Here’s the drainage fact unique to coastal blocks: an Oceanside gutter never carries just water — it carries a sand budget, continuously deposited and never self-clearing. The supply lines run year-round: wind lifts beach sand inland block by block; thousands of beachgoers track it up every walk street and crosswalk; and coastal landscaping sheds its own decomposed granite into the mix. Once in the gutter, sand behaves nothing like leaf litter: it doesn’t decompose, doesn’t float away on the next flow, and settles out of moving water the instant velocity drops — which makes it both the flowline’s most honest inspector and its most patient saboteur. The inspector role first: sand marks hydraulic truth, banking precisely where flow slows, so a persistent sand bar mid-run is a grade problem announcing itself — the flowline has a flat spot or a settlement, and the deposit is the survey. But the saboteur role compounds: each sand bar becomes its own small dam, slowing flow further, catching more sand, and converting a marginal grade into a standing-water frontage one storm at a time — while the trapped moisture works on the gutter’s joints and the pavement beside it. The management translation runs both directions. Maintenance: on beach blocks, curb-line sweeping is drainage maintenance, not cosmetics — a scheduled clearing of the sand budget before storm season is among the cheapest flood-prevention a coastal property buys, and reading the deposits before sweeping them (light, even dusting = normal supply; recurring bar at the same station = grade failure) turns the chore into the inspection. Design: where we rebuild beach-block gutters, the sand load shapes the spec — flowline grades held toward the firm end of the range so ordinary flows keep sand moving, flat spots engineered out with extra care, and transitions detailed so the budget passes through instead of banking. A beach town can’t fire its sand; it can only build gutters that were told the truth about their job.