After many hours of research I came up with this map showing the state line.
I overlayed it on a GoogleEarth image here.

Interesting, the yellow line I added from the observation tower to the end
of the lock wall intersects the channel at the state line. So anything
cruising the channel edge upstream would be in Mo.  Be nice if they added a
marker at that intersection.  It also looks like the distance from the
spillway to the intersection is about 2 1/3 "rock jetty lengths".

I also heard this story. See the Alton Corp Bdy line? Looks like they got
that area in the city so all construction was under one set, their rules?
Different Unions, etc. in Mo. would have made construction rough on the one

Al Smith
Bridgeton, St. Louis County  (admin)

On Sun, 20 Feb 2011 22:09:08 -0600, David Marjamaa <[log in to unmask]> wrote:

>I received a notice from the e-Bird verifier that the White-winged Scoter
>should be an Illinois bird.  I have read similar things in the past for
>other birder's reports dealing with the Melvin Price Dam.  I am a retired
>Air Force Navigator and a professional MLS librarian, and understand maps.
> All of the maps I have dealing with the Missouri / Illinois state line show
>the state line running down the middle of the river, and the middle of the
>dam. "Google Maps" and the "Missouri Conservation Atlas" reflect the middle
>of the river and the middle of the dam as the dividing line (even my AAA
>road maps reflect the middle of the river as the dividing line).  If I plot
>the position of this bird on e-Bird maps, it shows St Charles County,
>Missouri.  Please inform me what maps we are using to make 10 feet northeast
>of the rip-rap wall to be in Illinois.
>I understand changes in river course to create different state or county
>lines, i.e., Kaskaskia Island is in Randolph County Illinois, but physically
>on the Missouri side.  Or, Howell Island is St Charles County, but sits
>pretty much on the St. Louis County side.
>Will an expert please educate me about where the state line falls in this
>situation, and inform me what reference map is used.
>Thank you sincerely,
>   David & Mary Anne Marjamaa
>   Manchester, MO
>The Audubon Society of Missouri's Wild Bird Discussion Forum
>ASM Website:

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