When I did Owl's Head it was July with high water. I brought a pair of Teva sandals to wear when crossing the streams. On the way out, there was a couple, woman about 50 and the guy was in his sixties and they were at the second stream crossing. He had lost his boots, she lost her hiking poles and look wiped and they were both soaked but he was convinced that they would camp out and summit the next day. Someone had taken pity on them and given him a pair of size 12 sneakers (when he was an 8.5). They did not turn around that I knew. Better to bring the sandals or water shoes, cross the streams and put on dry boots and warm socks once over the second crossing. Also be aware that the water is very cold, even in July and feels like pins and needles.
Enjoy the trek. It is long but rewarding.