national monument. noun. Definition of national monument for English Language Learners. : a place (such as an old building or an area of land) that is owned and protected by a national government because of its natural beauty or its importance to history or science. Britannica.com: Encyclopedia article about national monument.
Brown or discolored water is caused by minerals, sediment, or rust that may accumulate in the water mains over time. When the water from your tap is brown this indicates a disturbance in the water main that stirs up these deposits.
Suspended material in water bodies may be a result of natural causes and/or human activity. Transparent water with a low accumulation of dissolved materials appears blue and indicates low productivity. Dissolved organic matter, such as humus, peat or decaying plant matter, can produce a yellow or brown color. Some algae or dinoflagellates produce reddish or deep yellow waters. Water rich in phytoplankton and other algae usually appears green.