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1. To become contaminated or filled with silt (very fine sedimentary particles slightly larger than clay but smaller than sand). The stream behind our house silted up over the years, and now it is little more than a trickle.
2. To cause some body of water to become contaminated or filled with silt. A noun or pronoun can be used between "silt" and "up." Erosion caused by heavy rainfall has silted up the harbor, giving it a dirty, murky appearance.
[for a body of water] to become filled with silt. The river moved too fast to silt up. The lake silted up in a very few years.
1. To become filled with silt: The old canal had silted up.
2. To fill, cover, or obstruct something with silt: River sediments gradually silted up the harbor. Parts of the creek were now too shallow for boats because the storm had silted it up.