The code skeleton
A detached pergola or lath house of 400 sq ft or less is exempt only outside any fire district (Los Angeles Building Code section 101.5). The Very High Fire Hazard Severity Zone is a fire district (Los Angeles Municipal Code 91.7207).
The LADBS pool bulletin requires an enclosure for water 18 in deep or deeper (LADBS bulletin P/BC 2026-014). The basin in this courtyard is drawn shallower than that line.
A laboratory study of small and medium water features found that water sound masks road traffic by perception when its level sits close to the traffic level (a Heriot-Watt University study of water sounds).
A pool, fish pond or other body of water that must be fenced keeps its water clean and of reasonable clarity. A 6 in black disk on a white tile at the deepest point must be visible from the sidewalk at up to 10 yards (Los Angeles Municipal Code 91.8118).