News coverage of a serious bloom of an algae which releases a toxic compound in Lake Erie and water use restrictions in Toledo has sparked questions about MWRA water.

MWRA water comes from the well protected Wachusett and Quabbin Reservoirs. These reservoirs have extremely low levels of the nutrients which cause serious algal blooms. Photos of Lake Erie near the Toledo drinking water intake are in sharp contrast to MWRA’s sources reservoirs. MWRA reservoirs are “oligotrophic” meaning that water is clean and clear, with water clarity over 25 feet down..

MWRA has a regular algae monitoring and response plan in place, tracking the low levels of naturally occurring algae which inhabit all natural water bodies, and has never seen levels which approached those seen in Lake Erie. MWRA has tested for the toxin suspected in the Toledo water system and the results were undetectable.

MWRA disinfects the water supplying the Boston metro area with ozone and UV light. While MWRA levels of the algal toxin are undetectable, in the unlikely event that they were to become elevated, ozone is considered effective at destroying the toxin.

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