6.4 Adopt or update local ordinances to provide guidelines for stormwater pond management

Key Message: Stormwater ponds and canals must be maintained to retain their nutrient removal efficiency, yet are generally lacking in long-term maintenance. Local ordinances would provide a mechanism for outreach, inspection and certification to ensure that stormwater ponds and canals are managed and maintained to maximize nutrient removal.

Importance

Sarasota County has 4,666 stormwater ponds and more than 600 miles of drainage ditches and canals that collect and “treat” suburban stormwater prior to discharging to water bodies. Stormwater ponds are predominantly privately owned, while ditches and canals are primarily publicly owned. Ongoing maintenance of ponds in older developments, if it occurs, is usually the responsibility of property owners or community associations. Chronic algal blooms, overgrowth of exotic/invasive plants, absence of plants, eroding shorelines, and excessive trash are common. Removal of accumulated sediments, harvesting of aquatic weeds and replanting of vegetation is periodically required to ensure effective operation.

Algal blooms and trash are common maintenance issues in stormwater ponds. Source: Stocking Savvy

Local ordinances are needed to ensure that stormwater ponds retain their nutrient removal efficiency and other design purposes. Once codified, best management practices (BMPs) could be incorporated into private maintenance contracts. City and county maintenance contractors also could implement the BMPs for publicly owned stormwater systems, such as the 372 miles of swales managed and maintained under Sarasota County’s National Pollutant Discharge Elimination System (NPDES) permit (Sarasota County 2018b). Better management of stormwater pond systems to enhance nutrient reduction may simultaneously improve the biodiversity and health of the pond and adjacent property values.

Shoreline plantings in stormwater ponds help reduce nutrient pollution that causes algal blooms and provide habitat for birds and amphibians. Source: UF/IFAS Extension

Overview

Typical dry and wet detention stormwater systems permitted by water management districts under state stormwater rules must be inspected and certified every five years by a professional engineer to ensure proper operation and maintenance (SWFWMD 2018). Certified systems are intended to provide reasonable assurance that stormwater BMPs function as initially designed and permitted for both water quality and flood protection. In practice, stormwater ponds and canals are often not maintained well, and professional inspections can be cursory and focused on aesthetics and flooding concerns, rather than water quality performance. In fact, flood prevention, not water quality, is the stated maintenance goal for all stormwater conveyance systems on private property under Sarasota County Code (Sec. 54-555).

Potential stormwater pond management issues (University of Central Florida 2015) may also include:

  • Excess nutrients that stimulate algal growth;
  • Carcinogenic hydrocarbons that can threaten aquatic life;
  • Toxic heavy metals such as lead, zinc, iron, chromium, manganese, and copper;
  • Floatable debris; and
  • Bank erosion.

More detailed requirements and information on the cost and effectiveness of stormwater pond and waterway management are needed for property owners to improve maintenance outcomes for nutrients. Brief guides for homeowners and detailed manuals for pond maintenance contractors are available online (WMI 1997, SWFWMD 2000a, SWFWMD undated). Some communities have developed their own directives with the help of professional consultants and management experts. For example, the Gateway community in Fort Myers developed maintenance standards for its stormwater ponds, control structures, and wetlands. Their guidelines, intended for homeowners, HOA managers, and landscape and lake management contractors, address various water quality and habitat issues such as shoreline plants, trash, pet waste, erosion and sedimentation, illicit discharge, fertilizer use, and nuisance/exotic species. Gateway’s Maintenance Standards exceed the regulatory requirements of the South Florida Water Management District, Lee County, and the City of Fort Myers. Lee County residents can receive training in maintaining neighborhood ponds and lakes through the Watershed Education Training Ponds Lakes and Neighborhoods (WETPLAN) program sponsored by Lee County, City of Bonita Springs, Florida Gulf Coast University, Coastal & Heartland National Estuary Partnership, and local businesses. 

Educational guides and incentives for HOAs and homeowners can be helpful (see Chapter 7.1 and Chapter 7.2), but stormwater pond BMPs codified by ordinance will accelerate public awareness and, if incorporated into vendor contracts, facilitate compliance. Formal stormwater maintenance guidelines could eliminate conflicts between a local government’s vegetated ditch bank management and mowing and herbicide operations.

Approach

Sarasota County Government and municipalities could convene an intergovernmental task force to review and revise their current regulations for stormwater pond and waterway maintenance. A primary goal should be to adopt guidelines that ensure more efficient nutrient removal, and thus strengthen nutrient management. This process should engage local communities and lake and landscape management vendors with experience in stormwater pond management and contract administration. This would lead to development of management guidelines based on collective real-world management experiences, challenges, and solutions as well as desired community outcomes. In addition, the cost and effectiveness of various strategies for managing stormwater ponds could be evaluated (see Chapter 6.2)

For stormwater systems discharging to designated nutrient-impaired water bodies, BMPs that enhance nutrient reduction could be required in Reasonable Assurance Plans or Basin Management Action Plans. Existing stormwater system inspections required by SWFWMD permitting could be improved with assistance from local governments. Revised local regulations could require enhanced inspections in nutrient-impaired watersheds to certify that stormwater ponds and waterways function as designed for optimal nutrient reduction. Parcels served by certified stormwater systems could be eligible for stormwater fee credits.

Resources

Watershed Education Training Ponds Lakes and Neighborhoods 
http://www.wetplan.org/home.html

Status

No activity

Performance Measure

Local adoption of ordinances for stormwater pond management that enhance and perpetuate nutrient reduction efficiency.

Experts or Leads

Abbey Tyrna, UF/IFAS Extension Sarasota County; Mollie Holland, Sarasota County NEST; Ernesto Lasso de la Vega, Lee County Hyacinth Control District.

Cost Estimate

$50,000-$100,000

Related Activities

Chapter 6.2, Chapter 7.1, Chapter 7.2

 

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Other Stormwater System Activities

6.1 Estimate annual nutrient loads from stormwater

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