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Pinal AMA Surface Water Conditions

Streamflow data, including average seasonal flow, annual flow and other information are shown in Table 8.2-2.  Flood ALERT equipment in the AMA is shown in Table 8.2-3.  Flood ALERT equipment information is current up to October 2005.  New flood warning gages are routinely added to the ALERT network so the current number of stations may be greater.  Reservoir and stockpond data, including maximum storage or maximum surface area, are shown in Table 8.2-4. The location of streamflow gages identified by USGS number, flood ALERT equipment, USGS runoff contours and large reservoirs are shown on Figure 8.2-4.   Descriptions of stream, reservoir and stockpond data sources and methods are found in Volume 1, Appendix A.

Streamflow Data

  • Refer to Table 8.2-2.
  • Data from nine stations located at five watercourses are shown in the table and on Figure 8.2-4
  • Average seasonal flow at the Gila River gages is highest during the winter season (January-March) and highest on other watercourses during the summer (July-September). 
  • The largest annual flow recorded in the AMA is 1.2 million acre feet (maf) in 1993 at the Gila River near Laveen gage with a contributing drainage area of 20,615 square miles. 

Flood ALERT Equipment

  • Refer to Table 8.2-3.
  • There are 10 ALERT gages in the Pinal AMA.

Reservoirs and Stockponds

  • Refer to Table 8.2-4.
  • The AMA contains three large reservoirs.  The largest, Saint Clair, has a maximum storage of 375,000 acre-feet, but currently there is no infrastructure to fill it.
  • Reservoirs uses vary and include recreation, flood control, irrigation, fish and wildlife, fire protection, stock or farm, and water supply.
  • Water is diverted for the San Carlos Irrigation Project (SCIP) at Ashurst-Hayden Diversion Dam located on the Gila River 12 miles east of Florence.  The dam, completed in 1922, consists of diversion works and is not a storage or flood control facility.
  • Surface water is stored or could be stored in 12 small reservoirs. 
  • There are 315 registered stockponds in the AMA.

Runoff Contour

  • Refer to Figure 8.2-4.
  • Average annual runoff is highest, 0.5 inches per year or 26.7 acre-feet per square mile, at the northeastern tip of the AMA and the southwestern portion of the AMA and decreases to 0.1 inches, or five acre-feet per square mile, in the center of the AMA.

Click to view Table 8.2-2

Table 8.2-2 Streamflow Data for the Pinal AMA

Click to view Table 8.2-3

Table 8.2-3 Flood ALERT Equipment in the Pinal AMA

Click to view Table 8.2-4

Table 8.2-4 Reservoirs and Stockponds in the Pinal AMA

Click to view Figure 8.2-4

Figure 8.2-4 Pinal AMA Surface Water Conditions



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