What Causes Odors Around Our Lakes?

From time to time, residents may notice odors around retention ponds, especially during warmer or drier weather. These odors are typically caused by natural environmental conditions and normal stormwater processes. They are monitored by us and are not considered a public health concern. Below are common culprits of these odors:

Low Rainfall and Dry Conditions

Extended dry periods reduce inflow and natural flushing of retention ponds. Water becomes more stagnant and warms more quickly. As temperatures rise, dissolved oxygen levels in the water decrease.

  • What residents should know: Less rainfall often leads to stronger odors, not weaker ones. This is a natural response of stormwater systems during dry weather. These odors do not indicate sewage, contamination, or a failure of the stormwater system.

  • What residents can do: Avoid dumping yard waste or grass clippings into ponds. Limit fertilizers use near pond edges. Report unusually strong or persistent odors to the district so conditions can be evaluated.

Low Oxygen Levels in Pond Water 

Warm temperatures and stagnant water reduce oxygen levels. Organic material naturally decomposes at the pond bottom and consumes oxygen. Algae also use oxygen, especially overnight, which can further reduce dissolved oxygen.

  • What residents should know: Low oxygen is the most common cause of sulfur or rotten egg type odors around ponds. These conditions are usually temporary and can be managed through proper stormwater maintenance.

  • What residents can do: Avoid disturbing pond bottoms. Understand that fountains and bubblers are installed for water circulation and oxygenation and serve a functional purpose rather than a decorative one.

Decomposing Organic Material 

Leaves, grass clippings, fertilizer runoff, and plant debris can enter ponds through stormwater runoff. Dead algae and aquatic plants also break down naturally over time, contributing to odors.

  • What residents should know: Stormwater ponds are designed to collect runoffs and debris to protect downstream waterways. Odors tend to increase when organic material accumulates, particularly during warm weather.

  • What residents can do: Keep grass clippings and leaves out of streets and storm drains. Maintain shoreline vegetation buffers. Follow local fertilizer application guidelines to reduce nutrient runoff.

Algae Growth 

Algae growth is driven by excess nutrients combined with warm temperatures and sunlight. Limited water movement during dry periods can allow algae to increase.

  • What residents should know: Algae related odors are typically earthy or musty rather than sewage like. Some level of algae presence is normal in stormwater ponds and does not indicate a health hazard.

  • What residents can do: Reduce nutrient runoff from lawns and landscaped areas. Allow approved treatment methods when necessary. Support long term nutrient management and stormwater protection efforts within the community.

See our Lake Maintenance Schedule to find out when and which lake our staff will conduct maintenance.

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