SIOUX FALLS Three dudes enjoying the sunset together.

PORTLAND POST-PUNK TRIO Sioux Falls convey a looming sense of despondency and self-hatred in their music, but it oscillates between billowing vulnerability and brief, hopeful moments of human connection.Their debut LP, Rot Forever, is a 73-minute bruising epic that sticks with you. Flares of Fugazi-influenced chaos are followed by interludes of subdued tenderness, beautifully contextualizing the songs with each other.

"I guess I've been drawn to art that is big," says guitarist/vocalist Isaac Eiger. "With a book like Infinite Jest or a movie like Magnolia or an album like The Lonesome Crowded West, they're big enough that you can fit a ton of shit into them and there's no ceiling for what can be covered emotionally. I like it in any type of art, where people try to cover every type of feeling, and they aren't just limited to despair or elation. Maybe if you're really good, you can condense it into a 25-minute record, but I think I need more time."

Rot Forever is a long time coming for Sioux Falls, who've been through five EPs and six drummers since starting out in 2009. Founding members Eiger and bassist/vocalist Fred Nixon began playing together during their junior year of high school in Bozeman, Montana. The two shared a love of the western-tinged rock 'n' roll of Modest Mouse and Bozeman cow-punk group the Touchers.

"Sioux Falls didn't actually become a thing 'til about 2010, since we were mostly jamming on Modest Mouse covers in our drummer's basement. Lots of 30-minute renditions of 'Dramamine,'" says Nixon, who also designs all of the band's album art and merch.

After graduating from high school, Eiger and Nixon saved up money and moved to Portland in 2011, where they played mostly empty shows. After posting a Craigslist ad in late 2013, Nixon and Eiger solidified the group with drummer Ben Scott and recorded their third EP, Lights Off for Danger. In 2014, they befriended local bands Snow Roller and Blowout, each part of the loosely defined Semi-OK Collective. All three bands have become fixtures in Portland's current DIY-punk resurgence, each of their homes acting as part of a web of local house-show spaces. Members of those bands are featured on Rot Forever, too, with Tyler Bussey (guitarist for Snow Roller and The World Is a Beautiful Place and I Am No Longer Afraid to Die) playing banjo on "Practice Space," and Laken Wright (vocalist/bassist of Blowout) adding backing vocals on "Soaked in Sleep."

"I didn't feel any sort of connection to the Portland music scene before meeting our friends now," says Eiger. "The record is probably about loneliness. Or maybe it's not, maybe I just think it is."

Rot Forever maps an unsettled world, gradually reaching a crux in the brooding eight-and-a-half-minute song "If You Let It." Starting simply with a sludgy guitar, the track becomes a bubbling froth of anxiety. At its breaking point, Eiger recounts a memory of reaching out to his crying sister: "Ellie you'll be okay/Sometimes it feels so horrible/But you know you can't push it away." It charts a definitive moment of connection in their parallel isolation, as Eiger screams, "It goes away if you let it/Some Saturday you'll forget it."

The album could end at this impassioned peak, but it continues with "The Winner," a two-minute song in which Eiger, with tongue in cheek, concludes he's his same self-deprecating self: "Eating Jell-O for dinner/If life's a contest, I'm a winner." But Nixon's warm bass line and the clear guitar melody at least hint at a change for the better.

"This is not an album I would make now," says Eiger. "I feel like I purged it. Since I was a teenager, around 15, I wanted to make a record like Rot Forever. Then we did that, and I feel no need to do it again."

Sioux Falls would be the first to tell you they aren't the band they were yesterday. And while Rot Forever could be described as a meditation on feeling hopeless and alone, it succeeds because it recognizes there's a lot more to life than merely feeling that way.