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GPCD values used for these enitities are included in the detailed description of filling missing <br />records in Appendix A. <br />Water use by one entity, NCWA, was estimated for unknown years from information submitted <br />verbally by the user. NCWA indicated that pumping started on a certain date and increased by <br />a fixed percent each year for the unknown years. <br />In cases when a regression equation could not be developed, one of the following methods was <br />used to estimate data for the missing years: <br />• Estimate water usage using daily per capita water usage and population data. <br />• Average existing data into annual amounts and then use this to estimate long -term <br />averages. Use average value for missing years and distribute back into monthly <br />pumping using the monthly patterns present in the data provided. <br />• Calculate the ratio of actual pumping to estimated pumping from population data and <br />GPCD value for years common to both sets of records. <br />• Evaluate trends using linear or non - linear regression analyses. If no trend or ratio is <br />available use earliest data and apply to previous years. <br />• For industrial/ commercial entities, if no data were provided, use the decreed pumping <br />rate as a constant pumping rate and the appropriation date as the starting date. <br />From these analyses an annual total pumping rate was estimated for the missing years. To <br />disaggregate these values into individual well rates, the pumping data from individual wells <br />was used to calculate the percentage of pumping for each individual well. This percentage was <br />applied to estimate annual pumping values from individual wells for the years when data were <br />not provided. <br />To estimate monthly pumping, as required for this task, the percentage of the total annual <br />pumping from each month was estimated for each entity based on reported monthly data and <br />applied to estimated annual pumping rates for the missing years. This approach was used to <br />simplify the calculations and was based on the assumption that the percentage of monthly <br />pumping was similar in all individual wells. For data with no monthly records, monthly <br />percentage values were used from other nearby entities that had a similar well use type. An <br />example of a monthly distribution of pumping is provided in Figure 1, below for Ft Lupton. <br />This Figure shows that pumping reaches a maximum value in late summer, due to increased <br />demands associated with outdoor watering. <br />SPDSS Phase 3 Task 41 TM -Final <br />02/08/2007 <br />E <br />