Explanation:

Dissolved Oxygen (DO) is a measure of the amount of free oxygen available in river systems. Presence of organic and inorganic wastes in water decreases the dissolved oxygen content of the water.

• A number of factors like surface turbulence, photosynthetic activity, O2 consumption by organisms and decomposition of organic matter are the factors which determine the amount of DO present in water.
• The quality of water increases with an increase in DO levels.
• Water pollution by organic wastes is measured in terms of Biochemical Oxygen Demand (BOD).
• BOD is the amount of dissolved oxygen needed by bacteria in decomposing the organic wastes present in water. It is expressed in milligrams of oxygen per litre of water.
• The higher value of BOD indicates low DO content of water. Since BOD is limited to biodegradable materials, it is not a reliable method of measuring water pollution.

Hence both statements are correct.