Death Of a Lake

[awhuber]

Public Scoping Period for Crane Lake Dam Project is Open
Mark Twain National Forest hosted an informational open house on September 26th at Arcadia Academy, in Iron County, Missouri. Attendees were provided an update on Crane Lake, which included the unveiling of feasible alternatives that could address the dam’s deficiencies.
The open house launched the official environmental planning effort for the Crane Lake High Hazard Dam Safety and Compliance Project.
Crane Lake is a 100-acre lake located in Iron County, on the Potosi-Fredericktown Ranger District. Engineering inspections and studies carried out over the past four years have found numerous deficiencies in Crane Lake’s dam. It cannot pass 100% of the probable maximum flood, a requirement for all federal dams in the high hazard category. Furthermore there are structural deficiencies, as well as seismic concerns.
Feasible alternatives to address the federal safety concerns were developed by an engineering firm with expertise in dams. The Forest Service compared and contrasted the alternatives based on criteria such as cost and how well each addresses ecosystem health and resiliency, socioeconomic and recreational benefits, and downstream public safety. The alternatives varied from full decommissioning of the dam with restoration of the lake bed to full reconstruction of the dam, with several alternatives calling for some modification of the dam.
Forest Supervisor Sherri Schwenke identified two alternatives to carry through the National Environmental Policy Act (NEPA) planning process. The NEPA planning process must be completed in order to move the project through completion of the engineering design stage and then to actual on-the-ground work.
One alternative being carried forward is the Forest Supervisor’s proposed action, “Alternative E, Armor the Earthen Embankment with Roller-Compacted Concrete and Buttress the Spillways.” This alternative would correct the hydrologic, hydraulic, structural and seismic deficiencies in the dam using the footprint of the existing structure; it can be phased in the event only partial funding could be acquired; it will maintain the largest lake possible at around 100-105 acres; and it will help maintain an ecological block on Crane Pond Creek which will help protect a rare crayfish population from an invasive species. Projected costs over a 50-year time period were more economical than other alternatives - an estimated $3.5 million would be needed for construction, while it would have minimal annual maintenance requirements.
The second alternative to be included in the NEPA planning process is “Alternative I, Full Decommissioning with Restoration of the Lake Bed and Crane Pond Creek.” Supervisor Schwenke wants to conduct further analysis on this alternative because there is agency interest in reducing deferred maintenance backlogs nationally. Removing the dam and restoring the lake bed and stream would cost much less than any of the alternatives calling for modifications of the dam.
The first step in the NEPA planning process is a 30-day public scoping period. Comments about the alternatives will help the Forest Supervisor understand what issues to focus on during the environmental analysis, or if there is any new information to consider.
The open house attendees were able to discuss the alternatives with Forest Service employees and were invited to leave any comments they had. Comments can be provided through October 31, 2019. To receive a packet of information about the project, or to share a comment, please send an email to comments-eastern-mark-twain@usda.gov. You may also request an information packet by calling the Potosi Ranger Station at (573) 438-5427.
Once public scoping is completed, Forest Service resource specialists will conduct an environmental analysis. Upon completion of that, an environmental assessment will be compiled and made available for a 30-day comment period. Completion of the planning process often takes up to a year, but can vary based on the number of comments received or the environmental consequences identified.

 

[jdmidwest]

https://www.riverhillstraveler.com/removing-the-dam-restoring-the-stream-is-one-alternative-for-crane-lake/