ES476-576 Hydrology In-Class Exercise: Introduction to Hydrogeology of the Monmouth-Independence Area Attached is a portion of the 7.5-minute Monmouth Quadrangle, showing the Monmouth-Independence “metropolitan” area. The hand-marked points are well locations showing water level elevations from 1972. The second figure is a cross-section showing the generalized geology of the Willamette Valley from Corvallis, westward to Lebanon. While this cross-section is south of Monmouth, the general geologic relations are also present in the Monmouth-Independence area. For purposes of comparison, the Monmouth-Independence area is located approximately in the same valley position as the point labeled “Corvallis DH13-88 well”. The Willamette river is located on the profile immediately adjacent to the well (about 2 mm to the east, in profile units). Based on examination of the generalized geology at the west edge of the profile and using the Monmouth-Independence groundwater map. Conduct the following tasks / answer the following questions. 1. What types of Earth materials occupy the subsurface environment in the Monmouth-Ind. Area? Bedrock? Alluvium? Or ? 2. What type of aquifer conditions do you predict in the Monmouth area? Confined or unconfined? 3. Are the water level elevations in the wells on the base map likely depicting a water table or potentiometric surface under artesian conditions? 4. What is the local “basement” bedrock that underlies the valley material in the Monmouth area? 5. On the basemap with groundwater elevations, use a 5 ft contour interval and draw a groundwater contour map. 6. Which direction is regional groundwater flow in the Monmouth area? 7. How does the elevation of the Willamette River compare with groundwater levels in the area? 8. Do you think the Willamette River is gaining or losing in this reach? 9. Locate the two wells labeled with values of “132” and “136” on the west side of the river, across from Independence. Do you think groundwater flow on this portion of the map parallels that of the west side of the river? 10. Discuss the relationship between hydraulic gradients in the groundwater system, and the presence/position of the Willamette River in the Monmouth-Independence