Here is a Notice to Mariners from the Army CoE regarding the southern-most Lock and dam  on the Mississippi system:

SPECIAL NOTICE TO NAVIGATION INTERESTS
Locks 27, Upper Mississippi River Mile 185.5

1. All navigation interests are advised that both the Main and Auxiliary Lock Chambers at Locks 27 in Granite City, IL will be closed until further notice effective at 1600 today. Last night the downstream protection cell developed a breech in the interlocking sheet piles and began to spill the rock fill into the approach area of the 1200-foot main lock. While the spilled rock remains an obstruction to the approach to the main lock, our engineers have determined that the cell is not stable enough for tows to touch or even for wave action caused by any water craft. Crews are in the process now of removing the remaining rock from the cell. We hope to have a better estimate of closure duration by morning.
2. All navigation interests should be alert for, and abide by, any special instructions that may be issued by the Lockmaster during this closure.
   FOR THE DISTRICT ENGINEER:
   //S//
   Andrew C. Schimpf, P.E.
   Rivers Project Manager

This is the lock pleasure craft boaters call "Chain of Rocks."  I've actually never heard it called "Lock 27" in the pleasure community, but that's apparently what the project managers and commercial folks call it, and that is how it identified on the chart.  The lock is at the south end of a wide, commercial canal that's several miles long.  This closure will affect everyone north of the lock.  You have to go through here; it's not only the critical path, it's the only path.

This would be a nasty place to get hung up.  There are no stops in this section of the river.  This area is just north of St. Louis, between the marinas at Alton/Grafton/St. Joseph and Hoppies Marina at Kimmswick.  Mississippi River current in this area would tax the capabilities on many trawlers and slow cruisers, so returning north to the cover of marinas would be difficult.  When the Lock does open back up, I would guess commercial traffic will have priority.  Be aware, and plan accordingly!

Jim

Peg and Jim Healy aboard Sanctuary
Currently at Rock Creek, Pasadena, MD
Monk 36 Hull #132
MMSI #367042570
AGLCA #3767
MTOA #3436

Even on a good day, you can have waits at this lock. When we were through
there last week, there was a lot of tug/tow traffic. The canal will pile up
with tows who bank their barges so the downstream running tows can get
through. Then they start out into the canal again.  Be SURE you do not pass
the stern of one of these tugs !!! Coordinate all movement with the tugs
ahead of you.
Good place to stop is Port Charles Marina if you are coming down the
Illinois River. Its MM 221.5, cheapest fuel and free loaner car, $1/ft.
Many boaters will choose to sit at Alton because its closer to this lock but
I would expect them to fill up.
R,

-----Original Message-----
From: great-loop-bounces@lists.trawlering.com
[mailto:great-loop-bounces@lists.trawlering.com] On Behalf Of Jim Healy
Sent: Tuesday, September 18, 2012 7:39 AM
To: great-loop@lists.trawlering.com
Subject: GL: EMERGENCY CLOSURE - CHAIN OF ROCKS LOCK, MISSISSIPPI RIVER

Here is a Notice to Mariners from the Army CoE regarding the southern-most
Lock and dam  on the Mississippi system:

SPECIAL NOTICE TO NAVIGATION INTERESTS
Locks 27, Upper Mississippi River Mile 185.5 1. All navigation interests are
advised that both the Main and Auxiliary Lock Chambers at Locks 27 in
Granite City, IL will be closed until further notice effective at 1600
today. Last night the downstream protection cell developed a breech in the
interlocking sheet piles and began to spill the rock fill into the approach
area of the 1200-foot main lock. While the spilled rock remains an
obstruction to the approach to the main lock, our engineers have determined
that the cell is not stable enough for tows to touch or even for wave action
caused by any water craft. Crews are in the process now of removing the
remaining rock from the cell. We hope to have a better estimate of closure
duration by morning.
2. All navigation interests should be alert for, and abide by, any special
instructions that may be issued by the Lockmaster during this closure.
FOR THE DISTRICT ENGINEER:
//S//
Andrew C. Schimpf, P.E.
Rivers Project Manager

This is the lock pleasure craft boaters call "Chain of Rocks."  I've
actually never heard it called "Lock 27" in the pleasure community, but
that's apparently what the project managers and commercial folks call it,
and that is how it identified on the chart.  The lock is at the south end of
a wide, commercial canal that's several miles long.  This closure will
affect everyone north of the lock.  You have to go through here; it's not
only the critical path, it's the only path.

This would be a nasty place to get hung up.  There are no stops in this
section of the river.  This area is just north of St. Louis, between the
marinas at Alton/Grafton/St. Joseph and Hoppies Marina at Kimmswick.
Mississippi River current in this area would tax the capabilities on many
trawlers and slow cruisers, so returning north to the cover of marinas would
be difficult.  When the Lock does open back up, I would guess commercial
traffic will have priority.  Be aware, and plan accordingly!

Jim

Peg and Jim Healy aboard Sanctuary
Currently at Rock Creek, Pasadena, MD
Monk 36 Hull #132
MMSI #367042570
AGLCA #3767
MTOA #3436

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Clarification - My reply below might be misleading.
Port Charles Marina is MM 221.5 on the Miss River. After the Illinois joins
the Miss River its just a few miles upstream. We were there 2 nights and
really enjoyed it. Took the car to Walmart, grocery shopping, etc.
R.

-----Original Message-----
From: great-loop-bounces@lists.trawlering.com
[mailto:great-loop-bounces@lists.trawlering.com] On Behalf Of Ralph Yost
Sent: Tuesday, September 18, 2012 8:20 AM
To: 'Jim Healy'; great-loop@lists.trawlering.com
Subject: Re: GL: EMERGENCY CLOSURE - CHAIN OF ROCKS LOCK, MISSISSIPPI RIVER

Even on a good day, you can have waits at this lock. When we were through
there last week, there was a lot of tug/tow traffic. The canal will pile up
with tows who bank their barges so the downstream running tows can get
through. Then they start out into the canal again.  Be SURE you do not pass
the stern of one of these tugs !!! Coordinate all movement with the tugs
ahead of you.
Good place to stop is Port Charles Marina if you are coming down the
Illinois River. Its MM 221.5, cheapest fuel and free loaner car, $1/ft.
Many boaters will choose to sit at Alton because its closer to this lock but
I would expect them to fill up.
R,