So I know that Walleye are only officially in a few lakes in Texas, but I swear I saw one the other day in Medina lake. It was maybe 13-15 inches, thin with a big dorsal fin, and I think tan colored. Anyways, I've seen enough walleye to recognize them. I think they were planted there decades ago, but I did find a website that lists them as one of the species in the lake https://outdoorsman.guide/medina-lake-fishing-guide-texas/ . Of course fishing websites are often very inaccurate, but just curious if anyone thinks they could still be in there undetected?

I know they were stocked many years ago, but I would say if you saw one, and are familiar with what they look like then the answer is probably yes, that there are still some in the lake.

Is there anything upstream where a walleye could come from?
I have a tough time believing that one would be there from the original stockings of walleye way back. Especially have that drought. Back in 06?

No..

Is it possible you saw a gaspergou? They have the same dorsal configuration, however they are thicker and one solid color (greyish).

Probably a Plecostomus…aka sucker fish.

There would be at least some regular reported catches of walleye at Medina, if they were still there.

There have been rare reported catches of rainbow trout in the UPPER Guadalupe River, most likely explanation is from private Upstream stocked ponds running over during large rain storms.

And then there was this report several years back,

https://www.expressnews.com/news/lo...tor-on-upper-Guadalupe-River-7392808.php

First a shark and now a walleye....I’m going to go with a white bass, although not tan, they actually exist there unlike a few other things mentioned here.

The last stocking was in 1974, but they can live to be 29 years old. I wouldn't doubt they've spawned a few times and there are some left in there!

With the lake dropping as low has it has in the past and nobody has caught one in over 30 years, it’s doubtful.

Here you go Carl........
https://outdoorsman.guide/medina-lake-fishing-guide-texas/

As you are out and about and run across a GW or biologist at the lake present them with that question.
He'll either know, or shrug his shoulders and look at you like you've lost your mind!

I believe the Medina River feeds Medina Lake and not Guadalupe.
I could be wrong but I'm pretty sure that TPWD does trout stockings at the Bandera City Park, which is a dammed up portion of the Medina River. And that isn't to far upstream from Medina Lake. So I could see some trout making their way down to Medina Lake, especially if Bandera has some incoming water to pick up flow over that low dam they have.

The Medina River feeds Medina Lake. You are correct.

Nothing was written in the post above, about the Guadalupe River feeding Medina Lake, it is common knowledge that the guad feeds Canyon Lake.

The second paragraph was about separate unusual cases involving rainbow trout and other strange observations with no mention of Medina. Both Canyon and Medina were regularly stocked with walleye many years ago, and walleye were common catches at those times- doesn't necessarily indicate they were self-sustaining at that time or now. Seeing or catching a single rainbow or walleye in the respective Rivers or lakes does not necessarily mean that a sustaining population of either rainbow or walleye exists at either Lake- there might be other explanations.. Sorry for the confusion, the complicated post was made in a hurry, and I can see how it might be interpreted in different ways.

Here's a link to another similar question on another forum, 2nd entry:

http://www.texaskayakfisherman.com/...amp;sid=8fe51c367ca9e31d03ff53cb71bbfa19

Hope this helps.

There is this whole thread on walleye in Medina, but then you throw in the comment about catching trout in the upper Guadalupe.
So I thought you were thinking the Guad fed Medina. Sorry, I didn't realize that it was just a random irrelevant comment that had nothing to do with the conversation.