3.16 Surface Water Hydrology
PEBBLE PROJECT CHAPTER 3: AFFECTED ENVIRONMENT FINAL ENVIRONMENTAL IMPACT STATEMENT 3.16 SURFACE WATER HYDROLOGY This section describes the affected environment for existing surface water conditions in the Environmental Impact Statement (EIS) analysis area, including the mine site, transportation corridor, port, and pipeline corridor for all alternatives and associated variants. The EIS analysis area includes watersheds (i.e., drainage basins), numerous streams, lakes (including Iliamna Lake), marine water (Cook Inlet), and wetlands (see Section 3.22, Wetlands and Other Waters/ Special Aquatic Sites) that have the potential to be impacted by the project. The discussion below addresses potentially affected waterbodies, baseline water balance model, floodplain magnitude and frequency, flood hazards, floodplain functions and values, tides, and water use (both surface and groundwater). Drainage basins (synonymous in this document with catchments, watersheds, sub-catchments), flow patterns, discharge/recharge, and interaction with groundwater are described. Section 3.17, Groundwater Hydrology, provides more information regarding groundwater conditions. Section 3.18, Water and Sediment Quality, addresses quality of surface water, groundwater, and sediment/substrate in waters and wetlands. Baseline surface water conditions have been characterized by studies conducted from 2004 through 2012 (Knight Piésold et al. 2011a, 2015b), which also considered previous studies and data collected by the US Geological Survey (USGS) and US Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS). Knight Piésold et al. 2011a provides an overview of regional hydrology in the Bristol Bay drainages, and hydrologic context for the mine study area1 and transportation and pipeline corridors. The baseline studies are summarized in this section. Details regarding meteorological inputs to the baseline watershed model (BWM), including model calibration and validation, are provided in Appendix K3.16.
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