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Algae Information & Acknowledgement

Each year due to environmental pressures on the water at the Rainbow Reservoir there is the possibility for a toxic algae bloom. It has become more likely as summers become hotter and drier and runoff from upstream fuels the growth of cyanobacteria in the contained environment of water held back by the dam. 

In recent years FVRA has written letters of support that have helped the Farmington River Watershed Association attain grant funding for cyanobacteria studies on Rainbow. While the studies help us better understand why the algae blooms are occurring we are not yet at a point that any kind of large scale prevention treatment or mitigation can occur. 

How do Cyanobacteria blooms affect me?*

There is no clear or easy way to quickly determine if a bloom is toxic, therefore when blooms occur health officials advise people and pets to avoid the water. Cyanobacteria toxins are among the most powerful natural poisons known. Cyanobacteria blooms – due to this risk of cyanotoxins – can harm people, animals, the aquatic ecosystem, drinking water supplies, the economy, property values and recreational activities such as swimming and fishing. Not all cyanobacteria blooms produce toxins, however, about 1 in 5 blooms do. There are potential health risks for swimmers, boaters, pets and wildlife encountering toxins that may be produced by the algae. Pets swimming in waters containing cyanobacteria toxins may become ill or die after drinking or licking themselves. Toxins associated with cyanobacteria have been implicated as the cause of mass mortalities of fish and birds. 

*From FRWA


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As rowers we are sitting right above the surface of the water where these Cyanobacteria live. Oars splash water on us while we are rowing, water can get on us while we are moving boats and the gasses released by the bacteria can irritate our airways. With all this in mind we are always keeping an eye out for algae growth both up and down stream and make every effort to avoid any areas with a strong algae presence. Many times we have been able to continue to row while an algae bloom has been occurring due to the inflow of fresh water washing the bulk of the algae to the “basin”, or wider area of the reservoir, allowing us to row in clean water upstream of our dock. Unfortunately this is not always the case and we may need to place a hold on all on-water activities until which time the algae has cleared from the majority of the reservoir. 

Timing & Options

The time frame for algae arrival is anywhere from mid-July through mid-September when temperatures are warmest and waterflow may be diminished. We will post updates on our website, online sign-out logs and email all FVRA participants should an algae bloom start to occur. 

If we need to stop going out on Rainbow there are several options for current members and program participants,

  1. Group On-Land Workouts – Participate in on-land workouts with a group focusing on technique and strength using weights and ergs
  2. Credit for Remaining Program Fees – Receive a credit of your remaining program fees for future FVRA programming when the algae has cleared
  3. Refund for Remaining Program Fees – Receive a refund of your remaining program fees
  4. Donate – Donate any remaining program fees to the club to help support our rowing programming both on and off the water
  5. Off-Site Group Rows – There is the option based on interest to cartop smaller shells to an alternate site at a scheduled time for a group row. Options include Lake Mcdonough in Barkhamsted, West Hill Lake in New Hartford or possible visiting rows with other local clubs. 

Toxic algae blooms are unfortunately something we need to anticipate as part of our use of the Rainbow Reservoir. A bloom occurring is not guaranteed but it is important that everyone is aware of what to look out for and have a plan in place should one start to appear. The FVRA Board appreciates your understanding as we do our best to continue to provide water access and programming while still keeping everyone clear of the hazards that cyanobacteria can bring. 

For more information on algae blooms and cyanobacteria visit: