Mosquitoes breed in stagnant water, so you'd be wasting your money putting anything into flowing water. (I live on Sycamore Creek in Fort Worth and have had the same discussion with neighbors).
Your issues probably stem from stagnant water collected in trash along the creek or overflow areas left behind after high water. If you'll visit the Library page of the Dirt Doctor site under M (
https://www.dirtdoctor.com/dirtdoctor-library?letter=M) you'll find a number of solutions suggested regarding mosquitoes. And if you're around on Sunday morning, this would be an excellent question to call into the radio show - every year Howard talks about the problems of the ineffective municipal spraying programs aimed at mosquitoes that miss most of them and kill beneficial insects.
866-444-3478, 8 - 11am, Sunday mornings, Central time (
Radio broadcast information).