Illinois Pollution Control
    Board
    April
    iLl,
    1971
    In the matter of
    )
    )
    )
    #R71—2
    Revisions of
    Mississippi
    River
    )
    Standards for Turbidity,
    )
    Dissolved Solids and Inorgai~iic
    )
    Solids
    )
    Opinion of the Board
    (by Mr. Currie)~
    On December 23, 1970 Mr. Robert Hartley of the Federal
    Environmental Protection Agency sent to the Pollution Control
    Board a summary of exceptions to the Illinois interstate water
    quality standards.
    The letter contained the following:
    “SWB~l2,13.
    Specifically remaining to be resolved on the
    Mississippi SWB—l2 and SWB—l3 are compliance schedules for
    secondary treatment and the inclusion of turbidity and
    dissolved solids criteria.
    In addition in SWB-~13, Zone
    2 should include inorganic solids~.
    At its January
    6,
    1971 meeting the Board proposed revisions
    to SWB~l2and SWB—l3 designed to extend to the entire river the
    prohibitions
    on turbidity and inorganic solids which had applied
    only
    to the portion opposite Iowa,
    The revision also added a limit
    for dissolved solids of 500 mg/I
    as
    a monthly average and 750 mg/I
    at any time thatvs identical to that specified for water supply
    sectors of
    all other Illinois waters.
    In accordance with the Statute, the Board held a public
    hearing on February 16,
    1971 in Edwardsville on the proposed
    revision.
    At that hearing Mr. Ernest Bennett of the Bureau of
    Water Pollution Control, Illinois Environmental Protection Agency
    testified in support of the proposed revisions as follows:
    “Mr. Currie:
    Mr.
    Bennett, what
    is the reason why deposits
    of inorganic solids should be avoided?
    Mr. Bennett:
    .
    .
    .Certainly the deposition of inorganic
    solids on the bpttom can change the aquatic environment
    for instance in a dr~dgingoperation, you work up inorganic
    solids, then deposit them downstream, you can alter
    the
    aquatic habitat.
    I
    477
    Mr.
    Currie:
    So that you could, among other things, have
    a detrimental effect on the bottom biota by covering up
    their habitat?
    Mr.
    Bennett:
    Right, definitely,
    Of course, the additional
    turbidity, either organic or inorganic in the stream,
    causes an esthetic degradation of the stream, that is,
    appearance and soon of turbidity.
    Mr.
    Currie:
    And might the turbidity also interfere with
    fish life in some way?
    Mr. Bennett:
    If a sufficiently high level, yes.
    The
    turbidity in the stream produces pot hills which oould
    otherwise affect fish as well as destroying their food
    source.
    Mr.
    Currie:
    And
    I take it turbidity would interfere
    with the passage
    of light to the lower areas?
    Mr. Bennett:
    Yes.
    Mr. Currie:
    And interfere with photosynthesis in the
    water as well?
    Mr. Bennett:
    Yes, again, when we are talking of the
    Mississippi River, our water is sufficiently deep that
    light penetration at the bottom is of little consequence.
    Mr.
    Currie:
    But turbidity would reduce the depth to
    which the light would penetrate and therefore the depth
    at which photosynthesis can take place?
    Mr. Bennett:
    This is correct.
    In summary, the revisions consist of minor changes in SWB—12
    and SWB—l3 to bring those regulations into conformity with those
    covering all other Illinois streams.
    I, Regina E.
    Ryan,
    do certify that the Board
    pted the
    above opinion this
    /4~
    day of~
    —,
    1971.
    1
    —
    478

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