BOARD00223

• Board Meeting Date: 9/13/2004
• Description: ISF Section - Proposed Water Right Donation - Colorado Water Trust, Peabody #1 Ditch and Lund Enlargement, Boulder Creek and Blue River
• Board Meetings - Doc Type: Memo

779.3 ac- ft. Max diversions were 1070.1 ac- ft/yr for the senior right and 406.1 ac- ft/yr for the
junior right.

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Anne Janicki
Page 2
August 25, 2004

2. Irrigated Acreage - We measured 63 acres for the historic irrigated area under the Peabody
No.1 Ditch using a pre-l 994 (exact date unknown) color aerial photo and interviews with the
original owners at the time of our last report. The water commissioner also measured a
historic irrigated area of63 acres as reported to us in a phone conversation in 1994. We used
this acreage for the period from 1904 though 1990. After 1990, some of the acreage was taken
out of irrigation. The current acreage recorded by the State under the Peabody No. I Ditch
is 42 acres, which is what we used for 1991 through 1999. No irrigation has occurred since
1999. In our previous report, we had rounded down the acreage to 60 acres for the 1970 to
1990 period.

3. Crop Irrigation Requirement - The CIR used previously was 1.45 ac-ft/ac which was
decreed in the Town of Breckenridge decrees for the Clayton Hills Ranch and was appropriate
for our original analysis. However, for this analysis, we used the Blaney-Criddle method to
calculate a more specific CIR for the parcel. We used Dillon Reservoir climate data
(temperature and precipitation) for the 1965 to 2002 period, and specific high altitude pasture
grass crop coefficients developed by the Denver Water Department and reported in
Evauotransuiration in High Altitude Mountain Meadows in Grand County. Our calculations
show an average CIR of 1.26 ac- ft/ac as shown in Table 4, slightly lower than the 1.45 ac-ft/ac
used previously. For the entire 63 acres, the average annual CIR is about 79.4 ac- ft, or 7.6 ac-
ft less than the 87 ac~ft in our previous report.

4. Water BudgetInputs - For the inputs for this depletion analysis, we used the same ditch loss,
maximum irrigation efficiency and return flow assumptions as we used in our previous
analysis. Ditch loss was 15%, maximum irrigation efficiency was 50%, and all surface water
and ground water return flows are assumed to reach the stream during the month of diversion.
We ran the analysis on a monthly basis for each of the years in the 1965 to 2002 period. We
also expanded the depletion tables as we did the diversion tables to cover the 1904 to 2003
period, as shown in Table 5. In addition, we ran an independent depletion analysis for the
senior right to determine what portion of the depletions were attributable to the senior right.

5. Results - We found that the diversions under the senior right were enough to completely
satisfy the CIR each year, therefore, the CD table for the senior right is identical to Table 5.
No depletions were attributable to the junior right. For the entire 1904 to 2003 period,
depletions averaged 73 ac-ft/yr. This is less than the 87 ac-ft/yr from the previous analysis
(1970 to 1990) due to the revised CIR value and study period, including recent years with
reduced irrigation and four years with no irrigation. The maximum annual depletion was 97.5
ac- ft in 1972.

6. Summary - Based on the results of this analysis, we have prepared Table 6 which shows the
monthly and annual proposed volumetric limits (in acre feet and cubic feet per second) for
,
each of the water rights. As shown, the average annual diversions for the senior right are
707.8 ac-ft, with a maximum of 1070.1 ac-ft/yr. The average annual CD for the senior right