The festival, held at Chingford Park, is intended to celebrate the creek and educate people about what lives in the tributary of the Water of Leith.
"Then there's just music and fun, basically," Valley Project manager Tess Trotter said.
The event, now in its fourth year, was organised by a huge group of volunteers, Ms Trotter said.
"It has been a really fantastic day. The sun has been shining and everyone has told me it's been the biggest fest yet."