2020-05-28_HYDROLOGY - M2001005

• Permit No: M2001005
• IBM Index Class Name: Hydrology
• Doc Date: 5/28/2020
• Doc Name: Substitute Water Supply Plan
• From: DWR
• To: Bishop-Brogden Associates, Inc.
• Email Name: TC1
• Media Type: D
• Archive: No

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May 28, 2020
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W = Distance between the Arkansas River and the alluvial boundary (feet)
The cumulative lagged depletions are 367.73 acre-feet for the 2020 plan year and 214.34 acre-feet
for the 2021 plan year, and may be found in Table 1, attached.
REPLACEMENTS
The main source of replacement water is based on the 81.4 acres that is now removed from
agricultural production by the mining operation out of the total pro rata share of 89.47 acres of
alfalfa and silage corn historically irrigated with Lester-Attebery Ditch water. A ditch wide analysis
has been completed and the calculated historical consumptive use for the Grisenti parcel was 220.8
acre-feet per year (2.47 acre-feet per acre). The historical irrigation summary is attached as Table
2. Although 89.4 acres are currently dried up, eight acres has been removed from the calculations
to account for potential future irrigation. The proposed dry-up of 81.4 acres of historically irrigated
land provides a historical consumptive use credit of 201.12 acre-feet (221.60 acre-feet credit
during April through October and a return flow obligation of 20.48 acre-feet during winter months).
Sixty shares of Twin Lakes Reservoir water will be used to supply the replacement water for the
winter months. Based on an average yield of 0.93 acre-feet per share, the Applicant can request
Twin Lakes release approximately 55.80 acre-feet per year. This water is subject to a 10.3 percent
transit loss (0.07% per mile for 147.8 miles) for delivery to the Grisenti site, yielding a replacement
supply of approximately 50 acre-feet per year.
The Applicant has one-time lease water for 2020 from the Pueblo Board of Water Works (PBWW)
stored in Pueblo Reservoir. Of the 150 acre-feet leased, 50 acre-feet is allocated to Grisenti Pit in
2020. Additionally, approximately 66.9 acre-feet is stored in CWPDA's account in Pueblo Reservoir.
This water was awarded from PBWW in a 2018 lease. The water remains available for use as it was
released from PBWW's account before the March 2019 deadline and stored in the indicated
reservoir. An additional lease for 2021 may be acquired from PBWW.
The Applicant will request an exchange from Twin Lakes or PBWW of approximately 166.61
acre-feet in the 2020 plan year and 54.20 acre-feet in the 2021 plan year. The proposed
replacement schedule for this SWSP's approval period is shown in attached Table 3.
LONG TERM AUGMENTATION
In accordance with the letter dated April 30, 2010 from the Colorado Division of Reclamation,
Mining, and Safety ("DRMS"), all sand and gravel mining operators must comply with the
requirements of the Colorado Reclamation Act and the Mineral Rules and Regulations for the
protection of water resources. The April 30, 2010 letter from DRMS requires that you provide
information to DRMS to demonstrate you can replace long term injurious stream depletions that
result from mining related exposure of groundwater. The DRMS letter identifies four approaches to
satisfy this requirement. Approach nos. 1 and 3 require bonding to ensure the pit can be backfilled
or lined. Approach no. 4 requires documentation to identify what water rights or other permanent
water source will be dedicated to the SWSP to assure that all permanent depletions from either an
unforeseen abandonment of the site by the Applicant or as a result of long term ground water
exposure after completion of mining and reclamation will be replaced so as to prevent injury to
other water rights.