Thursday, August 11, 2016

Decision Reached on Sprague Lake Dam Repair

The Director of the Intermountain Region, National Park Service (NPS), has signed a decision document that will enable the NPS Dam Safety Program to repair the Sprague Lake Dam in Rocky Mountain National Park. Although the dam is classified as having a Low Hazard Potential by the Federal Emergency Management Agency (FEMA), repairing the dam would help to protect park natural resources, cultural resources, and infrastructure such as trails, roads, and bridges in the event of a flood.

An Environmental Assessment (EA) was prepared to evaluate alternatives and the potential impacts associated with repairing the dam or maintaining the status quo.

The repairs to the Sprague Lake Dam consist of adding a seepage control berm, spillway improvements, slightly increasing the elevation of the dam crest in select locations, stump and tree removal from the dam, and construction of an inlet control structure that will limit flows into Sprague Lake to the capacity of the spillways. Flows greater than a 10-year flood will be diverted over Sprague Lake Road and conveyed via an existing drainage to Glacier Creek. The lake side of the dam will be armored with riprap to prevent erosion. Upon completion of the spillway improvements on the north side of the lake, a new pedestrian bridge will be constructed over the spillway.

A temporary access road will be constructed in the fall of 2016, to provide access to the dam. The dam repairs will be done in the fall of 2017. During the fall of 2017, portions of the accessible trail around Sprague Lake will be closed during the repair work.


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