Lake Alerts

Update: Lake Silver Lake Alert Lifted

May 22, 2015

The Lake Alert for Lake Silver has been lifted.

Since the last Lake Alert on May 15, 2015, the City has monitored the algal bloom, and tested the lake water for toxins that are sometimes produced by certain algae in the bloom.  For two consecutive weeks, the test results show toxin levels too low to measure.  Therefore, the Lake Alert is being lifted.

Please continue to exercise caution on the lake and refrain from using the lake for recreational activities if there is a noticeable algae bloom.  Please notify us if you observe anything unusual in the water.  Continue to stay informed on how you can reduce your personal pollution to the lake by visiting the City’s Stormwater website at

If you should have additional questions, please email us at




May 15th, 2015

Since the last Lake Alert, the City has monitored the lake on a weekly basis for microcystins. Each time the toxin concentrations were low ​and should not have caused unsafe conditions. ​ ​In the latest samples taken on 5/15/15, the toxin levels were undetected.

​We will take an additional sample next week. If this sample also yields undetectable microcystins the Lake Alert will be lifted. ​ ​In the meantime, please continue to exercise the necessary precautions.

If you should have additional questions, please email us at




May 1, 2015
The City was made aware of the unusual appearance of Lake Silver from several lakefront owners. Although Lake Silver has experienced periodic algal blooms, this recent bloom has a different appearance than those in past years. For this reason, the City took samples of lake water to identify the types of algae present.  There are three types of cyanobacteria (or blue-green algae) present in the bloom. More specifically, Cylindrospermopsis, Microcystis, and Pseudoanabena. As a result of this bloom, we are asking everyone to refrain from swimming, recreating and irrigating in/from Lake Silver until further notice.

For reference, cyanobacteria/blue-green algae are always present in the water. These blooms are caused by low-flowing,warm water and excessive nutrients that can come from a combination of fertilizers, septic tanks, yard waste and pet waste. Blue-green algae can pose a health concern based on its ability to produce toxins. Toxicity is hard to predict because a single species of algae can have toxic and non-toxic strains.  Even blooms caused by known toxin-producing species may not produce toxins or may produce toxins at undetectable levels.

The City had the water tested for microcystins (toxins). The sample taken on 4/29/15 came back with low concentration levels that should not cause unsafe conditions per guidelines set forth by leading health organizations. However, because of the potential for harm to humans and pets, the City will begin performing weekly microcystin testing until the algae appears to have died. If the toxin level should exceed safe conditions, the City will issue an additional Lake Alert. Please encourage your neighbors to register for the Lake Alert at so they too will get important information about Lake Silver directly.

In the meantime, as we stated above, the City would advise refraining from swimming, recreating and irrigating in/from the lake until further notice. Please be aware that as the algae dies, a “musty” or other unpleasant odor may occur.

The City has notified the Orange County/Florida Department of Health office and has requested assistance from the Florida Department of Environmental Protection. The City is also researching what treatment options, if any, are available and safe with minimal biological side effects.

We have attached a link for additional information:

If you should have additional questions, please email us at


What is a Lake Alert?

Lake Alerts are notifications posted, recorded or emailed when a City lake has a water quality concern. These notifications include the type of water quality hazard and severity of it. It also alerts the public when the water body is safe again for recreational purposes. Notifications will be posted on this page, recorded at 407.246.2220 and emailed to those who sign up to receive Lake Alerts in their inbox.


Avoid Naegleria fowleri and primary amoebic meningoencephalitis (PAM)

Parasitic disease caused by Naegleria is very rare — only a few hundred cases have ever been reported, however, a few common sense precautions will protect people from acquiring this and other water borne infections:

  • Avoid swimming in very warm water, especially if it is shallow and/or stagnant (not moving). The majority of PAM cases have resulted from exposure to water that is 26°C (80°F) or warmer.
  • Avoid taking in water through the nose while swimming, diving, water skiing or jumping into water. A nose clip can be used to prevent water being forced up the nose.
  • Stay out of the water if “No Swimming” signs are posted.
  • Do not swim in swimming pools that are very warm or that are not properly maintained, even if the water is chlorinated. Naegleria fowleri is resistant to chlorine.

Know the facts about health concerns related to blue-green algae exposure

Blue-green algae are simple plants that appear in water and wet areas. An algae “bloom” is a rapid buildup of algae that creates a green, blue-green or brown color on the surface of the water. They are often found in standing water in lakes and ponds near the shoreline. Warm, calm water and nutrients contribute to the rapid growth of algae. Blooms can occur any time of year, but are typically observed from the early spring to the fall in Central Florida.

Only a few types of blue-green algae are known to produce toxins, however, there is no way to determine visually whether or not a bloom is toxic. If you suspect an algae bloom is present, it is best to stay out of the water, keep pets away and contact the City of Orlando Stormwater Hotline at 407.246.2370. If you do contact the water, wash thoroughly with a clean source of water. Do not use the affected water for drinking or cooking, as toxins cannot be removed with filtration, boiling or chemical treatments. However, activities near the water are safe. Eating fish caught during a bloom can pose a health risk.

If swallowed, toxic algae can cause diarrhea, nausea, cramps, fainting, numbness, dizziness, tingling and paralysis. Skin contact can cause rashes or irritation. Children and pets are at greatest risk.

Characteristic images of algae blooms:


Appears as green paint spill on surface or appears as spongy green mat on surface


The sanitary and stormwater sewers are two separate systems in the City of Orlando, meaning that stormwater enters natural waterways through storm drains, and sanitary sewage (wastewater) is transported for treatment to the wastewater plant. Despite this separation, following unusually heavy rainfall there is the potential for sanitary sewage overflow, which can carry bacteria from untreated sewage onto paved areas, into storm drains and into our lakes commonly used for recreational purposes.

In short, please delay your recreational activities at the lakes until 48 hours following an unusually heavy rainstorm, particularly those activities that involve people or pets entering the water directly or during which water could be swallowed (examples: jet skiing, water skiing or swimming). People who fish within the 48-hour window should wash their hands after touching the water. Anyone who wants to eat fish caught in the City lakes within the 48-hour window should cook them thoroughly to kill bacteria.

Why 48 hours? Over the 48 hours, lakes left standing without disturbance provides time for any bacteria to settle to the bottom, somewhat purifying the surface water.


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