River Rock Next to a Concrete Patio: Drainage or Decoration?

Probe to Determine Function

Scrape back the rock. If only 1–2 inches deep, it's decorative—replace with grass. If 8–12+ inches deep or you hit a pipe, it's a French drain—keep it.

Grass Over a Gravel Drain

Grass above a drain zone dries faster; requires more frequent watering to stay green.

Investigate before removing; you may be dismantling a functional drainage feature.