If rye is really what you have, you can use a product called revolver to help you transition back to bermuda. It is used during the spring transition by professionals to get the cool season turf to die off when the bermuda starts coming back. It is not, however, labeled for us over the top of st augustine. Don't give away trade secrets :>) I don't know about CO, but in TX only licensed professional can use Revolver. Otherwise homeowners have to use granular atrazene formulated for Saint Augustine lawns to do the trick.

The annual rye should die out by itself. That's why they call it annual. Tall fescue will have to be pulled. It should come out in clumps. Knock the soil off the root system back into the hole and the St Aug will spread back in to fill. What do you mean, variegated? To me that word refers to a leaf that is both green and yellow or white along the margin or in streaks or spots.

Kurchian, The advice from your local nursery was to plant Annual rye grass with some wildflower seed. The annual rye seed would only grow this year and would not return or re-seed for next year in your zone. This is a quick temporary fix for your bank. To be clear there are different types of rye grass seed, perennial, winter, annual, etc and annual rye grass seed will not return next year or re-seed but will grow quickly with adequate water and sun and could provide a grassy area for this midsummer though fall . I suspect the recommendation for a hydro mat was due to your comment that the area is difficult to water. You might estimate the cost of the mat for your square footage as I suspect it could be pretty costly. What is your long term goal for this area?

The majority will die off next summer, but it can survive (even significant amounts) if we get a rainy one. The second year, it's usually gone. I might be inclined to return that if I could and get something else without the annual rye. If not, it should be OK to use, just keep in mind that the stuff might last longer than you really want.