Marco Deficiency

The Marco waterways are negatively impacted by phosphorus in the reuse water from the Marco Island Wastewater Treatment Plant (WWTP). This has been proven by two recent technical studies and is seen in the water quality samples in depressed levels of Dissolved Oxygen (DO) and elevated levels of pH as well as visually from algal blooms. Marco Island is entering the death of the waterbody as a result of phosphorus in the WWTP reuse water. 

There are currently no FDEP limits placed on the phosphorus introduced into the Marco waterbody by the WWTP from reuse water. The Marco WWTP has an agricultural permit. The existing reuse water nutrient content is TN = 5 mg/L and TP = 3 mg/L.

An engineering study is required to define the alternative methods (costs, benefits and concerns) to reduce phosphorus and nitrogen in the WWTP reuse water, including but not limited to chemical precipitation and Advanced Wastewater Treatment:


Option A: Target Grizzle-Figg Limits: TN < 3.0 mg/L; TP < 1.0 mg/L

Option B: Target Limits of Technology (LOT): TN < 0.5 mg/L; TP < 0.1 mg/L


Potential Hard Benefits include:

• Eliminate current double pass through WWTP system to lower nitrogen levels in the reuse water: frees up WWTP capacity; reduce cost.

• Extra WWTP capacity can serve new sewer customers - increases revenue.

• Additional surplus clean reuse water can be sold to new reuse customers - increases revenue.

• Eliminates deep well injection as the reuse water is clean - reduces cost.

• Surplus clean reuse water can be used as supplement to raw water feed. The raw water supply will then be cleaner and potable water will be cleaner, as compared to using polluted stormwater runoff as a raw water feed.

• EPA estimates of cost might be as low as $1,000,000 to eliminate 99% of the phosphorus.


Potential Soft Benefits include:

• Avoids loss of tourist revenues (restaurants, hotels, rentals) to commercial interests and tax revenues to City of Marco from the negative image of dead water bodies - maintains tax revenue.

• Improved property values as public perception builds that the City is “Environmentally Friendly.”

• Continues to support the image of Marco as an “ecotourism” destination. Preserves existing ecotourism and sports fishing commercial revenues and tax revenues - maintains tax revenue.

• Improved water quality in Marco will improve the water quality of the Rookery Bay Estuary.

• Possible restoration of Marco water clarity to pre-development levels.

• Allows for the restoration of seagrass and shellfish to proceed. Must remove the phosphorus from the reuse water or these programs will fail.


This single investment may resolve the entire water quality issue here on Marco Island. As can be seen from the attached graphic, the polluted water from Marco Island is currently causing oxygen deficiencies in the 10,000 Islands to the South. DO > 5 mg/L indicates healthy water. If we do not clean the phosphorus out of the Marco reuse water, the negative impacts to the 10,000 Islands will continue and grow. Not only will Marco slip into a dead waterbody, we will drag the 10,000 Islands down with us.


Eugene Wordehoff

Citizen of Marco Island


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