Emergence Setting and Hydrology

Helocrene spring, Apache Sitgreaves National Forest, Arizona.

Emerges from low gradient wetlands; often indistinct or multiple sources seeping from shallow, unconfined aquifers.

For Example: Soap Holes, Elk Island National Park, Alberta, Canada


Sketch of Helocrene spring type. A=aquifer; I=impermeable stratum; S=spring source. The inverted triangle represents the water table or piezometric surface. Fault lines are shown where appropriate.

Helocrene springs emerge diffusely in a marshy, wet meadow setting rather than having a discrete source. Hynes (1970) distinguished helocrenes from limnocrene types described by Bornhauser (1913). Alberta's well-known soap holes (mud springs) provide examples of helocrenes. Similar to quicksand, these features are "a part of the land surface characterized by a local weakness of limited extent underlain by a mixture of sand, silt, clay, and water"  (Toth 1966). Groundwater discharge from these helocrenes is typically saline. Other helocrenes may have fresh water, but low oxygen concentrations, yet still support many wetland species. Hot water emerges from some helocrenes where they support primarily bacteria, while hypersaline helocrenes can support marine relict taxa (Grasby and Londry 2007).