Recently the BMKCSD Waterway’s Manager noticed a reddish discoloration forming within the Navigation Locks (photo below).  Upon further investigation it was revealed to be a school of Brine shrimp (Artemia) genus of aquatic crustaceans.  Commonly referred to as Crill (whale food) they are the same organisms marketed and sold commercially as Sea Monkeys, or as fish food from pet stores.  Brine shrimp, as the name implies, are tolerant of a wide range of water salinity, but prefer higher concentration levels.

Sometimes Brine shrimp eggs will float to the surface and form mats which appear unsightly, however, they are relatively sensitive to the environment. Brine shrimp are a secondary consumer that eats microscopic planktonic algae and are themselves an important food source for larger predatory organisms. They tend to isolate themselves in areas away from predators when possible. Brine shrimp are not harmful, they do not bite, sting, produce toxins, and are not a vector for disease. Their presence is often seen as an indicator of a healthy and clean ecosystem.

We will continue to monitor and look at best management practices to keep them in the lagoons as they are an import food source in the lagoons.



Update 2/8/2021: 

This notice updates prior information regarding the algae observed in the Bel Marin Keys Community Services District (BMKCSD) North Lagoon and South Lagoon at the end of November 2020. Water samples from both lagoons were sent for testing. The BMKCSD was informed by representatives of the testing facilities and individuals with whom the BMKCSD consulted with, that the observed algae is of a non-toxin producing species. BMKCSD has therefore removed lock restrictions and has removed its prior recommendations regarding water contact.  

Please see the attached memo titled “Update on Algae Presence in North and South Lagoons” that is accessible by clinking this link Memo: Update on Algae Presence in North and South Lagoons.

 The BMKCSD continues to do monthly water testing. For the most recent and past testing results, please click the following link to water quality reports: http://www.bmkcsd.us/bmk-csd/water-reports/

 If you have any questions regarding this notice, please email the BMKCSD office at admin@bmkcsd.us or you may leave a message on the District voicemail at 415-883-4222. Additional information will be posted on the District website (www.bmkcsd.us). 


Previous Updates

Algae Update 12.31.20

Algae Update 12.18.20

Algae notice 12.9.20


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