South Dakota state Rep. Steve Hickey (R-Sioux Falls) penned a letter this week claiming homosexuality carries health risks, describing anal sex as a "one way alley for the garbage truck."

Hickey, a pastor and opponent of same-sex marriage, was motivated to write the letter after a lesbian couple announced plans to file a legal challenge against the state's gay marriage ban.

"Certainly there are board-certified doctors in our state who will attest to what seems self-evident to so many: gay sex is not good for the body or mind," Hickey writes in the letter, which he posted to his Facebook page. "Pardon a crude comparison but regarding men with men, we are talking about a one-way alley meant only for the garbage truck to go down. Frankly, I’d question the judgment of doctor who says it’s all fine."

He continues: "This indeed is a matter of being on the wrong side of history considering that historically, homosexuality has been a notable marker of the downfall of past civilizations, not their rise. It’s not hate for a physician to speak up about something that is harmful to human health."

Hickey submitted the letter to the Argus Leader newspaper. According to Talking Points Memo, the paper has not yet decided whether to accept it for publication.

The lawmaker had previously spoken out against the legal challenge in an interview with the Argus Leader, saying he was "surprised it didn't happen earlier."

"It's evidence of a progression away from the foundation was this nation was (built) on," he told the newspaper. "The spiritual ramifications for a nation that loses its moral rooting, moral basis, are substantial."