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SECTION 2 Study Area Characteristics Table 2 -8 Hydric Soils in River Road Santa Clara Basin Location Hydric Soils (percent) Within UGB 11% Outside UGB 37% Total Basin 22% Source: USDA Soil Survey of Lane County Area, Oregon, 1987. 2.9 Groundwater Two aspects related to groundwater need to be given special consideration when planning for stormwater management. The first relates to the regional aquifer that underlies much of the lower Willamette Valley basin. This aquifer is the source of drinking water for rural residents and several nearby communities (i.e., Springfield, Coburg, Junction City) and has also been investigated as a potential future source of water for Eugene. For this reason, consideration needs to be given to the effects that stormwater management can have on groundwater quality and quantity. The second issue relates to depth to the water table. Map 11 shows the depth to high water table during the wet season. This information is linked to soil type and comes from the USDA Soil Survey of Lane County. During the course of the year, these elevations respond to rainfall amounts and, therefore, vary accordingly. As with hydric soil location, the Northwest Expressway is a definitive boundary where deeper water table elevations are found to the east and shallower depths to the west. As part of this study a more detailed analysis of high groundwater was conducted by reviewing well logs from the Oregon Water Resources department. The results of the evaluation showed that seasonal high groundwater levels are approximately 8 feet deep on average in this basin. A copy of study results is provided in Appendix E. With regard to the issues of aquifer protection and depth to the water table, the numerous drywells used for stormwater management in this basin present a unique environmental problem because drywells have the potential to discharge surface water pollutants directly to groundwater without sufficient treatment. Congress enacted groundwater protection rules in 1974 under the federal Safe Drinking Water Act (SDWA). The U.S. Environmental Protection Agency (EPA) administers these rules under Title 40 of the Code of Federal Regulations (CFR) Parts 144 -148. In Oregon, the EPA has delegated the regulation of groundwater protection rules to the Department of Environmental Quality (DEQ). The DEQ regulates this program for the EPA under the Oregon Administrative Rules (OAR) Chapter 340, Division 44. As part of these groundwater protection rules, DEQ specifies a minimum of 10 feet of separation between the bottom of a drywell and the seasonal high groundwater. Due to high groundwater in a large portion of the River Road Santa Clara basin, most of the UICs in this area do not meet the necessary separation criteria and cannot, therefore, be Authorized by Rule by the DEQ. Both the City of Eugene and Lane County have registered their known UICs with the DEQ and have applied for a Water Pollution Control Facility (WPCF) permit to manage the UICs until they can 0:\25695978 Eugene RR -SC Final Basin P1an\Master P1anTINAL 2- 2010\Master_Plan 3- 11- 10_FINAL_ Word _Version.doc 11 -28