Hello, the primary seal appears fine to me.

I have pulled the trim panel while cursing GM engineers up one side and down the other; even with a GM service manual that was a job; mainly with trying to figure how to unhook the control switches and I would like to know who put that screw where you can not remove it without special tool RX-J-KY-23 (joke) because I would like to give them a hard kick in the seat of their pants.

The splash shield appears to be firmly attached all around with no holes except the ones made on purpose by GM. What is the next likely area of such a serious leak that I will get a puddle of water if I get an all day hard rain?

Pulling the carpet back the under pad was soaked with water; so yes, getting the carpet out would be a smart thing to do but by myself I probably won't attempt it. It sucks not having an helper.

Now that you have the door trim panel off, have someone direct a stream of water to the outside of the door and you observe how the water is being channelled through the door and out to the road (or into the car). The adhesion to the water shield might look good, but could still be an issue. If the drain holes at the bottom are plugged the water will backup into the door and into the car.

Use the forum'* search feature for "water leaks" and you will see numerous threads on this, and how other people corrected their leaks.

I just did a search for water leaks in the little search bar at the top and got a huge list of unrelated posts.

No helper as I said before but I will shut the door and spray the car with water to see if I can detect if the leak is from the door. The plastic shield was firmly attached but perhaps water is still getting past it somehow. Will report back.

OK, I sprayed the water as if it was a torrential downpour on a summer day twice. The first time I did not really see anything but the second time I did; I left the driver side door closed and did my inspection from the passenger side. I noticed two small streams of water coming down from the firewall; one over at the very most left side and the other where the steering column exits the car. So where are the possible areas those leaks could originate from?

Maybe try to get the hose to stay in place on the roof somehow, and try to get the water only flowing over one door, then maybe hop in the other side and see if you can find any leaks.
It may be coming in around the cowl under the wipers, I think I heard somebody say drains for it can clog and somehow let water in, not totally sure though, maybe somebody else knows what other spots could leak.

EDIT, just noticed your last post, I typed this one out before I seen it.
Definitely thinking maybe the cowl under the wipers somehow, wish I could be of more help.

It is getting late so I am stopping this project for the evening. I will pick it up tomorrow and let everyone know what I find. Thanks everyone for the help.

Well, got called into work so I will not be able to work on this tomorrow; I will check back in Friday.

Going through search results is like dating ... you have to go through a lot of wrong ones before the right one pops up. Unless you are Mike, in which case the first one to come along will have to do.

Search for "cowl water leaks".

The quick search is probably doing an OR search so if you type water leak, it will return results with water and return results with leak; so a fuel leak will be in the results as well as oil leaks. The quick search should default to an AND search so that the query returns a better results list in which only posts with water and leak are return; this will then exclude oil leaks and fuel leaks which were irrelevant returns.

I was not able to get a lot done today. It has been a rainy day here and I had to work between the rain showers. The old girl is sitting outside the shed because the tractor is in there waiting for an oil pan gasket. It is an 8N Ford with a cast iron pan that weighs about 23kg/50lbs and the front of the tractor has to be swung out of the way as well. However, that is a different story for a different forum .

I had a time getting the wiper arms off; I actually thought they were stuck but found out the tabs were bent and thus not doing the proper job of releasing the tension. After a couple of hours of trying; once I bent the tabs back into position they just slipped off. I think it is likely the leak is around the air intake, the drain hole for the water is open. It is possible the seal has shrunk around the air intake. I can not really believe GM would make the air vent in this manner, a hole with the vent pushed through it, when this style has known to be problematic for leaking in other cars.

There is also a water shield over the vent and it is possible water is getting by that as well, I removed it and will make sure I have a good seal underneath it.