2012-02-02_HYDROLOGY - M1977439

• Permit No: M1977439
• IBM Index Class Name: HYDROLOGY
• Doc Date: 2/2/2012
• Doc Name: SWSP
• From: OSE
• To: Tri-Districts
• Permit Index Doc Type: Hydrology Report
• Email Name: ECS
• Media Type: D
• Archive: No

Unlined Lake
Surface Area
(acres)
Centroid Distance
(feet)
Evaporative Loss
(acre -feet)
Treiber A
37.6
630
145.30
Treiber B
25.6
640
Lamb A
22.1
Pre -81 Exposed Area
Lamb B
42.4
956
141.19
Lamb C
19.4
750
Richard T. Rains, P.H.
Partners Home Office SWSP
February 2, 2012
reservoirs in water court case no. 2000CW251. Additionally, DRMS Permit No. M- 2011 -049
has been applied for by the Partners to allow for slurry wall construction at the Treiber ponds.
This future construction activity is not included in this SWSP approval.
Depletions
Net evaporative depletions were calculated using a gross annual evaporation of 38
inches from the exposed water surface, with a credit of 10.5 inches for effective precipitation.
Based on an aerial photo taken in 2009, the total exposed surface area at this site is 147.1
acres. According to the information submitted, 22.1 acres of water surface was exposed within
the reclamation permit boundary prior to January 1, 1981. This results in 125 acres of exposed
surface area requiring replacement of depletions from evaporation (See Tables 1 & 2). The
anticipated net depletion for this plan is 286.5 acre -feet per year for 125 acres of ground water
exposed after December 31, 1980. No phreatophyte credit has been applied to this plan.
The Applicant did not assume any specific periods of ice coverage for the purposes of
projecting the evaporative depletions requiring replacement. However, the Applicant retains the
ability to track actual "ice covered" days and reduce the amount of evaporative losses that need
to be replaced. Computation of the net evaporation during months with ice covered days shall
be determined as the pro -rata amount of the monthly gross evaporation rate distribution amount
identified in the State Engineer's General Guidelines for Substitute Supply Plans for Sand and
Gravel Pits, subtracting the pro -rata amount of the effective precipitation for that period. Lagged
depletions hitting the river during ice covered days require replacement.
The monthly depletions to the Cache la Poudre River were lagged from the pit site using
the AWAS program developed by the IDS Group at Colorado State University. The parameters
used in the model were an estimated distance from the exposed water surface area to the river
(X) of 744 feet (representing the average distance from the centroid to the river), an estimated
distance from the site to the no flow aquifer boundary (W, measured perpendicular to the point
of impact) of 6,500 feet, an aquifer transmissivity (T) of 160,000 gallons per day per foot, and a
specific yield (S) of 0.2. The lagged stream depletions have reached steady state conditions
and are estimated to total 286.5 acre -feet during the term of this approval, with a monthly
distribution shown on the attached Table 3.
TABLE A — DEPLETION SUMMARY
Total Loss
Page 2 of 5
Replacement
The proposed sources of replacement are various supplies owned by the City of Greeley
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