WMOD00104

• Applicant: North American Weather Consultants, Inc.
• Sponsor Name: Denver Water
• Project Name: Cloud Seeding Evaluation
• Title: Development of Traget/Control Evaluation Procedures For the Denver Board of Water Commissioners Winter Snowpack Enhancement Project
• Prepared For: Denver Water
• Prepared By: NAWC
• Date: 12/31/2002
• County: Summit
• County: Clear Creek
• Weather Modification - Doc Type: Report

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4. Results for the Overall Denver Water Project Area

Linear regression fitting techniques were used to determine the best
combinations of data sites in the snowpack and precipitation data analyses. However,
in each case, for the same control sites, the results using a non-linear fit are also
shown. All the results in this section of the report pertain to the entire Denver Water
target area. Table 3 contains a complete, numbered list of all the target and control
sites in the final selection, for use with the maps in the following sub-sections. To avoid
confusion, it is worth noting that some of these sites were used in both the snowpack
and precipitation analysis.

TABLE 3.
List of all Target and Control Sites for Map Identification

Target:
1. Antera
2, Arrow
3. Berthoud Falls
4. Berthoud Pass
5. Berthoud Summit
6. Blue River
7. Como
8. Copper Mountain
9, Empire
10. Fremont Pass
11. Geneva Park

12. Grizzly Peak
13, Hoosier Pass
14, Horseshoe Mtn
15. Jones Pass
16. Lapland
17. Middle Fork CG
18. Mosquito Creek
19. Ranch Creek
20. Shrine Pass
21. Snake River
22. Summit Ranch

Snowpack Analysis

23. Vasquez

32. Gore Pass
33. Grand Junction
34. Hamilton
35. Hayden
36. Lasal Mtn, UT
37. Lynx Pass
38. Rabbit Ears
39. Yampa View

Control:
24. Arches NP, UT
25. Brown Cabin
26. Burro Mtn Tel
27. Columbine Tel
28. Crosho
29. Deadman Hill Tel
30, Dry Lake Tel
31. Elk River Tel

The best results of numerous snowpack data linear regression trials and
analyses are presented in Table 4. Linear and polynomial results are shown. In Table
4, the data types shown in bold type are used for this specific analysis. These results
are based upon twenty-two target area sites and nine control sites in three control
areas (see Figures 4a and 4b) for an historic base period of twenty-one seasons within
a thirty-one year period. The plotted data pairs and curve fits for the snowpack
analyses are shown in Figures 5a and 5b.

It is worth noting here inherent limitations of using the April 1 snapshot
measurements based upon snowcourses and snow pillows to represent the winter
snowpack water equivalent. These limitations are due to timing issues. For example,
significant snow could potentially accumulate prior to the start of seeding. Also, the
April 1 snowcourse measurement (manual snow survey) may not occur on the first day
of the month. In reality. storminess or other logistical factors frequently result in the
survey being conducted sometime within a ten day period bracketing April 1. Thus

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