Sediment/Water Quality

Accumulated sediment in Lake Manitou impacts recreational capacity, diminishes habitat, and can degrade water quality. 

The Lake Manitou Association has taken numerous steps over the past several years to preserve the water quality of our natural lake.  Lake Manitou is comprised of a watershed of nearly 28,000 acres southeast of Rochester and into Miami County, a very large area of runoff for our 775 acre lake (see watershed map here).  The two main inlets to Lake Manitou are Graham Ditch (east of Bessmore Park Rd bridge/White Creek) and Rain Creek (south end of lake past DNR wetlands).

Graham Ditch

Graham Ditch is one of our lake's filtering systems designed to control sediment and nutrient flow into Lake Manitou.  Located approximately 1/2 mile upstream from the White Creek bridge (next to the DNR ramp), this is a series of basins, earthen berms and a weir (or small dam), that is designed to capture sediment and chemical nutrients as rain water flows toward the lake.  Every few years these basins should be cleaned out as they fill up with silt quickly.  Thank you to our lake association members who measure these depths periodically and help determine sediment levels and the system's effectiveness.  LMA paid $5000 in November 2016 to excavate two ponds (from a depth of 12" to approximately 37") and added a new, large 24' x 527' trench basin to further capture solid material.  The downside of the current Graham Ditch system is it starts nearly 1/2 mile upstream; past this collection system, runoff and sediment enter the lake at the White Creek bridge.  The Graham Ditch system also is located on three separate private property owner's land- this is not on county or state owned real estate.  See the fascinating narrated video of this collection system below.

Sediment Dredging

In 2006, LMA was in the process of completing a dredging project at several sites when hydrilla was found in Lake Manitou, halting the dredging operation (want to learn more about hydrilla? click here).  After Indiana DNR declared hydrilla fully eradicated from Lake Manitou in 2016, the board has been actively investigating aquatic plant life restoration as well as continuation of the sediment removal project.  At this time, lots of fact finding is taking place to determine the best means of managing both sediment and nutrient balance.  Phosphorous and nitrogen are essential elements for plant life, but too much of them in water causes algae growth which depletes oxygen supplies.  Runoff from fertilized farm land contributes heavily to poor water quality by increasing nutrient levels beyond what is healthy for aquatic plant and wildlife (remember that rural 28,000 acre watershed?).  In addition to Graham Ditch, the majority of water flows through the south end of Lake Manitou via Rain Creek.  The board is actively investigating adding a similar sediment removal system to the south end of the lake as well as dredging other high priority sites that are prone to poor water depth and quality.  The Board has been given a $7500 grant from LARE (Lake and River Enhancement program) to do a study on the the best solutions for sediment collection/water quality enhancement for Manitou and also has received a permit from IN DNR for potential dredging at four seperate locations. The Board reached an agreement to dredge two of the sites in calendar year 2017-2018.  The inlet between channels 2-3 will be dredged mid August 2017.  Merrill Brothers of Howard County will perform mechanical dredging of the site with an excavator and containment barge.  Spoils and sediment will be trucked offsite and unloaded on a 2 acre parcel.  The nearly impassable channel will be widened to 35'x300' and a depth of 3.5'.  Work will take approximately 14 days.  The next permitted site to be dredged will be White Creek in front of the DNR boat launch.  As this is the inlet from Rain Creek, accumulated sediment continues to need removed from this area. Merrill Brothers have also been contracted to do this work and will mechanically excavate in late 2017 or Fall 2018.  They approximate 21 days to do this job.

It's imperative that we each treat our lake in a responsible manner! Lake Manitou is Fulton County's greatest asset and with your help we can preserve it for future generations.  A few easy ways to take personal responsibility are to:

  • Pick up your pet’s waste
  • Use phosphorous free fertilizer
  • Leave a buffer along the lake edge where you do not apply chemicals
  • Dispose of yard waste (leaves, grass clippings) properly- never blow them into the lake!
  • Properly dispose of any chemicals- not on the ground or in the lake
  • Install glacial stone along your concrete seawall- this reduces wave activity which helps prevent erosion
  • Avoid feeding the ducks, geese, and swans
  • Remove invasive species from your property
  • Don't use the lake as a bathtub- soaps, detergents, shampoos etc. are harmful to aquatic life
  • When operating your boat at high speeds, distance yourself away from the shoreline, islands, and shallow areas to avoid stirring up the lake bottom or causing harmful erosion

News & Events 12.5.18

Annual LMA Dues

Annual LMA Membership Dues should be paid by the end of January. Click HERE to process your donation now. 


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