When a ditch clogs or a yard floods, the first question is whose infrastructure it is. In Pinellas County the answer depends on where the water is and where you live.
The county's role (unincorporated areas). Pinellas County Public Works maintains the public stormwater system in unincorporated Pinellas: county-owned pipes, ditches, ponds, and outfalls. This work is funded by the Surface Water Assessment, adopted in 2013, which appears on the TRIM notice and annual property tax bill of unincorporated property owners. The fee is based on impervious area (rooftops, driveways, parking): for FY27, one equivalent residential unit is $140.33 per year, with small homes paying $84.20, medium homes $140.33, and large homes $322.76; commercial parcels pay by measured impervious area (a supermarket example runs about $11,086 per year). The assessment funds pipe repair, drainage maintenance, flood reduction, and water quality work. City residents do not pay the county assessment; about 65% of county residents pay a similar fee to their own municipality. unverified
Cities. Inside St. Petersburg, Clearwater, Largo, and the other municipalities, the city's stormwater utility maintains public drainage and bills its own stormwater fee, usually on the utility bill or tax bill. Report city drainage problems to the city, not the county.
Private responsibility. Swales, ditches, and pipes on private property, and systems inside private communities (HOA-owned ponds, private streets), are the owner's or association's responsibility, including mowing and keeping them clear. Many neighborhood retention ponds that residents assume are government-maintained are actually HOA assets. Drainage easements crossing your lot generally let the government access and maintain its infrastructure but leave surface upkeep to you.
Bigger pipes, bigger agencies. SWFWMD regulates larger surface-water systems and permits new development drainage; FDOT maintains drainage within state road rights-of-way like US 19 and SR 60.
Reporting. For unincorporated flooding or blocked county drainage, use the county's reporting channels (pinellas.gov, the Pinellas County app, SeeClickFix, or 727-464-3000). Never fill, pipe, or obstruct a drainage feature without a permit; altering flows onto neighbors creates liability, and illicit discharges into storm drains (paint, oil, wash water) are code violations since storm systems drain to the bay untreated.