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:; United States Department of the Interior BUREAU OF LAND MANAGEMENT Crand Junction Resource Area 2815 H Road Grand Junction, Colorado 81506 JUN 2 7 2000 Dan Mathews Division of Minerals and Geology 2148 Broadway, #C-5 Grand Junction, Colorado 81503 Re: Powderhorn Coal Company Stream Crossings in Coal Canyon DMG Permit C-81-041 Dear Mr. Mathews: III IIIIIIIIIIIIIIII 999 1<AKE~~ ~ ~EI~N= .~ m~ ~ ~ ^ IN REPLY RFFER TO 3400 (CO-130) r~~~` ('~ ~~^ ~z~. ._ r,;:. ,_,.. ~~ ~~N 2 8 x1p0 J DIV. ~F MIIyERA GRA'NO ' ~S 6 G _ ~~NCrr~~°.f _. _ ~=r.. "_, , . Bruce Fowler, BLM Grand Junction Field Offtce Geologist, and Jim Scheidt, BLM Northwest Center Hydrologist, met with you in the field on June 15, 2000. The purpose of the field visit was to discuss the possible retention of culverts along the Coal Canyon road to better provide public access, and assess potential maintenance issues for BLM if the culverts were retained. In order to assess the current situation and evaluate issues with retaining the culverts, a reach of Coal Canyon was walked by Bruce and Jim. They started at the arched culverts, went up the channel over a series of four rock check dams, past the set of 36 inch culverts encased in concrete, to a reach of the channel where the natural stream sinuosity, channel slope, and channel cross sectional area could be observed. This upper reach was considerably different from the realigned section between [he culverts which includes [he check dams. The stream reach between the culverts, had a stair step profile due to dte check dams and the sediment detained behind the structures, had a wide flat channel bottom and tapered channel sides, had just one minor meander, showed areas where [he rocks used to construct [he checks had moved, some as far as the mouth of the arched culverts. The upper reach had a more gentle gradient, significantly higher sinuosity with typical cut banks on the outside of meanders, a narrower channel bed, and a terrace or floodplain along much of the alignment, BLM understands that following completion of mine reclamation, [he Division of Minerals and Geology (DMG) is recommending removal of the culverts and replacement with low water crossings. However, there is an option of retaining the culverts. The determination would be based on public access being better served by leaving the culverts in place, and BLM assuming future maintenance responsibilities. BLM is interested in keeping the culverts, but has a few concerns regarding the current hydrology in Coal Canyon. Although the canyon is generally dry, when convective storms pass through the area, the watershed is capable of producing significant runoff very quickly. These flashy events are capable of moving very large volumes of sediment,