Turbidity in Western Lake Erie: Satellite images

[Dave Kelch, Sea Grant Extension Specialist]

With the recent discussion topics regarding turbidity and phosphorous in Lake Erie, I thought these recent images taken April 2, 2008 from the  NASA Moderate Resolution Imaging Spectroradiometer (MODIS) TERRA satellite would be interesting.  Not the turbidity from the Maumee River and Sandusky Bay.
http://www.sagady.com/turbidity/WestLkErieandLkStClair04022008.jpg
http://www.sagady.com/turbidity/LakeStClair04022008.jpg

This gives one an idea of how much turbidity and associated phosphorous load enters the lake from just these two sources.  Not that the flow from the Detroit River is not very bad, although Lake St. Clair is very turbid at the east side.

Dave Kelch, Sea Grant Extension Specialist, Ohio Sea Grant

[Buckeye]

Dave do you know what the difference in watershed area is between the main western basin tributaries (Maumee, Sandusky, Toussaint, and Portage) and the main eastern tributaries of Lake St. Clair?  The only 2 I can think of for Lake St. Clair are the Thames and the Sydenham.  I know from having been on ag tours of SW Ontario, there doesn't seem to be much of an effort to buffer the ditch and stream banks along crop fields.  In many cases, I've seen some tillage practices, like working fields almost to the ditch bottoms, on really unstable light sand and loamy soils.  It makes me cringe to think how much silt and accompanying nutrient load would end up in Lake St. Clair after a major rain event.  A silt plume usually shows up after a big rain on the satellite maps on the east side of St. Clair and the Detroit river.   

[Dave Kelch, Sea Grant Extension Specialist]

Buckeye:

The following information comes from: http://www.maumeerap.org/9-draft-HUC-Maumee12-21-05.pdf,  The Maumee River Watershed, Ohio EPA:

[i]The Maumee River is the largest Great Lakes tributary, draining all or part of 17 Ohio counties, two
Michigan counties, and five Indiana counties. The total river basin covers 8,316 square miles. The
mainstem of the Maumee River is approximately 130 miles in total length with 105 miles in Ohio.
Only the lower 22.8 miles of the Maumee River is included in the Maumee AOC, therefore only this
lower portion is addressed by the Stage 2 Watershed Plan.
The river drains about 6,586 square miles, of which about 85 percent is agricultural. Daily average discharge ranges from a high of 94,000 cubic feet per second (cfs) to a low of 32
cfs, and contributes about 25 percent of the total tributary discharge into Lake Erie, exclusive of the Detroit River. The average annual rainfall on the river basin is 34.5 inches.1[/i]

The website above will give you more information than you probably want to know about the Maumee River and drainage basin, along with a number of excellent maps.

The following website gives you drainage information on the US side of Lake St. Clair, which is primarily residential and city (Detroit area): http://cfpub.epa.gov/surf/huc.cfm?huc_code=04090002  Not much agricultural run-off from the US side, yet the Canadian side is much different, and the map on the website in my previous message shows.

The following was taken from: http://www.great-lakes.net/lakes/stclairReport/summary_00.pdf
A Lake St. Clair Conference report:

On the Canadian side, agricultural land use adversely affects the lake, particularly the nearshore
environments, via drainage from the agricultural fields. See Figure 2 (Infrared Image of Lake St. Clair). This image shows that farm fields in western Ontario, which border Lake St. Clair, are being intensively cultivated for the production of corn, tobacco, tomatoes and other crops. Some of the land near the St. Clair River delta has been drained for crop land, and pumping stations are needed to de-water the fields. During rain events, suspended sediments, farm fertilizers, and herbicides drain into the lake per the Syndenham River and Thames River. Agricultural drainage in the Thames River is important in that this stream was formerly a most important Walleye spawning stream. In addition, a large area of dense submersed aquatic plant growth occurs south of the Canadian side of the delta, and this growth area may reflect the nutrient loading from the nearby agricultural fields in Ontario.

Regarding the size of the drainage from Canadian portion of the Lake St. Clair, Canada contributes approximately 77% of the drainage to the lake.  The following drainage information came from:  http://www.bkejwanong.com/StClairMgmt/Draft%20Report/Basin_3.pdf, The Lake St. Clair Canadian Watershed Draft Technical Report: An examination of current conditions:

The watershed area for the Canadian tributaries draining into Lake St. Clair is
approximately 10,000 km2 (1,000,000 hectares). The two largest tributaries are the
Thames River (582,700 ha) and the Sydenham River (272,400 ha). The Thames River
discharges into the southeast corner of the lake and the Sydenham River discharges into
the Chenal Ecarte. Along the eastern shore, Rankin Creek and several agricultural drains
discharge from a small triangle of land located between the Thames and Sydenham
Rivers. Along the south shore, the Ruscom, Belle and Puce Rivers, together with small
creeks, drain approximately 66,000 ha of Essex County north to the lake.

These hectares convert to the following square miles:
Thames: 2250 square miles
Sydenham:  1052 square miles
Total drainage for both: 3302 square miles

Compared to the Maumee drainage:  6586 square miles, again making it the largest tributary to the Great Lakes.
Both images in the previous message can attest to the amount of turbidity which both drainage system contribute, yet the siltation from the Thames and Sydenham most likely remains in LakeSt. Clair; again, in the previous message images, note the flow from the Detroit River reveals minimal turbidity.

Hope this answers your questions.

Dave Kelch, Sea Grant Extension Specialist, Ohio Sea Grant