Happiness, Part II

Twenty-four hours later, the billabong has percolated most of its contents back to the groundwater. I would guess there's about five gallons remaining here, and that's even with a steady light rain over the period.

And that's what makes this a detention basin more than a billabong, a vernal pool, or even a rain garden: its function is to slow down urban runoff, not trap it for months, just enough to restore some semblance of the natural pace of rainfall and absorption. As such, the plantings around it don't need to be true "rain garden" types, because the area doesn't really get boggy (in fact, the California Gray Rush I tried here didn't survive the summer). I'll be interested to see whether the
Platyglossis (Tidy Tips) I planted last year, which is more of a vernal-pool native, reseeds.