Here is an update on work occurring at Mark Twain National Forest’s Crane Lake, a 100-acre fishing lake in Iron County.
A contract was awarded to Meramec Excavating to construct an emergency access road to Crane Lake’s dam and a temporary boat ramp. Work has been progressing on both projects.
Historically, there has been limited access to Crane Lake dam due to its remote location. We have been using Forest Road 2115 to access the dam for years, but damaged concrete culverts on this road has further limited administrative access to lightweight vehicles such as utility task vehicles. Part of the Crane Lake National Recreation Trail travels on Forest Road 2115.
We looked at alternative access routes to the dam with an important consideration in mind – emergency heavy equipment must be able to use the access route during a high water event. Many people have asked me “why not repair the culverts on Forest Road 2115?” Our hydrologic and hydraulic modeling show that sections of Forest Road 2115 could be inundated with lake water if a serious precipitation event were to occur, which then would limit emergency access.
The new access road will be an extension of Forest Road 2113. It will be used only for administrative access to the dam, and because of this, a gate will be installed where the new section of road takes off from the existing Forest Road 2113. Once this is complete, Forest Road 2115 will be decommissioned and we will work with trail user groups to rehabilitate and improve this section of Crane Lake National Recreation Trail for hiking, mountain biking, and equestrian use.
The partial drawdown of Crane Lake that has been necessary to address hydrologic and structural deficiencies in the dam will continue into the future. Boat access to the lake has been affected by the drawdown, but construction of the temporary boat ramp will enable anglers and boaters to access the lake when water levels are down. The contractor has built the short access road to the temporary ramp. Articulated concrete matting and rock will be delivered in the next month, which will provide firm surfaces for launching watercraft.
Other work is taking place at Crane Lake. Forest Service crews have been working to remove two tree trunks and woody debris from the dam’s outlet structure over the past couple weeks. Once cleared, the partial drawdown will lower water levels by 8-12 feet.
A crew from the U. S. Geological Survey has also been out to the lake to survey the dam and appurtenances. Survey data will provide a baseline to monitor the cracks and other concrete deficiencies, but will also provide design level survey data for the future design work. Their work will include a combination of standard survey methods and ground-based LiDAR (light detection and ranging).
A scope of work is being prepared for an engineering firm to finalize alternatives for addressing the dam’s deficiencies. The scope of work will likely include an optional bid item to complete an engineering design on the preferred alternative, once chosen. It is our intent to share alternatives with the public when that phase of the scope of work is completed. We will use these alternatives for the environmental analysis required by the National Environmental Policy Act.
The Potosi Ranger Station is open Monday-Friday, 8 a.m. to 4:30 p.m. You can reach us by calling 573-438-5427. To receive updates on Mark Twain National Forest events and happenings, follow us on Twitter @marktwain_nf, and like us on our Facebook page, www.facebook.com/marktwainnationalforest.
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