BOARD00158

• Board Meeting Date: 12/12/1973
• Description: Agenda or Table of Contents, Minutes, Memos
• Board Meetings - Doc Type: Meeting

Some explanation of the salinity standards is in order. In the first
place, the word, "salinity" is misleading in that the actual criteria
is not salinity per se, but total dissolved solids, which means that
the so-called salinity standards include a wide variety of various
chemical compounds. To the average person, salinity means salt that I
we use in everyday life, that is, sodium chloride. Yesterday I
received a letter from a lady stating that in her opinion most of
the salinity came from salt being put on the highways by the State
Highway Department. That does contribute some to the salinity of
the various rivers, but is not a significant amount in terms of total
dissolved solids which are carried in the Colorado River.

The principal constituent of total dissolved solids in the Colorado
River is not salt in the normal sense, that is, sodium chloride. The
principal constituents are calcium compounds; namely, calcium car-
bonate and calcium sulfate, with calcium carbonate being the pre-
dominant of all the chemical compounds which occur in the Colorado
River.

I will recite some background as far as the agreement with Mexico is
concerned and what it means. In 1961, the Well ton-Mohawk project,
a division of the Gila project in Arizona, began operation. From
that project, which is a Bureau of reclamation project, considerable
amoUnts of saline water were pumped from the ground under the Wellton-
Mohawk project, which is near Yuma, Arizona. That water was dis-
charged into the Colorado River above the international boundary. The
purpose of that pumping was to get rid of the highly saline waters
under the Well ton-Mohawk lands and to replace those waters with water
of a better quality from the Colorado River. This started the prob-
lem with Mexico because the water coming from that project was about
5,000 parts per million, and did create some problems in Mexico.

That started negotiations between the United States and Mexico leading
to the agreement contained in the Minute 242 executed in Mexico City
on August 30, 1973. By that agreement, the United States agreed
that by not later than July 1, 1974, the United States will adopt
appropriate measures to insure that the waters of the Colorado River
delivered to Mexico shall not contain an annual salinity of more I
than 115 parts per million over that water which arrives at Imperial
Dam. The Minute 242 or the proposed regulation of the EPA does not
define the quality at Imperial Dam. However, from public statements
made by Mexican officials, they assume that the agreed upon figure
'was not to exceed 865 parts per million. That is the understanding
upon which Mexico executed the agreement.

This simply means that between Imperial Darn near Yuma and delivery at
the international boundary the salinity of the river can increase by

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