ORDERED:
A. Paragraph 3 of the Decree entered by the Court herein on June
12, 1967, is amended to read as follows:
3. For the purpose of determining whether the total amount of
water diverted from Lake Michigan by the State of Illinois and its
municipalities, political subdivisions, agencies and
instrumentalities is not in excess of the maximum amount permitted
by this decree, the amounts of domestic pumpage from the lake by
the State and its municipalities, political subdivisions, agencies
and instrumentalities the sewage and sewage effluent derived from
which reaches the Illinois waterway, either above or below
Lockport, shall be added to the amount of direct diversion into the
canal from the lake and storm runoff reaching the canal from the
Lake Michigan watershed computed as provided in Paragraph 2 of this
decree. The annual accounting period shall consist of twelve months
terminating on the last day of September. A period of forty (40)
years, consisting of the current annual accounting period and the
previous thirty-nine (39) such periods (all after the effective
date of this decree), shall be permitted, when necessary, for
achieving an average diversion which is not in excess of the
maximum permitted amount; provided, however, that the average
diversion in any annual accounting
Page 449 U. S. 49
period shall not exceed 3680 cubic feet per second, except that
in any two (2) annual accounting periods within a forty (40) year
period, the average annual diversion may not exceed 3840 cubic feet
per second as a result of extreme hydrologic conditions; and, that
for the first thirty-nine (39) years the cumulative algebraic sum
of each annual accounting period's average diversion minus 3200
cubic feet per second shall not exceed 2000 cubic feet per
second-years. All measurements and computations required by this
decree shall be made by the appropriate officers, agencies or
instrumentalities of the State of Illinois, or the Corps of
Engineers of the United States Army subject to agreement with and
cost-sharing by the State of Illinois for all reasonable costs
including equipment, using the best current engineering practice
and scientific knowledge. If made by the State of Illinois, the
measurements and computations shall be conducted under the
continuous supervision and direction of the Corps of Engineers of
the United States Army in cooperation and consultation with the
United States Geological Survey, including but not limited to
periodic field investigation of measuring device calibration and
data gathering. All measurements and computations made by the State
of Illinois shall be subject to periodic audit by the Corps of
Engineers. An annual report on the measurements and computations
required by this decree shall be issued by the Corps of Engineers.
Best current engineering practice and scientific knowledge shall be
determined within six (6) months after implementation of the decree
based upon a recommendation from a majority of the members of a
three-member committee. The members of this committee shall be
appointed by the Chief of Engineers of the United States Army Corps
of Engineers. The members shall be selected on the basis of
recognized experience and technical expertise in flow measurement
or hydrology. None of the committee members shall be employees of
the Corps of Engineers or employees or paid consultants of any of
the parties to these proceedings other than
Page 449 U. S. 50
the United States. The Corps of Engineers shall convene such a
committee upon implementation of this decree and at least each five
(5) years after implementation of this decree to review and report
to the Corps of Engineers and the parties on the method of
accounting and the operation of the accounting procedure.
Reasonable notice of these meetings must be given to each of the
parties. Each party to these proceedings shall have the right to
attend committee meetings, inspect any and all measurement
facilities and structures, have access to any data and reports and
be permitted to take its own measurements.
B. Paragraph 5 of the said Decree entered by the Court herein is
amended by adding thereto an additional sentence to read as
follows:
The amendment to Paragraph 3 of this decree shall take effect on
the first day of October following the passage into law by the
General Assembly of the State of Illinois of an amendment to the
Level of Lake Michigan Act providing that the amount used for
dilution in the Sanitary and Ship Canal for water quality purposes
shall not be increased above three hundred twenty (320) cubic feet
per second, and that in allocations to new users of Lake Michigan
water, allocations for domestic purposes be given priority and to
the extent practicable allocations to new users of Lake Michigan
water shall be made with the goal of reducing withdrawals from the
Cambrian-Ordovician aquifer.
C. A certified copy of the above legislation shall be served
upon the parties and filed with the Clerk of the Supreme Court by
the State of Illinois. If no party raises an objection to the
adequacy of the legislation within 30 days of service, Illinois
will have complied with the requirements of the amendment made by
this Order to paragraph 5 of the Decree entered by the Court herein
on June 12, 1967. Any such objection shall be raised in the manner
set forth in Paragraph 7 of said Decree.
Page 449 U. S. 51
IT IS FURTHER. ORDERED THAT:
Each of the parties to this proceeding shall bear its own costs.
The expenses of the Special Master shall be borne by the State of
Illinois and the Metropolitan Sanitary District of Greater Chicago,
three-fifths thereof by the State of Illinois and two-fifths
thereof by the Metropolitan Sanitary District of Greater
Chicago.
JUSTICE MARSHALL took no part in the consideration or decision
of this order.
STATEMENT OF INTENT AND TECHNICAL BASIS FOR
PROPOSED AMENDMENTS TO 1967 DECREE
This statement sets forth the intent of the parties and the
technical basis for the revisions to certain of the provisions of
paragraphs 3 and 5 of the 1967 Decree.
The proposed change in the 1967 Decree has been designed to
alter in part the provisions of the existing Decree that prevent
Illinois from effectively utilizing and managing the 3200 cubic
feet per second (cfs) of Lake Michigan water which Illinois was
allocated.
Under the existing system, increasing amounts of impervious
areas and increasing demand by domestic users elevate the risk that
the language of the decree will be violated in any one or five year
period if additional allocations are made by the State to domestic
users for a period of years consistent with good management
practice.
The proposed change accomplishes the following:
"1. Increases the period for determining compliance with the
3200 cfs limit from a five year running average to a forty year
running average;"
"2. During the first thirty-nine years of the decree, allow
Illinois to exceed the 3200 cfs limit by 2000 cfs-years in the
aggregate (one cfs-year is the volume of water resulting from an
average flow of one cfs for a period of one year); "
Page 449 U. S. 52
"3. Limits the average diversion in any one accounting period to
115% of 3200 cfs, but in two years of any forty year period permits
the average diversion to reach 120% of 3200 cfs, to allow for
extreme hydrologic conditions."
The lengthening of the averaging period from five to forty years
reduces the variability of the averaged figure, thus decreasing the
amount of water that needs to be held in reserve for storm water
runoff and increasing the amount of water that may be allocated for
domestic purposes to reduce in part the pumpage from the
Cambrian-Ordovician aquifer.
The lengthening of the averaging period also allows an increase
in the planning period to a period of time that is more compatible
with the life of certain types of water supply facilities, thus
permitting more efficient use of the available diversion without
increasing the total allowable diversion, and permitting better
management of all the water resources of the region.
In establishing the limits of paragraph three of the amended
decree, the available data and uncertainties as to the behavior of
and interactions between the various elements of the hydrologic
regime under current and future conditions were limiting
factors.
To estimate maximum hydrologic variations that must be
considered in the allocation accounting process, the forty-four
year precipitation and runoff data contained in"Water Yield,
Urbanization, and the North Branch of the Chicago River," a report
by the Northeastern Illinois Planning Commission and Hydrocomp,
Inc., dated October 14, 1976, were used. These data assumed a 30%
imperviousness factor, and were used by the parties to approximate
the conditions of the entire Lake Michigan diversion watershed at
the present time.
These data indicate that the maximum departure above the mean
annual stormwater flow is 59%. Assuming, therefore,
Page 449 U. S. 53
that the mean annual stormwater flow is 683 cfs, the maximum
departure is 405 cfs. This could result in a diversion of 13% above
the allowable 3200 cfs maximum. Given the relatively short period
of record and the likelihood of increased runoff resulting from
urbanization, it was agreed that a 15% exceedance, to a maximum of
3680 cfs, would be allowed in any year to accommodate high
stormflows, and that, in any two years of the 40-year accounting
period, the diversion may be increased by 20%, to a maximum of 3840
cfs, to accommodate extraordinary hydrologic conditions.
Because of year-to-year variations in storm runoff, there will
be series of years when the average annual diversion will need to
exceed 3200 cfs for best management, and some years when the
diversion will be less than the 3200 cfs average. Calculations of
the cumulative sum of the annual departures show that the maximum
cumulative exceedance of 3200 cfs would be slightly below 1500
cfs-years as indicated by the forty-four years of data that were
used. The possibility exists that, in the initial forty-year
period, the cumulative exceedance may be greater than 1500
cfs-years. Since the record used is relatively short and
urbanization is likely to increase runoff, the maximum cumulative
exceedance has been established at 2000 cfs-years.
The goal of this amended Decree is to maintain the long-term
average annual diversion of water from Lake Michigan at or below
3200 cfs.
* Together with No. 2, Orig.,
Michigan v. Illinois et
al., and No. 3, Orig.,
New York v. Illinois et
al.
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