What about Sediment?

Pucker Street Puddin'.

One of the concerns regarding dam removal is that the years of accumulated silt and debris at the upper base portion of the dam will come crashing down into the river, making horrible mud slides of everything downstream "for years and years".  Make no mistake, the river will want to cleanse itself. Why don't we consider allowing it to this time around?

**(inserted 2/19)  Here's how one expert at the DNR OPINED how he might handle sediment  if the dam is removed. Not the offical strategy; as it isn't an official project yet:

"The process of dam removal can help manage the sediment for the long-term life of the river. To deal with accumulations over the years, The DNR would install a sheet pile dam above the existing dam, which would have stop logs that could be pulled to control the draw down. Perhaps drawing it down at one foot per week.  They would also  maintain a sand trap to remove sediment as it came down." --  J.Wesley, MDNR

Consider this analogy for a moment:  When a pipe is clogged in your sink, and you wish to cleanse it, you must flush out the offending material. Rivers that are un-dammed do this naturally and constantly. Dammed rivers do not, and are robbed of this dynamic. The photo above shows what a great job human engineering does trying to duplicate a free-flowing river. We conclude that its a little cheaper to let it happen naturally.

FACT:  The Dowagiac is supposed to move between 1 and 5 tons of silt per day.

FACT:  Withholding sediment from depositing naturally will remove riffles, create sediment starved water, and accelerate erosion in downstream portions of the river; grinding away at them much faster than the banks can sustain.  You see, 'too much' sediment is bad for the water above a dam, and TOO LITTLE creates serious erosion problems below the dam.

Don't believe us?    GOOD !  Please refer to pp. 8 and 9 of:

THIS CASE STUDY ON SEDIMENT TRANSPORT.

If the dam is removed, ---starting immediately, there will be a scary looking plume of silty thick water coming down. However, with a head-start and  the above management technique,  the previous sediment removal  won't be anywhere near as bad as it could have been. Why?

The Dowagiac has a major benefit in reducing this components effect, unlike other dams.

The dam was "drawn down" in 1999.  This process allowed a large portion of that collected sediment (not all of it) to rinse its way downstream. The remainder was removed over a period of weeks at cost to the city. When all were agreed that the sediment removal should stop, it was after $50,000 and 14 cleanings by various contractors. Here are the spoils from 1 cleaning to give some perspective.

 Here is just 30 days worth of Pucker Street Sediment after the previous cleaning of the trap.

Don't kid yourself. The sediment will keep coming, even if the dam comes back on-line, all shiny and new. It will damage the dam turbines and affect water quality, and arsenic makes wading the river  kind of a bummer.  Potential dam buyers may not realize the heavy sediment load that makes this river unique among others that have been dammed. Farmers will keep farming, and runoff will keep running.

In less than 3 years after this cleaning operation,  river-users and residents reported that the new, flushed sediment was almost completely gone from the riverbed below this mess.Imagine that.

A level of arsenic in this dam sediment was discovered, and readings were taken that were beyond established tolerances. Arsenic is commonly found in runoff sediment as a by-product of agricultural and farming chemicals.  It is also used in potato farming. Apple orchards with cores, stems, and seeds, all organic--have arsenic in them.  

Natural river flows allow these trace amounts to leave and dissolve in a normal, safe pace.  Dams allow these particulates to gather and collect in a condensed area, making them a conscern.  Those levels of arsenic will likely not occur in the current environment----IF the river is free to flush and distribute those particles naturally, rather than let them concentrate and collect. If a dam operation resumes, and impounding happens; the sediment game will begin all over again.

Remember the reason for the silt and sediment accumulation and resulting arsenic? Its there because a dam was erected to hold it back.

Looking Ahead:

If development increases, as any Mayor would hope to see, rainwater will have  less ground to absorb rain, and more concrete, streets, roofs, and parking lots  rapidly push water somewhere.  If agriculture practices remain the same, the rich, fortified and expensive topsoil , complete with pesticide, fungicide, and fertilizer, will seep down the fields with heavy spring and summer storms, right into the rivers edge. That edge today? is partially stabilized by green strips along the banks to naturally prevent this. However, the topography of the area,  if viewed on mapquest, will show you the depressed veins of land that lead right to the river. Several farmers in Niles Township understand how leaving a 'buffer zone' between their crop and the riverbank helps keep their soil on their land, and prevents excessive river sedimentation.We applaud them. They get to keep thier rich soil on their land, and help the river in the process. For those that dont, they will turn and till their soil, and it will continue to depress lower on their acreage, leaving a horrible mess of ponds when rains come.

Final Conclusion and FACT:

DID YOU KNOW:    There is a FREE, 24 x 7x 365 sediment-moving system available that doesn't need permits or heavy equipment or authorization from government agencies to conduct these systemic operations. Plus, unlike work-crews, it especially works best during heavy rains--and never requires a break.

If any of this was valuable; please pass this site along to Niles Residents or concerned citizens so they can learn more.

Thanks!

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