1.1 Prioritize upgrades of Sarasota County Government’s wastewater treatment plants to advanced wastewater treatment

Key Message: Treated wastewater can introduce nutrient pollution into surface and groundwater through permitted releases, unintentional leaks and spills, and use in irrigation. Upgrading Sarasota County’s Wastewater Treatment Facilities to Advanced Wastewater Treatment (AWT) standards will significantly reduce nutrient loads in treated wastewater, thereby minimizing environmental impacts.

Importance

Most wastewater in Sarasota County is processed by publicly operated regional wastewater treatment facilities (WWTFs), supplemented by a number of small, privately owned facilities. Nutrient treatment levels vary. State regulations mandate only secondary treatment, which does not significantly remove nitrogen or phosphorus. These nutrients can enter water bodies through emergency discharges or irrigation reuse. AWT offers a third treatment stage that can substantially reduce nutrient concentration. For instance, in 2018, the Bee Ridge WWTF discharged wastewater averaging 18 mg/L of total nitrogen (TN) and 3 mg/L of total phosphorus (TP). Upgrading to AWT would reduce those concentrations to 3 mg/L TN and 1 mg/L TP or less. Upgrades are especially important in areas using reclaimed water for irrigation.

Overview

Treatment Capacity

The Sarasota County region is served by six major and 22 minor WWTFs (Figure 1.1.1, Table 1.1.1). A new facility has been permitted in the City of North Port’s West Villages. As of 2018, permitted capacity totaled 49 million gallons per day (mgd) for major WWTFs and 0.674 mgd for minor ones. Actual treated volume from the six major WWTFs averaged 26 mgd—just 53% of total capacity.

While Sarasota County Utilities inspects facilities for regulatory compliance, little emphasis is placed on reducing nutrient pollution from the 22 small privately operated WWTFs. These should be prioritized for mitigation (see Chapter 6.1, Table 6.1.3).

Disposal

In addition to treatment, WWTFs must manage disposal. Permitted wastewater disposal options vary based on treatment level and include discharge to surface waters, reused for irrigation, or stored via infiltration basins or aquifer recharge wells (ASR) for subseqent use in the dry season, or permanently disposed by deep well injection. Only AWT effluent may be discharged to Southwest Florida surface waters (Grizzle-Figg Act) (Table 1.1.2). AWT water is also preferred for irrigation due to lower nutrient levels. In contrast, reclaimed water from secondary treatment contains higher nitrogen and phosphorus levels, which can exacerbate nutrient pollution—especially when not factored into fertilizer calculations (see Chapter 1.2).

Only one local WWTF—the City of Sarasota facility—currently meets AWT standards. The City of Venice meets AWT criteria under rare conditions requiring surface discharge. Other facilities, including Bee Ridge, Central County, and Venice Gardens, discharge higher nutrient concentrations (Figure 1.1.2). Improvements in plant efficiencies since 2019 have lowered effluent nutrient concentrations at the Bee Ridge facility.

In 2018, wastewater effluent from the six major WWTFs in Sarasota County contributed an estimated 750,844 pounds of TN and 147,470 pounds of TP to the environment (Table 1.1.3). Nitrogen loads would be reduced by 69% or 83%, respectively, if AWT or NNC thresholds were achieved. Phosphorus loads would be reduced by 47% or 74%, respectively, if AWT or NNC limits were met.

Cost, Return on Investment, and Support for Upgrading WWTFs to AWT

Upgrading secondary-treatment WWTFs to AWT is a cost-effective strategy for reducing nutrient loading in surface waters. In 2017, the Florida Stormwater Association (FSA) compared the cost of reducing nutrients in stormwater versus AWT treatment by examining five Florida WWTFs that upgraded to AWT (FSA 2017). Based upon a 20-year project life, the annual operating and maintenance costs and annualized capital costs for AWT treatment were divided by the pounds of nutrients removed annually.

Annual removal costs for TN ranged from $11–71 per pound. Annual removal costs for TP varied from $9–1,259 per pound. In comparison, FSA found that the average annual cost of removing TN in stormwater through best management practices (BMPs) was $268 per pound, and the annual removal cost for TP was $1,052 per pound. FSA concluded that “costs for removing nutrients from surface waters (stormwater) were 8–10 times higher than those for treating or managing nutrient removal at the wastewater source.”

The Sarasota Bay Estuary Program (2022 CCMP Activity WQQ-6.1) and the Coastal & Heartland National Estuary Partnership (2025 CCMP WQ Activity 4.1) support AWT upgrades to wastewater treatment in Sarasota County as a priority management activity for water quality improvement in their Comprehensive Conservation and Management Plans (SBEP 2022, CHNEP 2025).

Progress and Commitments

In 2019, Sarasota County Government entered into agreements with Suncoast Waterkeeper and FDEP to resolve unauthorized discharges from the Bee Ridge wastewater storage ponds into Phillippi Creek, as well as sanitary sewer overflows occurring within the watershed. Sarasota County committed to improving wastewater collection, treatment, and disposal through investments in both short-term and long-term fixes. Short-term fixes included reclaim system upgrades and pump station modifications. Long-term solutions involved aquifer recharge wells, interim testing, and facility improvements.

Improvements to internal wastewater treatment processes at the Bee Ridge facility have reduced nitrogen sufficiently to allow effluent to be discharged to two Bee Ridge Recharge Wells during wet weather. The County also implemented a Sanitary Sewer Overflows and Capacity, Management, Operation, and Maintenance (CMOM) Program to improve wastewater collection system improvements to minimize the likelihood of sanitary sewer overflows (see Chapter 1.3).

Most importantly, Sarasota County secured a $105 million federal loan to support a $280 million upgrade of Bee Ridge WWTF to AWT. The project will increase capacity from 12 to 18 mgd and reduce effluent nitrogen from 10-20 mg/L to no more than 3 mg/L. Operational by late 2025, the upgrade project earned an Envision Gold Award in 2024 for sustainable design.

The County has also committed to upgrading Venice Gardens and Central County WWTFs. Venice Gardens will increase capacity from 3 mgd to 6 mgd at an estimated $150 million. Central County’s upgrade is more complex due to space constraints. Upgrades to capacity and transmission lines connecting flow between the three facilities will accommodate projected future growth in wastewater collection, including septic to sewer conversions (see Chapter 2.3).

Sarasota County Solid Waste is improving the quality of the leachate from the Central County Landfill that is sent to the county’s wastewater treatment facilities. Installation of a Leachate Tank Aeration System is scheduled for completion in April 2025. A reverse osmosis project that can remove up to 80% of ammonia in the leachate will begin construction in 2025, and associated leachate storage ponds will be completed by fall of 2025.

Approach

Sarasota County Government should continue to work toward completion of the upgrade and expansion of the Bee Ridge WRF. Upgrades to the Venice Gardens and Central County WRF should continue to be prioritized, funded, and implemented by Sarasota County Utilities. In addition, AWT upgrades to the central wastewater facilities of the City of North Port and the Englewood Water and Sewer District, as well as the City of Bradenton, should be prioritized, in order to help protect surface waters throughout the Sarasota County region.

Sarasota County Utilities should evaluate, prioritize, and convert privately owned small package plants to central utilities, as new AWT capacity comes online. In the meantime, effluent discharge percolation ponds should be monitored for nutrient loading to groundwater (see Chapter 6.1) and denitrification interventions like wood chip baskets should be implemented.

The County should continue to communicate environmental benefits and cost savings for AWT upgrades to the community. Benefits from these investments should be tracked and reported to the community, including reduced pounds of nutrient pollution entering the environment due to releases, spills, leaks and irrigation water. Cost savings of removing nutrients from wastewater effluent should be compared to typical nutrient removal costs from surface waters using equivalents of $268 per pound of total nitrogen and $1,052 per pound of total phosphorus.