Ruthanna Emrys’ 2022 A Half-Built Garden is a first-contact novel.
Judy Wallach-Stevens is alerted to soaring phosphate levels near Bear Island. Judy, wife Carol, and their infant Dori dutifully trundle off to see what is polluting the local watershed. The source could be some pre-Dandelion-Revolution industrial relic or perhaps someone who should know better is dumping chemicals improperly. The real reason? Aliens.
Judy and her family are now hip-wader deep in a first-contact situation.