Louros
Louros is north of Aitoliko. Keep going through Aitoliko and north over the northern bridge. You will reach the village of Neohori. As you are leaving Neohori, going north, just before you get to the bridge over the river that leads to next village, Katohi, you will see a turn to your left. There used to be a petrol station there. Turn left. The road down follows a water channel on the right, orange and and olive groves on the left. There are several left turns off this road but you don't want the first couple. After a few kilometers (maybe 5 but I can't swear to it) you will reach a left turn with a sign for a fish farm. I think there is a sign to Louros as well, and I'm pretty sure there is also a white icon stand. If in doubt, stop passing traffic and ask if it is the way to Louros. There will be plenty of people going to the beach and they all drive like maniacs. Follow that road straight down o the water (a lagoon).
Once you have reached the water, you can turn right for Louros, (then left at the pump house--nt that there's a choice)which is a hugely long sand beach backed by lagoons. They can be worth an explore. There is a small lagoon by the beach that sometimes has flamingos. Otherwise the flamingos will be in the big lagoons in front of you as you approach, or off to your left. It's a big area but there were thousands of flamingos when we were there so you won't miss them. You can drive a long way along the dirt road circling the lagoon (going left/south) and eventully you will come out just above Aitoliko. You will see two dirt roads: one a higher embankent and a lower road. They run parallel. The lower road is in much much better shape. You can also drive out on all the causeways, and in summer when things dry up I guess people drive all over the dried-up areas of the lagoon. Depends on your car, I guess.
I can't guarantee how much is in these lagoons in summer--as I said, I like going there in winter. But you should find flamingos at least. Best of luck.