Frequently Asked Questions

Blue-Green Algae

  • What is blue-green algae?

    Blue-green algae, or cyanobacteria, is a type of algae found naturally in aquatic systems around the world. Blue-green algae are microorganisms that function like plants in that they harness the sun’s energy to grow and reproduce.

    Blue-green algae are found in all of Florida’s freshwater and coastal habitats, including lakes, rivers and estuaries.

  • What causes an algal bloom?

    Although blue-green algae is found naturally, increases in nutrients can exacerbate the extent, duration and intensity of blooms. Other factors that contribute to algal blooms include warm temperatures, reduced water flow and lack of animals that eat algae.

    Although algal blooms can occur at any time, blue-green algal blooms is most common in Florida during the summer and early fall, when temperatures are highest and sunlight is abundant. The summer also brings frequent rainfall and larger storm events that have the potential to deliver excess nutrients into waterways through stormwater runoff.

  • Are all types of blue-green algae harmful?

    Some – not all – blue-green algae produce toxins that can contribute to environmental problems and affect public health. Environmental conditions that trigger toxin production are not completely understood. Over time, however, algal toxins are broken down and no longer pose a health concern.

    As indicated above, not all blue-green algae are toxic, but a non-toxic algal bloom can also harm the environment. Algal blooms can deplete the oxygen in water making it difficult for animals like fish to live. Highly concentrated algal blooms can also reduce the amount of light that reaches submerged plants on the bottom of lakes and estuaries with negative consequences for plant growth. In extreme cases, plants can die and important habitat for fish and other animals is lost.

  • Are algae blooms predictable?

    The nature of most blue-green algal bloom events makes it difficult to predict where and when a bloom will occur or how long it will last. However, lessening the negative effects of algal blooms is possible through reduction and other restoration activities. Reducing nitrogen and phosphorus in our waterbodies is an important step in decreasing the frequency, intensity and duration of algal blooms.

  • Can I tell If an algal bloom Is toxic by looking at it?

    No, this is why DEP coordinates with the water management districts and the Florida Fish and Wildlife Conservation Commission to routinely sample reported algal blooms. Collected samples are examined to identify the type of algae present in the bloom and are tested also for toxicity.

  • What are the health risks associated with algae blooms?

    The Florida Department of Health takes the lead in determining if an algal bloom presents a risk to human health. When appropriate, DOH issues health alerts and may also post signs when blooms could affect people using beaches or other areas where there is a potential for exposure. Toxins from harmful algal blooms (HABs) are known to cause short-term health problems; more research is needed, however, to better understand longer-term health impacts that might be attributed to algal toxin exposure.

    Direct contact with blue-green algal and their toxins can also cause short-term health related problems including, for example, respiratory distress.

    Decaying algae blooms including those dominated by blue-green algae can produce strong odors that may be unpleasant.

    Toxins produced by red tide forming algae, another type of harmful algal blooms, can be released to the environment as aerosols and can cause short-term breathing problems, especially in people who have respiratory illness such as asthma, bronchitis and emphysema.

  • What should I do if I see an algal bloom in a freshwater system?

    The state’s algal bloom response team encourages everyone to be on the lookout for algal blooms and report them. Residents statewide can now easily report algal blooms to the department 24 hours a day, 7 days a week.

    Information can be reported:


    To report fish that are either dead or in poor physical condition:


    People experiencing symptoms or illnesses that might be attributed to algal blooms:

  • What happens when an algal bloom is reported?

    DEP reviews public reports of algal blooms received via the online reporting form or hotline daily. DEP typically responds to the report by the next business day and evaluates and prioritizes the response based on severity of the bloom and potential for human exposure.

    DEP coordinates with other agencies who are also sampling our waters – primarily water management districts, the FWC and local government entities – to organize the response effort based on the location of the bloom relative to the sampling schedule for that day. Additional monitoring entities that reach out to offer sampling support are added to the schedule as needed. DEP, water management districts and FWC routinely survey and sample waterbodies throughout the state and are prepared to collect samples if algae is present.

    Whether algal bloom conditions are observed during routine sampling or in response to a citizen generated report, sampling teams enter the site visit information (location, bloom conditions observed and note whether a sample was collected) in real-time, which is currently displayed on the statewide blue-green algae map,  

    If a sample was collected for additional analysis, laboratory results are posted as soon as they are available.  The presence of blue-green algae and toxins in three of the major watersheds in South Florida are also displayed on the Water Quality Status map, along with other water quality indicators. This informational resource and will be expanded statewide during the next year.

  • How can I stay updated on algae blooms in my area?

    Visit the water quality dashboard to receive the most up-to-date information on water quality in Lake Okeechobee as well as the Caloosahatchee and St. Lucie rivers and estuaries. DEP is working now to expand its coverage on this dashboard to include waterbodies statewide.

    Residents can also subscribe to receive automatic email Algal Bloom Monitoring and Response updates.

    Receive Updates

  • Where are algal bloom samples tested?

    Most algal bloom samples are processed in DEP’s nationally recognized lab in Tallahassee.

  • What does DEP’s lab test for?

    Algal samples are inspected to identify the type of algae present. If the algae is a type that is known to produce toxins, the sample is then analyzed to determine if toxins are present and, if so, at what concentration. The toxins typically tested for include microcystin, cylindrospermospin and anatoxin-a.

  • How long does it take to test samples?

    Samples shipped to DEP’s laboratory in Tallahassee for algal identification and toxin analysis take approximately three to five days to process.

  • Who collects samples?

    DEP and Florida’s water management districts collect samples when algal blooms are observed during their routine water quality monitoring as well as when blooms are investigated after being reported by one of the department’s algal bloom response partners or private citizens. FWC coordinates algal bloom sampling efforts in nearshore, coastal and offshore marine waters.

  • How often are samples collected?

    DEP and Florida’s water management districts regularly monitor Florida’s water quality, and routinely collect algal bloom samples. Staff are deployed to take additional samples in response to reported algal blooms – whether from the public, other response team participants.

  • If a specific site or bloom is tested, is there a need for retesting?

    Yes, because toxins production can and does vary with time. Recurring and persistent blue-green algae blooms are routinely sampled and analyzed.


  • What is nutrient pollution?

    Nutrients, like nitrogen and phosphorus, are naturally present in the water and necessary for the healthy growth of plants and animals. On land, nutrients can boost plant growth on farms and within forests. But in the wrong place, in the wrong amount, nutrients can cause severe environmental damage with major economic consequences.

    Excess nutrients can, for example, lead rapid growth of algae, which, in turn, can degrade water quality with negative impacts to fish, wildlife and humans.  

  • How do nutrients find their way into our waterbodies?

    Nutrients such as nitrogen and phosphorus are introduced to aquatic systems as a result of a number of natural processes including, for example, the weathering of rocks and soil in a watershed.

    In the ocean, coastal upwelling is often a major source of nutrients. However, restoration efforts are focused on the human-related sources of nutrients which can include wastewater, water from septic tanks, stormwater runoff, and fertilizer runoff from both urban and agricultural lands. 

  • Why are water quality preservation and restoration efforts so focused on nutrients?

    Nutrient over-enrichment is recognized globally as one of the most pressing environmental challenges of our time. Addressing nutrient pollution in waterbodies is a priority for both state and federal managers and regulatory agencies.

    While traditional end-of-pipe controls can and have been effective at reducing nutrient inputs from wastewater treatment facilities, the diffuse, varied sources of nutrients call for innovative approaches and enhanced participation in nutrient reduction efforts by all stakeholders.

  • What is the state of Florida doing to reduce nutrient pollution?

    DEP is committed to addressing the problem of nutrient pollution in our state and is charged with monitoring and assessing Florida's surface water and groundwater quality; identifying, verifying and prioritizing pollution problems; developing strategies to resolve the problems; and implementing those strategies through comprehensive restoration actions in partnership with other governmental agencies and local stakeholders.

    The first step to water quality restoration is to adopt water quality standards that are based on rigorous science. Water quality standards establish allowable pollutant concentrations for individual waterbodies. These standards are based on the designated uses for the waterbody (e.g., recreation, water supply, aquatic life and/or agriculture). 

    Next, resource managers set restoration goals (targets) that limit the amount of nutrients and bacteria in a waterbody.

    After restoration targets have been established, DEP, in conjunction with local stakeholders, develops and implements a restoration plan to return the waterbody to healthy state. These restoration plans include a comprehensive set of strategies such as permitted limits on pollutant discharge from wastewater facilities, implementation of urban and agricultural best management practices (BMPs), and a broad suite of conservation programs designed to achieve nutrient reductions. 

    Each restoration plan can have several hundred projects identified to reduce nutrient inputs and restore water quality.

    Wastewater projects aimed at nutrient reduction include revision of permits, upgrades to wastewater treatment facilities, and/or redirection of wastewater discharges to reuse for irrigation and other water needs. Urban stormwater projects include, for example, "best management practices" for stormwater ponds. Local ordinances that result in reduced nutrient delivery to waterbodies (e.g., fertilizer ordinances) can be part of the plan as can public education efforts that promote Florida-friendly landscaping practices.

    All of these projects can occur at a variety of spatial scales including county-wide, city-wide, and within the boundaries of special districts. 

    Please visit State Action to learn more about what the state of Florida is doing.  

  • What can I do?

    You can stay informed and involved by following our progress via our email distribution lists or by regularly checking our website for tips that you can use to protect Florida’s Waters.

    It is also important to stay up-to-date on local policy changes and initiatives supported by your local elected officials as they pursue and implement long-term water quality improvement projects and strategies.


  • Are bacteria in the water a health concern?

    Bacteria occur naturally in all of Florida’s surface waters. The presence of certain bacteria, however, can present a human health risk if ingested while swimming or entering skin through a cut or sore.  

    Escherichia coli (E. coli) and enterococci, for example, are indicators of animal and human fecal waste and exposure to these types of bacteria, particularly at high concentrations, can lead to human disease, infections or rashes.

    When indicators of fecal contamination exceed the threshold for swimming, DOH advises against swimming in the affected waters, especially for vulnerable groups like children.

    Other bacteria, such as Vibrio vulnificus, are present in warm coastal waters during the summer months and can adversely impact people with weakened immune systems or especially chronic liver disease and diabetes. People can get infected with Vibrio vulnificus when they eat raw shellfish, particularly oysters. People with open wounds can be exposed to Vibrio vulnificus through direct contact with seawater. Although infections by Vibrio vulnificus are extremely rare, DOH recommends individuals with underlying health conditions listed above should not eat raw oysters or other raw shellfish.

    All people should avoid exposure of open wounds or broken skin to warm salt or brackish water or raw shellfish harvested from such waters. First aid for exposed wounds and broken skin should be conducted after exiting beach water with potable (drinkable) water and soap, plus a disinfectant like peroxide, alcohol or hand sanitizer.

Red Tide

  • What is a red tide?

    A red tide, or harmful algal bloom, occurs when there is a high concentration of a microscopic alga (plantlike organism). In Florida and the Gulf of Mexico, the species that causes most red tides is Karenia brevis, often abbreviated as K. brevis.

  • Is red tide in Florida found in estuaries, bays or freshwater systems?

    Red tide in Florida can occur in bays and estuaries, but not in freshwater systems such as lakes and rivers. Because Karenia brevis cannot tolerate low-salinity waters for very long, blooms usually remain in salty coastal waters and do not penetrate upper reaches of estuaries. However, other potentially harmful algae, including cyanobacteria (blue-green algae), more typically bloom in freshwater lakes and rivers.

  • Is red tide a new phenomenon?

    No, red tides were documented in the southern Gulf of Mexico as far back as the 1700s and along Florida's Gulf coast in the 1840s. Fish kills near Tampa Bay were even mentioned in the records of Spanish explorers.

  • How long do red tides last?

    Red tides can last as little as a few weeks or longer than a year. They can even subside and then reoccur. The location and duration of a bloom in the nearshore waters along Florida’s Gulf coast depends on physical, chemical and biological conditions that influence algal growth and persistence, including temperature, salinity, the amount of sunlight nutrient availability, and also the speed and direction of wind and water currents.

  • Can we predict where a red tide will occur and what its effects might be?

    Although the development of a red tide cannot be predicted, scientists can forecast its movement using wind and water current data once a bloom is located. Scientists can also monitor the concentration of the red tide organism causing the bloom by regularly collecting and analyzing water samples.

    Red tide movement and information related to the concentration of the algae that cause red tide are important because the potential effects of a red tide, such as dead fish and human respiratory irritation, are largely dependent on these factors. Accurate forecasting and regular monitoring allows people to make informed decisions regarding their beach-going activities.

  • Has coastal (nutrient) pollution caused the red tide in Florida?

    Red tides in Florida often develop 10-40 miles offshore, away from the direct influence of human generated sources of nutrients. In contrast to the many red tide species, in other parts of the world, that are fueled by nutrient pollution associated with urban or agricultural runoff, no direct link has been established between nutrient pollution in Florida and initiation of red tides caused by Karenia brevis or changes in their frequency of occurrence.

    Red tides occurred in Florida long before human settlement, and severe red tides were observed in the mid-1900s before the state’s coastlines were heavily developed. However, once red tides are transported to nearshore coastal waters, they are capable of using man-made nutrients to sustain their growth.

  • Where can I find out more about red tide?

    Please visit FWC’s website for more FAQs and information about red tide.

    More Red Tide FAQs

Drinking Water

  • Is Florida drinking water monitored for health and safety?

    DEP implements the Safe Drinking Water Act in Florida and has adopted U.S. Environmental Protection Agency (EPA) regulations and rules. DEP permits public water systems and works closely with Florida’s drinking water operators to monitor water quality and ensure drinking water standards are met.

    Drinking Water Fact Sheet

  • How do I know if my water is safe to drink?

    State and federal rules ensure that your water is safe to drink. The EPA sets the maximum allowable amount of a contaminant in drinking water. DEP conducts site inspections of Florida’s water systems and makes water quality test results available to the public.  Every public water supplier is required to report to their users that they are meeting water quality standards.

    Drinking Water Standards

Stormwater Management

  • What is DEP’s role in stormwater improvement projects?

    DEP works to protect and improve water resources with programs that provide grants and loans to local governments for projects that address stormwater treatment improvements and reduce stormwater nutrient pollution. Local governments can qualify to receive low-interest loans for stormwater infrastructure through the Clean Water State Revolving Fund (CWSRF).

    Stormwater treatment projects also may be eligible for funding through the Clean Water Act Section 319(h) Grant and the state's Total Maximum Daily Load Water Quality Restoration Grant.

    More on Stormwater Management

Domestic Wastewater

  • Who is responsible for wastewater regulations?

    More than 3,700 wastewater facilities are regulated by DEP. Nearly 1,800 of these collect and treat sewage from residential and commercial buildings. Additionally, there are nearly 1,900 industrial wastewater facilities, as well as agricultural sites throughout Florida.

    The basic function of the multi-step domestic wastewater treatment and disinfection process is to speed up the natural water purification process.

  • How is wastewater treated?

    Wastewater is subject to different levels of treatment. In a primary treatment system, screens, settling tanks and skimming devices remove sand, grit and larger solids from wastewater. In secondary treatment systems, air is supplied to support the growth of organisms that consume much of the remaining waste materials.

    In advanced treatment systems, an additional level of treatment, such as filtration, is sometimes provided to further reduce nutrients and impurities.

    Disinfection, the final stage in advanced wastewater treatment, removes disease causing organisms, such as bacteria, before the water is discharged or reused. 

  • What is reclaimed water and how is it different from domestic wastewater?

    Domestic wastewater, also called sanitary sewage, is the used water discharged from homes. It comes from everyday human activities such as bathing, dishwashing and toilet flushing.

    Reclaimed water, however, is treated wastewater that can be used for groundwater recharge, industrial processes, and irrigation of lawns, golf courses and agricultural fields. Using reclaimed water conserves drinking water supplies and is intended to reduce direct disposal into waterbodies.

    Domestic Wastewater

Sewer Overflows

  • What is an SSO?

    A sanitary sewer overflow (SSO) is any overflow, spill, release, and discharge or diversion of untreated or partially treated wastewater from a sanitary sewer Collection Transmission System (CTS), often caused by power outages, line breaks, inundation of the system or blockages.

    A sanitary sewer overflow can spill wastewater out of manholes or system collection points such as lift stations, and onto streets and into stormwater systems, surface waterbodies, or into toilets, sinks and drains, before it can reach a treatment facility.

    By taking the proper steps you can reduce the risk of SSOs and help to reduce the overall impact that SSOs have on water quality.

  • How does collecting oil and grease in a container or scraping it into the trash help with SSOs?

    Because a sewer system requires flowing water to function, anything non-water-soluble poses a risk to that system. Fats, oils and grease (FOG) come from: food scraps such as meats, dairy products or sauces; cooking residue; and cosmetic products or toiletries.

    When FOG enters a wastewater stream, it cools, thickens and then sticks to the inside of the pipe. This builds-up over time to create impediments and blockages which significantly reduce the effectiveness of the sewer system, are difficult and costly to remove or clean and can often lead to over-pressurization of a segment of sewer line resulting in a cracked or ruptured line which leaks untreated wastewater, an SSO.

  • How does minimizing water entering the sewer system during heavy rain storms help with SSOs?

    Sewer Collection and Transmission Systems (CTS) have miles of underground pipes which have been laid over years, sometimes decades, of various construction and expansion activities.

    Most utilities have maintenance plans to survey their pipes for integrity. However, over time, pipe integrity may be reduced or lost by: internal wear and tear; construction activity, i.e. digging, ground compression; tree roots; and over-capacity or high water pressurization.

    When a CTS loses integrity, the CTS is susceptible to infiltration from other water sources such as rainfall, which can lead to inundation of the CTS. When a CTS is inundated, the system may have trouble transmitting the higher-than-normal capacity, which can result in an SSO. When a CTS is inundated with stormwater or ground water, the wastewater treatment plant receives that mixed stream and is unable to distinguish between wastewater requiring treatment and other water which may not.

  • How do I help minimize SSOs during a power outage?

    A sewer Collection Transmission System (CTS) requires electricity to power the lift stations to pump wastewater through the pipes and for the wastewater treatment plant to receive and treat wastewater.

    When there is a power outage the lift stations cease pumping wastewater out of your neighborhood portion of the CTS. If there is a heavy rain-event in conjunction with the power outage, the CTS may be inundated and may already face SSO risk or be causing an SSO.

    When the power is out, minimize your wastewater use. Flush toilets only when necessary and never with any trash. Keep showers short to conserve water and minimize the water flow into the CTS. Also when power returns, recognize that most other people also plan to shower or flush toilets, wash laundry or use water in cleaning up.