Septic drainage spot in yard, advice please.

I bought this home in 2011 and the spot in the yard was present but has grown since then. I usually only deal with it in the spring time when it stays wet for months in end. Once summer hits, it dries up and the only time I notice it is if it rains for several days. As you can see, nothing grows on it until it dries up in summer time and then it’s usually crab grass.

This spot is almost at the bottom of our yard, rather decent slope. There are no other spots in our yard and the septic system as a whole seems fine. No backing up in the house, all plumbing is functioning normal. Once thing to note, our household increased in size from 3 to 5, 4 years ago. We added two teenage girls that take a ridiculous amount of showers.

I’ve beem reading up on septic leakage and draining. What are you thoughts on why the one large spot? Backed up drainage in other areas that force all the water down this drain pipe? Bad soil? We do have lots of clay.

I’ll be calling out a professional soon, just want some ideas before they arrive.

Well your drainlines are doing what they are supposed to and are functioning, the problem is you don't have enough lines to handle the amount of water you are using and the lines are saturated. When your lines load up due to excess usage may it be loads of laundry, many showers or excess rain it pushes out into your yard. That spot is most likely one of the lowest parts of your yard or line cover and most probably at the end of one of the trenches. If it didn't come up in your yard it would back up in your house. You need to add 100 foot of additional lines to fix your problem.