Marion County, FL Stormwater Regulations

Unincorporated Marion County is a Phase II Small MS4 under FDEP's generic permit, and Ocala holds its own MS4 coverage. The county is split between two water management districts, SJRWMD and SWFWMD, so the district that issues your Environmental Resource Permit depends on which side of the line, roughly I-75, the property sits. Karst geology and the Silver and Rainbow springs drive extra local rules, and county code enforcement fines run up to $1,000 per day, or $5,000 per day for a repeat violation.

Primary source: Marion County Land Development Code, Article 6, Division 13 (Stormwater Management)

Permit Requirements

Marion County is split between two water management districts. SJRWMD lists Marion as a county only partly inside its boundary, and SWFWMD serves the rest through its Brooksville Service Office. SWFWMD has described the boundary as roughly Interstate 75. Your Environmental Resource Permit comes from whichever district covers the parcel, and each district applies its own design criteria, so confirm the district before design starts.

FDEP's NPDES Construction Generic Permit covers land disturbance of one acre or more. The county wants a copy of that permit or the notice of intent before construction begins.

At the county level, a Major Site Plan with full stormwater review is required when existing and proposed impervious cover equals or exceeds the lesser of 35 percent of the site or 9,000 square feet, when driveways generate 50 or more peak-hour trips, or when a 24-inch pipe or larger discharges project runoff. Smaller projects that could affect drainage still have to show the Office of the County Engineer they won't raise runoff above pre-development levels.

Inspection Obligations

During construction, erosion, perimeter and waste controls must be regularly inspected and maintained. Sites that disturb an acre or more also follow the inspection schedule in FDEP's Construction Generic Permit.

The county's Land Development Code doesn't set a fixed inspection interval for private permanent stormwater systems. Instead, the owner signs a perpetual operation and maintenance certification, and the O&M terms must be written into HOA or property management association covenants. Ongoing inspection duties come from the ERP operating permit issued by SJRWMD or SWFWMD.

Golf courses carry extra reporting. Courses in the county's Springs Protection Overlay Zone certify compliance with their Natural Resources Management Plan to the Office of the County Engineer every year, and FDEP's springs BMAP requires every golf course in the BMAP area to submit a nutrient management plan.

Penalty Structure

A Land Development Code violation is a non-criminal violation, and each day it continues counts as a separate offense. Under County Code Sec. 2-207, the Code Enforcement Board or a special magistrate can fine up to $1,000 per day for a first violation and up to $5,000 per day for a repeat violation, for each day past the compliance date. A violation found irreparable or irreversible can draw a fine of up to $15,000. A recorded fine order becomes a lien on the property.

On active sites, failing to install or maintain erosion, perimeter and waste controls can lead to an order to stop all work until the site complies. The county's fertilizer ordinance has its own schedule: written notice for the first two violations, then $50 and $100.

State enforcement runs alongside the county's. FDEP can act on NPDES violations and unauthorized discharges, and SJRWMD or SWFWMD can act on ERP violations in their part of the county.

Key BMPs

Marion County's water quality criteria are built around shallow systems that treat runoff before it reaches the aquifer. Systems that meet the county's criteria outright include:

• Shallow dry retention - Dry retention 4 feet deep or less with vegetative cover, or 6 feet deep or less with 4:1 side slopes and sodded bottoms. Pond bottoms must sit at least 1 foot above the estimated seasonal high water elevation.
• Wet retention/detention - Wet systems, including wetlands, that meet the governing state standards.
• Distributed volume - Shallow swales, bioretention or recessed medians that hold runoff within each sub-basin, sized at 75 percent of the change in initial abstraction (up to 1 inch) and recovering within 72 hours.
• Alternative treatment techniques - Systems that don't meet the criteria above need two of these per basin: limited direct discharge, pervious parking, stormwater harvesting, site preservation, impervious area limits, or other approved low impact designs.
• Required pre-treatment - Oil/water separators or comparable technology for car washes, body shops, vehicle and equipment repair, fleet operations and gas stations.
• Karst safeguards - At least 3 feet of unconsolidated soil between limestone bedrock and the bottom and sides of any stormwater facility, a 10-foot maximum facility depth, and no untreated stormwater into a karst feature.

Local Ordinances

The county's design rules are in Land Development Code Article 6, Division 13, last amended in 2025. Open and closed basins are both designed for the 25-year and 100-year, 24-hour storms, with post-development rate and volume held to pre-development levels. Where the County Engineer has validated downstream flooding, the limit tightens to at least 25 percent below pre-development. Closed-basin facilities must recover within 14 days.

Springs protection layers on top. The Springs Protection Overlay Zone restricts uses such as junk yards and unpermitted body shops in its primary zone. The karst rules require a 150-foot vegetated buffer around unremediated karst features with a direct aquifer connection and 75 feet around those without one, with no ponds, pavement, irrigation or fertilizer inside the buffer. FDEP's 2025 Silver and Rainbow springs BMAP covers an area that lies mostly within Marion County, and its Priority Focus Areas follow the county's primary springs protection zones.

The fertilizer ordinance applies countywide. No fertilizer goes on turf within 15 feet of the top of bank of a drainage retention area, canal or wetland, within 75 feet of Silver Springs, Silver Run, Rainbow Springs or the Rainbow River, or within 100 feet of an open sinkhole.

Unincorporated properties pay a stormwater assessment under Chapter 17, Article IV of the County Code. The FY 2026-27 rate resolution sets $15.00 per ESU maximum and $10.57 minimum, and one ESU equals 2,275 square feet. Inside city limits, Ocala bills its own stormwater utility charge per Equivalent Residential Unit of 1,948 square feet.