NOVELTY - Non-toxic accelerated biological degradation of organic matter on the surface of aquatic sediments in water includes dispersing timed-release tablets of a dry particulate composition onto the water surface, dissolving the tablets in layers, releasing oxygen bubbles that loosen and resuspend the organic matter and the bacteria contained in the inner-core of the tablets.    USE - Used for treating contaminated water, particularly for the non-toxic accelerated biological degradation of organic matter on the surface of aquatic sediments in water. It may be used for treating acid-contaminated lakes and streams, and for the prevention of growth of aquatic algae.    ADVANTAGE - The invented method employs the use of a colorant that prevents the necessary light from penetrating the surface water.    DETAILED DESCRIPTION - Non-toxic accelerated biological degradation of organic matter on the surface of aquatic sediments in water includes dispersing timed-release tablets of a dry particulate composition onto the water surface, dissolving the tablets in layers, releasing oxygen bubbles that loosen and resuspend the organic matter and the bacteria contained in the inner-core of the tablets. The timed-release tablets of a dry particulate composition comprises (i) an inner core comprising at least one live microorganism strain in dormant condition including aerobic bacteria, facultative anaerobic bacteria, or yeast capable of forming cysts, endospores, or ascospores in adverse conditions; (ii) an inner-coating over the inner-core of a water soluble substance including polyethylene glycol or hydroxypropyl methylcellulose; (iii) an outer layer over the inner-coating of an oxidative alkali comprising sodium sulfate coated sodium carbonate peroxyhydrate particles; and (iv) an outer coating over the outer layer of a water soluble substance including polyethylene glycol or hydroxypropyl methylcellulose. An INDEPENDENT CLAIM is also included for a timed-release tablet of a dry particulate composition for treating contaminated surface waters.