Surface water and groundwater interaction in the Fortune Creek watershed: implications for fish protection and water management (Year 2)

Fortune Creek is a regulated system near Armstrong and the Spallumcheen Valley. The Creek provides habitat for resident rainbow trout, juvenile coho and Chinook salmon. While DFO and the City of Armstrong have worked cooperatively to try and maintain stream flows to sustain fish, water management in the watershed has become increasingly difficult.

A scoping study indicated that the upper creek experienced loss of surface water to groundwater, and also recovery from groundwater. A multi-year research program to fully understand surface-water ground interactions was proposed. Surface water and groundwater interaction is a critical factor for determining water quantity, quality and water thermal regime for fish habitat. In year one, geochemical methods to identify groundwater discharges were found to be confounded by anthropogenic influences on creek water chemistry. Year two proposed to use thermal methods to reveal details of surface water groundwater interactions. Preliminary thermal studies identified that specific stream reaches where groundwater discharged were large in scale, and hence not suited to a discharge/no discharge comparison study.

A revised proposal was submitted in May 2008 which outlined a detailed program of fish enumeration in the creek and comparison to measures of habitat suitability for the whole creek including thermal regime. The program included weekly counts of all fish species from July to October 2008, DNA analysis of the fish populations and detailed continuously datalogged thermal measurements. Thermal conditions were found to be unsuitable for the majority of the creek during summer. Data analysis in winter 2008/2009 is developing specific statistical relationships between thermal conditions and fish presence and quantity. Further analysis is developing heat budgets for the creek to assess the effects of shade and increased flow on temperature regime (ie: two possible remedial efforts), and to quantitatively assess the influence of groundwater on the thermal budget.