[Code of Federal Regulations]
[Title 40, Volume 24]
[Revised as of July 1, 2005]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR230.21]

[Page 264-265]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 230_SECTION 404(b)(1) GUIDELINES FOR SPECIFICATION OF DISPOSAL 
SITES FOR DREDGED OR FILL MATERIAL--Table of Contents
 
Subpart C_Potential Impacts on Physical and Chemical Characteristics of 
                          the Aquatic Ecosystem
 
Sec. 230.21  Suspended particulates/turbidity.

    (a) Suspended particulates in the aquatic ecosystem consist of fine-
grained mineral particles, usually smaller than silt, and organic 
particles. Suspended particulates may enter water bodies as a result of 
land runoff, flooding, vegetative and planktonic breakdown, resuspension 
of bottom sediments, and man's activities including dredging and 
filling. Particulates may remain suspended in the water column for 
variable periods of time as a result of such factors as agitation of the 
water mass, particulate specific gravity, particle shape, and physical 
and chemical properties of particle surfaces.
    (b) Possible loss of environmental characteristics and values: The 
discharge of dredged or fill material can result in greatly elevated 
levels of suspended particulates in the water column for varying lengths 
of time. These new levels may reduce light penetration and lower the 
rate of photosynthesis and the primary productivity of an aquatic area 
if they last long enough. Sight-dependent species may suffer reduced 
feeding ability leading to limited growth and lowered resistance to 
disease if high levels of suspended particulates persist. The biological 
and the chemical content of the suspended material may react with the 
dissolved oxygen in the water, which can result in oxygen depletion. 
Toxic metals and organics, pathogens, and viruses absorbed or adsorbed 
to fine-grained particulates in the material may become biologically 
available to organisms either in the water column or on the substrate. 
Significant increases in suspended particulate levels create turbid 
plumes which are highly visible and aesthetically displeasing. The 
extent and persistence of these adverse impacts caused by discharges 
depend upon the relative increase in suspended particulates above the 
amount occurring naturally, the duration of the higher levels, the 
current patterns, water level, and fluctuations present

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when such discharges occur, the volume, rate, and duration of the 
discharge, particulate deposition, and the seasonal timing of the 
discharge.