Q.Johnson grass
I have Johnson grass growing in a water front yard near the edge of the lake. What is the best method to get rid of it? I am concerned about using herbicides that close to the water.

You may want to check with your County Extension Office to find out the safest way to treat and remove this grass near a water source.
Here are some links to help you.
https://www.gardeningknowhow.com/extension-search/
https://www.gardeningknowhow.com/plant-problems/weeds/controlling-johnson-grass.htm