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Slide 1
This chart illustrates a very basic schematic to the streamflow model. The following items are of note:

• The upper region and lower regions in accordance with the administration of the Bear River and the Compact. The regions are split at Pixley Dam.

• Three gages have been identified as very important to the streamflow model. These locations are (1) inflow into Wyoming at Gage 11500, (2) inflows into Utah at Gage 20300, and (3) inflows to Idaho at Gage 39500.

• The operational criteria of three reservoirs are also important in the streamflow model: (a) Sulfur Creek Reservoir; (b) Woodruff Narrows Reservoir; and (c) Whitman Reservoir in Utah.

• Inflows from tributaries will be integrated to the extent that streamflow and diversion records are available (i.e., Smiths Fork).

This schematic will be much more detailed as work progresses with additional gages, diversion locations, return flow locations, and inflows from the tributaries, etc.

The methodology utilized to determine the average, wet and dry years involves plotting the average annual flows for the three earmarked gages previously discussed (Gages 11500, 20300 and 39500) for the period of record from 1971 to 1998. The 20th percentile is proposed to be used as the cutoff for identification of the wet and dry years. This means that five years have been initially identified as dry years and five years have been initially identified as wet years.

Based on the data, there were three consistently wet and dry years that stood out in both the upper and lower regions (1977, 1992 and 1994 for the dry years and 1983, 1984 and 1986 for the wet years). In summary the preliminary chosen wet and dry years are indicated below and on the chart

		Wet:	1972		Dry:	1977
			1983			1979
			1984			1990
	 		1986			1992
			1995			1994

The determination of the study period was based on the available streamflow and diversion data/records. Based on the review of available data, and input from the BAG, a 28-year study period was selected from 1971 to 1998. This chart illustrates the period of record for several streamflow gages within the Bear River Basin. Records associated with items 3, 15 and 25 which reflect the gages noted above (Gage 11500, 20300, and 39500 respectively). These gages all have continuous records within the selected study period. Several of the main stem gages will be utilized as calibration gages for the model development (to verify assumptions made to simplify the model). Where records are not continuous, analytical procedures will be utilized to create a continuous data set.

The diversion records were also reviewed and evaluated. Complete and continuous diversion data were available for all years beginning with 1971. This was another reason that the study period was selected from 1971 to 1995. Item number 27 in the chart reflects the diversion data.

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