It is the purpose of this subtitle to provide certain remedies to abate the pollution, destruction, or substantial or unreasonable impairment of the air, water, or other natural resources of the State and therefore nothing contained in it abridges or alters rights of action or remedies which exist. A provision in this subtitle, or any act done by virtue of this subtitle, may not be construed as estopping or limiting the State or any person in the exercise of his rights to suppress nuisances or to abate any pollution.