WSP09796

• File Number: 8220.200.06.M
• Description: Imperial Dam
• Basin: Colorado Mainstem
• Date: 1/1/1981
• Author: USDOI/BOR
• Title: Regional Director's Report of Flows and Diversions at Imperial Dam and All Actions Affecting the Coordination Thereof - Calendar Year 1981
• Water Supply Pro - Doc Type: Annual Report

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10. Sediment and Quality of Water Determinations

c

Water quality samples are
Imperial Dam by Reclamation
shown on Table No.6,

taken in
personnel,

the river immediately above
Results of these samples are

The sediment sampling program as revised by the Regional Director in
his letter of March 16, 1960, continued throughout the year.

Listed below are the sampling stations and the frequency of sampling
now in effect.

Yuma Main Canal below Siphon Drop

2 times each month

Gila Gravity Main Canal, Station 114+50

2 times each month

California Sluiceway

2 times each month

Generally, when sampling is scheduled in the California Sluiceway,
the sluiceway gates are closed and the only flow in the sluiceway
at the sampling station is the leakage through the gates. The
velocity is so low that an accurate sample cannot be obtained.

Based on provisional data, 494,000 tons of suspended sediment were
returned to the river by the All-American Canal Desilting Basin sludge
pipes during calendar year 1981. The measured suspended sediment load
passing Imperial Dam for calendar year 1981 was 714,000 tons. Table
No. 5 shows monthly quantities of sediment returned to the river and
passing Imperial Dam.

11. Laguna Dam

During January, flows up to 2,380 cfs passed Laguna Dam as a result of
anticipatory releases from Hoover Dam. During the remainder of the
year, flows returned to normal and were coordinated with operations at
Imperial Dam and Senator Wash.

Laguna Reservoir is operated as necessary to provide stored water to
meet irrigation requirements and to facilitate sluicing operations at
Imperial Dam. Water stored in Laguna Reservoir has proved extremely
valuable in supplementing the flow arriving at Imperial Dam when the
demand for water is greater than the amount ordered on the master
schedule, or when the flow above the dam is below the amount ordered.
Storage available in Laguns Reservoir has proven valuable in
avoiding over deliveries to Mexico.

In order to move sediment deposits from the California Sluiceway
down river to the Laguna Settling Basin between Imperial and
Laguna Dam, it has been necessary to frequently drain and refill
Laguna Reservoir. This is accomplished by intermittently releasing
water stored in the reservoir in satisfaction of Mexico's daily

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