height of the dam, has remained basically at the same level since 1922.
This has the obvious effect of reducing the water storage capacity of the lake itself, which could be a problem when that lake provides your drinking water.
A seemingly obvious solution would be to simply mimic the water cycle by hauling off the dredged dirt from the bottom of the lake and distributing it among anxiously waiting upriver farmers who would happily return it to the fields from whence it came.
The problem is, being in the water and then sitting at the bottom of Lake Decatur strips this dirt of any and all of that useful organic matter important for growing things and turns it into a lightweight, silty, nearly valueless ash-like substance.
Decatur is therefore just going to pile it up somewhere nearby and scratch their collective heads about what to do with this worthless pile of silt, which was, not so long before, some of the most valuable topsoil on the planet.
None of this is to accuse, place blame, cry wolf, whine, cry foul, or anything else. Nothing I’ve written here is news to anyone in the water business or in the agricultural industry. Here’s hoping it’s of some interest to you (since you made it this far).
And here’s hoping it can help raise awareness of the system we’ve all created and its environmental consequences, particularly what’s in the water.
In the end, I suppose it’s possible that there may actually be a little amazing grace to be found there, but most of it is just plain dirt.
Appeared as Notes from the River, Mahomet Citizen by Scott Hays, July 16, 2015