Getting the lead out of Big R.

[Al Agnew]

Back in April, I floated Big River from Desloge to St. Francois Park. Just a short distance below the mouth of Flat River Creek, I came upon several workers with heavy equipment, and then what looked like a low dam, constructed of limestone boulders, that stretched across the river. It was just high enough to raise the water level just above it about 18 inches at the water level the river was that day (about normal for springtime), and it looked barely floatable, but the weather was cool, the water still rather cold, and I didn't think it was prudent to try it. I was more than a little aggravated about it, though, because I'd just hurt my achilles tendon the night before, and didn't look forward to dragging the canoe around it. Fortunately, a couple of the workers came down and helped me carry the canoe the 50 yards or so it took to get past it. One of them told me that the structure "should make your fishing better".

This was the first I had encountered such a thing, and had heard nothing about any program. I assumed it had something to do with removing lead-filled mine waste from the river, though I couldn't really see exactly how it would work. Would the sediments settle above the "dam", and then be excavated periodically?

I left soon afterwards for Montana and kinda forgot about it, until it came back to me as I was thinking about the gravelling in of the streams in my recent thread. So I emailed the biologists at MDC to try to get the story on it.

It turns out that MDC had nothing to do with it. It is a feasibility study of the EPA and Corps of Engineers in conjunction with the Superfund sites in the old lead mining district. The structure is called a "Newberry Riffle". When it was first constructed a month or more earlier, it consisted of a stairstep riffle, with the highest step being the farthest upstream, a trough between it and the next step, which was lower, another trough, another lower step, one more trough, one more lower step. The theory is that the sediments would settle in each trough, and be excavated periodically, instead of the upstream area being excavated. When first built, the steps, which bowed slightly downstream in the middle, were about of even height all the way across the channel, but the plan was that the center portions would settle somewhat deeper, and make enough of a chute that it would be floatable at normal water levels.

Well, I don't have much confidence it will work as planned. For one thing, the chute didn't materialize, the center portions didn't sink. Worse, the big flood that came back in early April rearranged the rocks until there were not well-defined steps, just a sloping jumble of rocks as far as I could tell. And I can't imagine that future floods wouldn't do the same thing, making sediment trapping unlikely and excavating impossible. Plus, it seems to me that a whole lot of these things would be needed covering the 20 or so miles of river that are most bady affected. Are there enough landowners willing to give the Corps access to the river? And it seems to me that with the amount of mine waste in the river, you'd need to keep these things up and keep excavating for a LONG time.

One of the MDC biologists told me years ago that they were continually trying to figure out how they could get the lead mine waste out of the river. One of their ideas was to find various old channels and side channels, divert the river into them, dig out the previous channels as much as possible, and the re-divert the river back into them. That would be a huge job in itself, but would seem to be a little more likely to actually work.

[Quillback]

Interesting. You would think that they would have planned on floods, but maybe this is experimental and will go down as a lesson learned. My guess is that there is not enough money in the budget to do a big solution such as diverting the river and then cleaning out the river bed.

[Daryk Campbell Sr]

I tip my hat to them. I really don't know IF it will work, but if no one ever tries.... All to often we like to complain that nothing is ever being done, they have tried something, maybe it needs to be tweaked. I say keep trying.

[mjk86]

This is weird. I understand that there is a ton of lead there, but since its so heavy it seems like it would require a huge flood to really move much lead containing sediments at all? Maybe there is more in the actual water column than expected. Maybe since that stretch of river is so messed up already its good to experiment on. That was the stretch of river that I grew up fishing more than any other place combined. Its not the best but special to me. Hmmm.....now that I think about it maybe all the time spent taking lead baths in that river explains alot. Ha!

[Quillback]

Interesting quick read on lead mining in SE MO. I didn't realize that it had been started back in the 1700's by the French.

https://en.wikipedia.org/wiki/Southeast_Missouri_Lead_District

[moguy1973]

I'm guessing this would be like how a gold sluice box works? The heavy stuff sinks at the dam and the light stuff flows over. Then they can retrieve the heavy stuff at their convenience?

[Al Agnew]

The lead, and other heavy metals such as cadmium and zinc, is in trace amounts in the mine waste. The lead was mined by removing large amounts of rock containing the ore, crushing it, and removing the ore. The crushed rock left behind was piled up in large "chat dumps" up to 300 feet high and spread out over a large area, and the silt left behind from washing the crushed rock was impounded behind dams. Erosion of the chat piles and the flats of silt, and failure of some of the dams, allowed this waste to get into the river. It is very weakly soluble in water, which means that the heavy metals are very slowly but continually being leached into the water itself from both the chat and the silt that settled to the bottom. The chat itself consists of fine dolomitic limestone particles (mostly sand sized grains to grains about a quarter inch in diameter). There isn't enough heavy metal in these to make much a difference in how heavy they are compared to chert gravel of the same size. We're not talking about grains of lead like gold dust here, we're talking about very fine gravel and sand that has tiny bits of heavy metals within each grain. So the sluice box thing wouldn't seem to work.

So I'm still not sure of what they hope to accomplish with the Newberry Riffle idea.

There are two very different problems with the mine waste. One is the leaching of the heavy metals from it into the water. If the heavy metals were completely inert in the waste, that wouldn't be a problem, since nobody eats gravel. But they are not, so organisms within the water take in minute amounts of heavy metals, which get passed up the food chain (and into humans who eat the fish). The heavy metal contamination of the water comes not only from the mine waste in the river itself, but from water running over and through the chat piles and silt impoundments. The Superfund clean-up has covered up most of the mine waste on the land (Except for the vast amounts of silt in St. Joe State Park, which is still quite unbelievable that the lead company was able to foist that albatross onto the state of Missouri, and that everybody seems to think it's perfectly fine to bill it as this terrific place to ride ATVs through all of it and breathe in the dust constantly. Oh well, it keeps them off of more fragile places, I guess.)

The other problem is simply the physical properties of the mine waste...the fine sand and gravel is very sterile in itself, and it fills in pools, fills in the crevices within the rocks and gravel where bottom organisms grow, and makes the stream habitat and fertility far worse than a normal stream.

The only way to fix either problem is to somehow excavate much of the waste from the river channel.