WSP12637

• File Number: 8282.300
• Description: Colorado River Operations and Accounting - Lower Basin Administrative Procedures
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 8/1/1996
• Author: DOI-BOR
• Title: Description and Assessment of Operations-Maintenance and Sensitive Species of the Lower Colorado River - Volume I - Report - 08-01-96
• Water Supply Pro - Doc Type: Report/Study

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d. Seasonal Release Patterns

There are four seasonal release patterns for the three facilities - Hoover Dam, Davis Dam,
and Parker Dam. Figures 18, 19, and 20, respectively, show the Hoover, Davis and
Parker Dams' normal hourly release pattern for a representative day in each of the four
seasons. The curves show a flatter water release for Parker Dam than for Davis Dam; with
Hoover Dam releases taking most of the fluctuations. This is due to the fact that
Hoover Dam normally releases water directly into Lake Mohave, which serves to stabilize
river fluctuations. Hoover Dam is used to respond to power system fluctuations because it
responds quicker, more efficiently, and with the least disturbance to the river system.

6. River Maintenance

Under the authority of the CRFWLS Act of March 3, 1925, as amended, Reclamation
maintains the channel, banklines, levee systems, and control structures along the lower
Colorado River. This includes 168 miles of stabilized banklines, 114 miles of levees and
75 associated river structures including jetties and training structures. For administrative
purposes the reaches of the river from Davis Dam to the SIB are divided into maintenance
divisions, which are roughly determined by different physical characteristics as identified in
Figure 2. A description of each division is presented in Appendix C.

The routine maintenance on existing stabilized banklines consists of placing riprap on
bankline areas where the existing riprap has eroded or otherwise needs repair. Other routine
maintenance involving riprap includes repair of jetties and training structures. Again, this
repair consists of replacing riprap where it has eroded or otherwise needs replacing. Some
riprap is needed occasionally for repair of levee armoring.

Associated with the maintenance of the banklines, levees, and river control structures is
maintenance of access and bankline roads. Roads are maintained on the levees and adjacent
areas to stabilize banklines. The maintenance is routine road repair required for gravel
roads. While these roads are also used by the public for various reasons, the roads are
maintained for operation and maintenance of Reclamation project facilities and are not
maintained up to public road standards.

Riprap and gravel for the above maintenance activities are obtained from various stockpile
sites located along the river if the work is conducted by Reclamation personnel. As a rule,
quarrying activities are conducted to produce and maintain stockpiles of rock and gravel
along the river for emergency flood control purposes and routine maintenance described
above. In general, quarrying and hauling activities are contracted when it is determined the
stockpiles need to be replenished. This replenishment could be necessary after a long period
of time if the stockpiles are used only for routine maintenance, or after a short period of time
if a high-flow emergency occurs. In some cases, if extensive repairs are required to stabilize
banklines, levees, and river control structures, the work is contracted to private enterprise.
In many of those cases, quarrying activities occur and the riprap and gravel are hauled
directly from the quarry.

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