WSP04556

• File Number: 8449.900
• Description: Bear Creek
• State: CO
• Basin: South Platte
• Date: 12/1/1991
• Author: Leonard Rice
• Title: Change of Pioneer Union and Hodgson Ditch Water Rights for Use at Fox Hollow Golf Course Cae 90CW185 - Supplemental Engineering Report
• Water Supply Pro - Doc Type: Publication

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Table 2
Average Annual (1938-1957) Ditch Diversions
acre-feet

Ditch

Total Ditch Diversions

Applicant's Diversions

Pioneer Union

2,881.8
581.7
3,463.5

524.8
47.3
572.1

Hodgson
Totals

11.3 Potential Crop Consumptive Use

Two commonly used methods for detennining potential crop consumptive use are the Modified
Blaney-Criddle method and the Jensen-Haise method. Though the Blaney-Criddle method is easy
to apply since it is based on historic mean daily temperatures and precipitation, it is generally
considered to provide consumptive use estimates that are significantly lower than values that
would be measured in the field without calibrated crop coefficients. The primary reason for
underestimating consumptive use is that the Blaney-Criddle method fails to consider high daytime
radiation that can occur even when mean daily temperatures are low.

The Jensen-Haise method uses a more detailed equation that considers temperature and solar
radiation, A major drawback in the application of this method is the lack of historic solar
radiation data in the vicinity of the served acreage, The Jensen-Haise method generally results
in higher consumptive use estimates than the Blaney-Criddle method,

Based on our research, and experience in other cases, we believe that a reasonable estimate of
potential consumptive use would be the average of results obtained from the Blaney-Criddle and
Jensen-Haise methods, The average of the two methods recognizes the Blaney-Criddle
underestimate of potential consumptive use and also the inclusion of a radiation term in the
analysis.

Analysis of both methods with climatic data from the Denver WSFO AP Station, approximately
16 miles northeast of the acreage served by the subject water rights, indicates that the Jensen-
Haise method provides results approximately 40 percent greater than the Blaney-Criddle method
for the 1951-1980 period, Based on an average of the two methods, we have adopted a potential
crop consumptive use of 120 percent of the Blaney-Criddle results using the Edgewater climate
station data for the study period 1938-1957. This station is approximately 8 miles northeast of
the acreage served by the subject water rights.

Table 3 provides a summary of the potential consumptive use of irrigation water by the various
historic crops. Monthly results of the multiplication product of the potential crop consumptive
use and the served acreages are shown in Tables A-3 and A-4 (Appendix A) for the subject water

3

~ Leonard Rice Consulllng Water Engineers, Inc.