are there Water mocassins in Texas Colorado River? Yes.

I was reading that Water moccasins are extremely aggressive unlike Rattlesnakes which would rather not see or know humans at all. So, Water moccasins WILL attack people if they feel threatened rather than shy away from you like most other snakes except the King Cobra in India and a few others. But, all poisonous snakes if they feel cornered and unable to get away from you they will strike and sink their poison into people. The biggest problem in California is Diamond Back Rattler Babies that will not just give you a dose of poison but will because they are young and don't know any better fill people with all their venom instead that they have available. This can cause it's own problems for humans experiencing this too. 

I only had to kill one rattlesnake in my life which is 9 times more powerful venom than a Diamond Back Rattler. So, if you only get the anti-venom for a Diamondback at a hospital and have gotten hit with a Green Mojave Sidewinder then you will likely die. 

So, when I saw a green mojove going into an open door into a house where many family members and friends were I got my .22 9 shot revolver and shot it several times so it wouldn't bite any family or friends inside the house there in the desert. But, generally speaking I prefer to just step back from Rattlesnakes when I hear their rattles along dirt roads or trails throughout California. So, if you hear a rattle suddenly stop and listen where the sound is coming from and back away from the sound. However, often where there is one rattlesnake there are many in a breeding family so be careful of this too. If you stay more than 6 to 10 feet away from them they usually won't strike. They can strike at least 5 feet though, the bigger ones 6 to 10 feet long and a few inches wide. Look for the diamonds on their back. But there are also mountain rattlers in California too and they are usually brown colored.

I'm not familiar with Water Moccasins at all because they don't live in California. However, Diamondback rattlesnakes live in  many of the western States like California:

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Western diamondback rattlesnake

Snake

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Animal Fact Sheet: Western Diamondback Rattlesnake

Arizona-Sonora Desert Museum

https://www.desertmuseum.org › kids › long-fact-sheets

The Western diamondback rattlesnake (Crotalus atrox) is a heavy bodied snake with a triangular shaped head. There are two dark diagonal lines on each side of ...

 

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Water moccassins, diamond-backed water snakes, and blotched water snakes inhabit the river, while ashore copperheads, coral snakes, Texas rat snakes, eastern hognose, and eastern diamondback rattlesnakes may be encountered, so step carefully!Apr 21, 2012

Flora & Fauna of the Colorado River: Between Utley and ...

environmental-stewardship.org

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