The Groundwater Hydrology Report resulted from data collected and analyzed at key locations throughout the Pebble project area. Since 2004, a number of Alaska-based consultants have studied water quantity, flow rates and flow directions of the groundwater system in the Pebble project area. The study also includes an evaluation of the interaction between groundwater and surface water.

To study the groundwater, the scientists used 259 piezometers, which are used to measure the hydraulic head of groundwater in aquifers, and monitoring wells at 196 sites in the North and South Fork Koktuli River and the Upper Talarik Creek watersheds.

Elements of the Pebble Project groundwater hydrology study include:

• Characterization of the subsurface geology to identify fine-grained materials (silts and clays) versus coarse-grained materials (such as sands and gravels);

• 94 rising and falling head tests to measure hydraulic conductivity or the rate at which soil or rock allows water to flow;

• Seven pumping tests where one well is pumped and several near-by wells are monitored for changes in water level;

• Hourly and monthly groundwater elevation monitoring;

• A seep inventory of groundwater discharges to surface (including location and size classification) and flow rate monitoring at selected seeps throughout the study area.

Additional hydrology studies are planned for 2008 and data from those tests are scheduled to be released next year.

Pebble Partnership CEO John Shively said the partnership will release its collected data to the public with little or no prior analysis over a period of months, rather than all at once, because of the tremendous volume of information and strict requirements for quality assurance and control. A comprehensive environmental baseline document will subsequently be prepared and appended to the project permit, he added.