g The primary detrimental effect of the presence of large amounts of biodegradable organic materials in water is . The primary detrimental effect of the presence of large amounts of biodegradable organic materials in water is . it rises to the surface and absorbs wavelengths needed by aquatic plants it causes the water to become murky it decomposes endothermically causing the temperature of the water to decrease below the limits within which most aquatic organisms can live it causes oxygen depletion in the water it causes death of bottom dwelling organisms because it agglutinates and settles to the bottom, poisoning bottom dwelling organisms