The annual Watershed Environmental Poetry Festival is back in Berkeley on September 26 to celebrate its twentieth year. The 2015 festival is dedicated to its co-founder and former director Mark Baldridge, who died late last year. Baldridge was also deeply involved with Poetry Flash, which has been an invigorating force in the East Bay literary community since 1972. The festival will begin at 10 a.m. with a walk along Strawberry Creek led by poet and “eco-educator” Chris Olander and featuring readings by Emily Johnston, Maya Khosla, MK Chavez, and others. At noon, the main festivities will begin. This year, celebrated poets Brenda Hillman, Jane Mead, Francisco X. Alarcón, John Shoptaw, and — as always — poet laureate Robert Hass, will be on the main stage. But that’s just a taste of the long lineup of nature-oriented readings and musical performances that will continue until 4:30 p.m. at Martin Luther King Jr., Civic Center Park (2151 Martin Luther King Jr. Way, Berkeley). Tents, chairs, and carpet squares are provided, but sitting in the grass is also recommended, along with a farmers’ market lunch from around the corner.