Overview

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1998-12 Excerpt: ...the Cooper Mountain-Bull Mountain area was declared a critical ground-water area by the Oregon State Engineer in 1974, and restrictions were placed on both pumping and the construction of new wells. Additionally, in 1974, when the Wolf Creek Irrigation Project began supplying water for irrigation from the Tualatin River, the use of ground water for irrigation further decreased. As a result, water levels in the basalt aquifer in that area began to rise. However, hydrographs from the remaining wells shown on figure 18d indicate a progressive, long-term water-level decline. FIGURE 18a.--Water levels in wells completed in the hydrogeologic units in the Portland Basin and in the Tualatin Basin. Graph number (1-16) is also well number on figure 17. FIGURE 18b.--Water levels in wells completed in the Willamette aquifer, central Willamette Valley. Graph number (1-16) is also well number on figure 17. FIGURE 18c.--Water levels in wells completed in the Willamette aquifer, southern Willamette Valley. Graph number (1-16) is also well number on figure 17. FLOW WITHIN AQUIFERS During the winter and spring, when the regional water table is highest, some wells completed in the Willamette aquifer begin to flow (water levels rise above land surface); these wells usually cease to flow during the summer. In order to eliminate this variation in ground-water flow patterns caused by precipitation variability, water-level measurements collected during the summer and fall, when the water table is lowest, were used to map the water table (pl. 1). The water table mapped in plate 1 coincides with the potentiometric surface of the Willamette aquifer, except in the Tualatin Basin, where it coincides with the potentiometric surface of the Willamette confining unit, and in certain are...

Full Product Details

9781232160588

Table of Contents

Reviews

Author Information

Tab Content 6

Customer Reviews

Recent Reviews

Countries Available