MS4, or similar, may refer to:
* , a possible dwarf planet
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MS4 Modeling Environment, a software package
* ''
Metal Slug 4'', a video game
*
Mississippi Highway 4
Mississippi Highway 4 (MS 4) runs east–west from an intersection in the community of Fox Island west of Tunica, Mississippi, near the border with Arkansas, to MS 25 in Tishomingo County, Mississippi. It travels a distance of , serving Tun ...
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Mississippi's 4th congressional district
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Municipal Separate Storm Sewer System (MS4) required pursuant to United States law to regulate
stormwater runoff
Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when the s ...
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