Geneva Creek Iron Fen


Water FlowingLocated high in the Geneva Creek Basin, the Geneva Creek Iron Fens are registered as a Colorado State Natural Area. One of eight iron fens in the state, it is an example of both a rare community type and an unusual geologic process.

A fen is an area of peat-forming wetlands that receives nutrients usually from upslope mineral soils and groundwater movement. It is typically alkaline due to groundwater draining from surrounding calcareous rocks. Fens are different from bogs because bogs are acidic, not alkaline. Most fens have high pH's and have a high mineral content. Furthermore, bogs are rain fed and exist on the Canadian shield (Minnesota, Michigan, Maine, etc.), while fens are fed by groundwater.


Iron fens area a phenomenon unique to Colorado. There are eight iron fens documented in Colorado and no other known occurrences in the world. The iron fens, due to the iron substrate, are very low in pH (acid) and are high in minerals. The geologic process forming the iron fen begins with a series of springs flowing over highly fractured, highly mineralized bedrock rich in pyrites producing extremely acidic (pH3), mineral-rich water. This process produces limonite (iron saturated peat) ledges and terraces.

Rushing WaterAdoption

The Clear Creek County Open Space Commission acquired management of the Geneva Creek Iron Fen in the Spring of 2003. Much of the iron fen is located on two parcels that were former mining claims deeded back to the county for open space. After successfully lobbying to have the area preserved, the Geneva Creek Iron Fen was identified as and adopted into the

Geneva Creek Iron Fen.


Due to heavy off-highway-vehicle (OHV) use, the Geneva Creek Iron Fen and surrounding lands have experienced significant damage. In an effort to preserve and improve the fen, the Clear Creek County Open Space Commission is working with the South Platte Ranger District on developing and implementing a travel management plan. Therefore, if you visit the Iron Fen, please respect this significant natural area, and obey road closures and signs. However, because of its remote location, on the ground management is challenging, and it is possible that signs may be torn down. Therefore, please err on the side of caution, and do not cross Geneva Creek or leave designated roadways in your vehicle.

Colorado Natural Areas Program

Colorado Natural Areas Program with Colorado State Parks. Colorado Natural Areas preserve some of the finest examples of Colorado's original and unique landscapes for the benefit of present and future generations. Sites qualify as Colorado Natural Areas when they contain at least one unique or high-quality feature of statewide significance. Not only is the Geneva Creek Iron Fen considered one of the best examples of an iron fen in the state, but it also contains Colorado's only known occurrence of Girgensohn sphagnum moss.

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