2025-12-12_HYDROLOGY - M1977023

• Permit No: M1977023
• IBM Index Class Name: Hydrology
• Doc Date: 12/12/2025
• Doc Name: Substitute Water Supply Plan
• From: Division of Water Resources
• To: DRMS
• Email Name: DMC
• Email Name: THM
• Media Type: D
• Archive: No

Peter Foster and Jonah Howe, Wright Water Engineers Page 12 of 14
Re: Gunnison West Gravel Pit SWSP, Amendment No. 1
December 12, 2025
groundwater on the dried-up land. The Applicant shall modify its accounting to reduce
the amount of the calculated HCU that may be claimed in this SWSP according to the
table below. Measurements taken at the start of each month will determine the
necessary reduction in credit to be applied during the following month. The Applicant
may use another methodology upon review and prior approval by the State Engineer
and Division Engineer. (Construction of monitoring holes/wells, or piezometers
requires that permits or notices be obtained as described in Table 1 of the Water Well
Construction Rules.)
Depth to Percent Reduction in Calculated HCU'
Groundwater (Feet) Native Grass Alfalfa
1 85% 100%
2 50% 90%
3 30% 75%
4 20% 50%
5 15% 35%
6 10% 20%
7 5% 15%
8 0% 10%
14. 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 (attached) from DRMS requires that the Applicant provide
information to DRMS to demonstrate the Applicant can replace long term
injurious stream depletions that result from mining-related exposure of
groundwater.
In accordance with approach no. 4, the Applicant has previously provided a
1 Adapted from Evapotranspiration and Agronomic Responses in Formerly Irrigated Mountain
Meadows, South Park, Colorado, March 1, 1990; Revised September 1, 1991.