What is a Rust Tide?

Harmful algal blooms impact local water sources and environments. Rust tides are one of the many concerns for local officials who want to revamp local cesspools and septic systems to reduce the risk of these blooms occurring.

What is a Rust Tide?

A “rust tide” is a type of red tide caused by a bloom of the organism Cochlodinium polykrikoides. This type of bloom first appeared in Suffolk County waterways in 2004, resulting in a widespread and intense reddish-brown coloring of the water, which is why it’s been locally referred to as the “rust tide.”

Since these marine organisms cannot live in freshwater, they’re found primarily in:

  • Saltwater
  • Estuarine waters

You’re most likely to experience a rust tide in warmer waters. Late summer is a common time when the rust color becomes abundant, and locals really notice the change in the water sources around them.

What Causes Rust Tides?

Multiple factors contribute to rust tides. The two main factors that are contributing to red tide issues in Suffolk County are:

  • Nitrogen-rich waters, often caused by wastewater from older cesspools and septic systems
  • Water warming, which is allowing the algal blooms to grow

Local governments are trying to find ways to help reduce the nitrogen in waterways, and one method is to incentivize septic and cesspool updates to newer systems that reduce nitrogen content.

Harmful Effects of a Rust Tide

While rust tides are not harmful to humans, they are highly toxic to marine life, posing significant risks to the local environment and economy. Fish and shellfish often try and swim away from these toxic blooms, but when the bloom is severe, it’s difficult to avoid the rust tide.

Exposure to the tide leads to gill damage.

Younger fish and shellfish are particularly susceptible to gill damage, which has led to mass deaths. Local fishing economies and marine life are impacted the most, as many of the fish die off.

Adding to the damage of rust tides is the potential of reduced oxygen levels in the water.

Oxygen depletion occurs when the Cochlodinium die. Once dead, the cells sink to the bottom of the waterway, and bacteria begins to consume the cells. The process leads to oxygen depletion. When a rust tide is massive, the process can lead to severe oxygen depletion in the waterway, which has a direct effect on the marine life in the water.

Since its first appearance in Suffolk County in 2004, this bloom has recurred regularly. Fisherman in the area reported a mass fish die-off in 2008 and 2009; Shinnecock Bay, Little Peconic Bay, Peconic Estuary and Noyack Bay experienced similarly high fish mortality rates that year that were directly attributable to the rust tide.

The rust tide (and similar harmful algal blooms) have lead New York State, Suffolk County and individual towns to incentivize septic upgrade programs that offer homeowners the opportunity to recuperate some, or all, of the costs associated with updating their septic systems.

Innovative and alternative on-site wastewater treatment systems (I/A OWTS) help reduce the risk of harmful algal blooms and their associated damage to the local environment and economy by reducing or eliminating the nitrates that leach out of home septic systems. This, in turn, limits or eliminates the food source that is primarily responsible for these mass blooms.

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