GENERAL48692

• Permit No: C1981019
• IBM Index Class Name: General Documents
• Doc Name: Proposed Decision & Findings of Compliance
• Permit Index Doc Type: General Correspondence
• Media Type: D
• Archive: No

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VII. Alluvial Valleu Floors - Rules 2.06.8 aryl 4.24
No alluvial valley floors (A VF's) exist within the area to be mined.
However,. several Small AVF's do exist Within the proposed permit area and
adjacent areas. The alluvial deposits of Good Spring Creek, Wilson Creek;.
and lower Elkhorn Creek meet the geomorphic criteria and irrigation
requirements of an AVF, as outlined in OSM's "Alluvial Valley Floor
Guidelines" established pursuant to the Surface Mining Control and
Reclamation Act of 1977. Taylor Creek was determined not to be an AVF
because of insufficient water availability to support irrigated
agricultural activities. Information subnittm' by the applicant by
letter on October 8, 1981, shows that it is not the regional practice
to irrigate crops along drainages of similar size and yielding similar
amounts of water as Taylor Creek.
Pursuant to Rule 2.04.8, the Division is required to make specific written
findings on the effect of mining on all AVF 's within the permit and
adjacent area: Findings Pursuant to Rule 2.06.8 (5)(a)(i)(A)(I) regarding
interruption, discontinuance, or preclusion of farming and Rule 2.06.8
(5)(a)(i)(A)(II) regarding material damage to water quality and quantity
supplied to the AVF cannot be applia3 to the Colowyo operation. The __ __ _
proposed permit area was included in Open Mining Permit No. 76-15 issued by the
Mined Land Reclamation Board, on August 31, 1976 and is thus excluded from
the above requirements as specified by Rale 2.06.8(5)(a)(i)(B). The
finding specified by Rule 2. 06.8 (5)(a)(i)(a)(ISI) regarding preservation
of the essential hydrologic functions of the alluvial valley floor is
required. The findings for each of the alluvial valley floors identified
in the mine area are presented separately below. Since no AVF 's exist
within the area to be mined, the applicant does not propose to physically
disturb any AVF's. Any mining related impacts that could occur are
secondary in nature. T1-.at is, there is the potential for the quality
of water that flows into the RVF's to be slightly degraded as a result of
mining. This impact is not expected to be significant as discussed in
the following analysis.
GOOD SPRING CREEK
The alluvial deposits along Good Spring Creek constitute an AVF because
therea<'ze enough unconsolidat~ stream-laid deposits and sufficient
water yield to be beneficial for crop irrigaiton. There is both historical
and existing flood irzigation being practiced on the AVF. Map 10 of
the permit application delineates the boundaries of the AVF and shows
existing irrigated lands.
The applicant has presented land use information on Map 17 of the permit
application. Land use along the Good Spring Creek AVF consists of
cropland, pasture, and undeveloped rangeland. Irrigated native hay is
produced by several farms in the adjacent area. The applicant has
determined that productivity of this irrigated hayland averages 3°tons
per acre per year. This productivity value indicates that the crop yield
is probably being enhanced by the irrigation activities. Based upon the
Division's investigation and information provided by the applicant, the
Division makes the following finding.