The sump pump mystery is solved. The garden hose in my neighbour's backyard came undone, and water had been seeping into the backyard for over a day, turning it into a well-watered but quite swampy lawn. I just wish some of it seeped over here to breathe a bit of life back into the grass. The weather apps aren't seeing rain for at least another ten days. I hope the farmers around me have the irrigation they need. There's definitely some moisture left in the backyard next door if they need it.