City Mangrove informational web page. Here you will find additional background information and resources related to mangroves, mangrove trimming, state laws and regulations, etc.

What is Nutrient Pollution?

Nutrients, like nitrogen and phosphorus, are naturally occurring – but can be too much of a good thing when found in high concentrations in our waterways.
These nutrients are very high in sewage, septic tanks, storm-water runoff, and fertilizers.
Nutrient pollution can contribute to algae blooms. Algae blooms turn the water green and smell terrible, smothering seagrass and killing fish -- they can even be harmful to humans.

Potential Sources of Nutrient Pollution

Fertilizers: Fertilizer is often over-used in residential landscaping. Biscayne Bay and our canals are extremely sensitive to excess nutrients, so we have to be sure to keep these nutrients out of the water to avoid algae blooms.
Septic Tanks: When not properly cared for, septic tanks can leak or flood – creating a land-based source of pollution that drains into our waterways. This pollution can also contaminate the aquifer, our drinking water stored underground. Always maintain your septic tank and have it regularly inspected.
Storm-Water Runoff: Storm-water Runoff is any type of water that doesn’t soak into the ground, but instead “runs off” down a drain or grate and into a waterway. Sometimes this water flows over polluted areas such as parking lots, roads, industrial sites, or yards, bringing contamination into waterways.

To view the City's Best Management Practices on reducing non-point source pollution and promoting the efficient use of water while maintaining our City beautiful please visit our Best Management Practices web-page

Tips to Reduce Nutrient Runoff Pollution

Minimize or eliminate fertilizer, herbicide and pesticide use—or switch to organic varieties that are not harmful
Plant native plants – they are naturally adapted to our climate and don’t require a lot of water and fertilizer
Avoid over-watering your lawn
Use mulch instead of herbicides to help control weeds
Sweep up debris – don’t hose down your driveway
Minimize or eliminate fertilizing in the summer months when rains are heavy
Have septic systems inspected and pumped out every 3 years
Routinely check your car for leaks and dispose of engine fluids properly
When washing your car at home, use detergents sparingly or bring your vehicle to a commercial car wash
Pick up trash, pet waste and litter around your yard and home


Storm Water/Nutrient Runoff Brochure [English]	Storm Water/Nutrient Runoff Brochure [Spanish]

Ongoing City Water Quality Projects

Florida International University Tide Gauge Sediment Elevation Study

Scope of Work

Coastal wetlands provide essential direct livelihood services to millions of people, as well as critical regulating services such as maintenance of water quality, protection from storms and erosion, and carbon sequestration. Measuring the vertical movement of the coastal wetland surface and its constituent processes, and relative local sea-level rise (SLR) is necessary to determine whether a wetland can keep pace with SLR.

3 monitoring stations have been installed throughout the City waterways as a part of this project, with two of the stations including both tidal and sediment elevation (RSET-MH) monitoring: (1) Inland Coral Gables waterway, (2) coastal Coral Gables waterway, and (3) Matheson Hammock Park/Preserve.

Tidal & Water Level Monitoring

Each of the 4 sampling stations include a pressure gauge (Level Troll with conductivity and pressure sensors) that is installed and referenced to NAVD88 and to RSET benchmarks. Water level data are recorded at 15 minute intervals. Locations for tidal stations include Blue Road and Islands of Cocoplum along the Coral Gables waterway where water surface height near coast and inland, to detect potential differences due to rain and canal discharge between inland and outflow waterway locations, are monitored. Mangrove forest water levels are monitored at each RSET site in Matheson Hammock Park and in Islands of Cocoplum mangrove forest areas (blue stars). As part of tidal station maintenance, pressure transducers are field checked with on-site water level measurements, checked and replaced as needed, and data downloaded monthly. All 4 stations are set up with a telemetry system to obtain real-time data (Updated data for sites Blue Road 4.0 and Islands of Cocoplum 4.0)

Tide Aware in Coral Gables

Sediment Elevation

Two sediment elevation monitoring sites have been established in mangrove forest areas. From the benchmark pipe, a RSET arm with 9 vertical pins is used to measure the height of the soil relative to the referenced benchmark (36 measurements total). SET measurements are conducted every 6 months. Feldspar marker horizons are established to assess vertical change in soil elevation due to deposition of sediments and organic materials.

Link to Live Data Feed

CREST buoy with autosampler at the Blue Road sampling site. Live stream data The buoy is called "CREST_1".

Coral Gables Water Quality Assessment Project Update Presentation to Coral Gables Waterways Advisory Board

Floating Wetlands Project with FIU

In collaboration with Florida International University, the city has installed two floating treatment wetlands -- a type of nature-based infrastructure on the waterway along Blue Road and Taragona Drive. These floating mats support plant growth on top of water and uptake the dissolved nutrients that can pollute our canals. Like a wetland where plants help clean the water passing through, these floating mats help clean the water they are placed in. The more the plants grow, the more nutrients they remove also known as phytoremediation. This is a 12-week study that will test the viability of several flowering plants in both fresh and slightly saline canals.

Coral Gables Virtual Community Discussion on Water and Water Quality

On November 5, 2020 the City of Coral Gables held a virtual community discussion on water and water quality. Below are the presentations and a link to the recording of that meeting.

Topics discussed during this meeting:

South Florida watershed
FIU Research and Water Quality Projects
Biscayne Bay Task Force and what is being done at the County regarding improving the health of Biscayne Bay.
Coral Gables Storm-water system
City Water Quality Initiatives and Programs
How residents and businesses can get involved

Link to recording of the Community Discussion: Coral Gables Virtual Community Discussion on Stormwater and Water Quality. November 5, 2020 - YouTube

Speaker Presentations

South Florida Watershed: FIU-Crowl Coral Gables Event [PDF]
Biscayne Bay Task Force Updates: BBTF-2020-Gables-Irela-Bague [PDF]
FIU and Coral Gables Water Quality Projects: FIU-BB-Coral Gables-Troxler [PDF]
Coral Gables Water Management/Water Quality: Coral-Gables-Water-Management-Presentation-Diaz-Anderson [PDF]