Hydraulic Connection between the Blackfoot River and the ESPA

Hydrogeology

No pervasive impermeable layer to prevent hydraulic communication.

Elevation Profile Snake River conceptualized to have a 30-foot thickness of saturated material below the river (hydraulic river bottom). Snake River conceptualized to have a 30-foot thickness of saturated material below the river (hydraulic river bottom). If Blackfoot River bed is sufficiently close to the water table, it may be reasonable to assume hydraulic connection. If Blackfoot River bed is sufficiently close to the water table, it may be reasonable to assume hydraulic connection. A 30-foot hydraulic river bottom may not be applicable. A 30-foot hydraulic river bottom may not be applicable.

Elevation Profile

Ground Water Elevation and River Flow No obvious ground water flow pattern to indicate connection. No obvious ground water flow pattern to indicate connection. Based on a limited number of wells. Based on a limited number of wells.

Only one stream gage on the Blackfoot River. Only one stream gage on the Blackfoot River. Unable to assess gains/losses on this reach of the Blackfoot River. Unable to assess gains/losses on this reach of the Blackfoot River.

Ground Water Elevation and River Flow Correlation Coefficient = 0.58 Correlation Coefficient = 0.58 Coefficient of Determination = Coefficient of Determination = Similar water use patterns and shared regional climate. Similar water use patterns and shared regional climate. Frequent No-Flow or Very Low-Flow. Frequent No-Flow or Very Low-Flow. Effectively reduces hydraulic river bottom. Effectively reduces hydraulic river bottom.

Conclusions The separation distance between the Blackfoot River and the aquifer progressively decreases in the downstream direction. The separation distance between the Blackfoot River and the aquifer progressively decreases in the downstream direction. The river is more likely to be hydraulically connected to the aquifer near the confluence with the Snake River. The river is more likely to be hydraulically connected to the aquifer near the confluence with the Snake River. Ground water flow direction appears to be irrespective of the Blackfoot River. Ground water flow direction appears to be irrespective of the Blackfoot River. A correlation coefficient of 0.58 and a coefficient of determination of 0.33 suggest that visual similarities do not reflect a strong correlation or dependent relationship. A correlation coefficient of 0.58 and a coefficient of determination of 0.33 suggest that visual similarities do not reflect a strong correlation or dependent relationship. The similarities are probably an indication that water levels and river flow are both influenced by irrigation practices and climate. The similarities are probably an indication that water levels and river flow are both influenced by irrigation practices and climate. Flow measurements indicate that flow in the Blackfoot River frequently drops to zero. Flow measurements indicate that flow in the Blackfoot River frequently drops to zero. Any hydraulic connection between the river and the aquifer may be transient. Any hydraulic connection between the river and the aquifer may be transient. The river and the aquifer probably exhibit some degree of hydraulic exchange, but the flow in the river would not be head- dependent. The river and the aquifer probably exhibit some degree of hydraulic exchange, but the flow in the river would not be head- dependent.