PROJC00757 - Laserfiche WebLink

Home Browse Search

, ' . . f D. Objective The objective of this study is to define the present quantity and quality of the ground-water resources of the mountainous part of Jefferson County, monitor the ground-water levels, precipitation, and water quality, and provide a method to simulate effects of current and future development on the resource. E. Approach The mountainous parts of Jefferson County covers an area of about 550 square miles (about 385 square miles susceptible to additional development), presenting a formidable task for a detailed assessment of ground-water resources. In order to meet the objectives of the study in a timely and , cost effective manner, a phased approach is proposed. The major phases of the study include (1) defining the ground-water resources, (2) developing an effective method to monitor the resource, and (3) developing a means to simulate future effects to the resource using a digital model. The water-resources investigation began with a pilot study in the Turkey Creek Basin. The pilot study is using a phased approach has been undertaken in the area of the U.S. Highway 285 corridor in the Turkey Creek drainage. The pilot study provides an area to refine and modify methods to be incorporated into larger area study. The pilot study efforts for 1998 have included: collecting existing data about the Turkey Creek Basin, including well and discharge records from the State Engineer's Office and the USGS database and precipitation records from the National Weather Service; installing the surface-water gage on Turkey Creek; installing rain gages throughout the basin; identifying homeowner wells for water- quality sampling; identifying wells for water-level measurement; and developing the initial model of the basin water budget. Continuing efforts for the remainder of 1998 and beginning of 1999 will include the water-quality sampling, water-level measurement, surface-water discharge measurement, precipitation data collection, installation of the evapotranspiration tower, refinement of the water budget, and investigation of the fracture zones. E.1. Definition of ground water resources Ground water resources can be defined by: determining the volume of ground water in storage; the rate of replenishment of the ground water by precipitation and irrigation infiltration; the rate of loss of ground water to wells, streams, vegetation, and ground-water outflow; ana the rate of return flow through streams and septic systems. These quantities together constitute a water budget. Similar to a financial budget, a water budget accounts for all sources of inflow (income) and outflow (expenditures), with the total equaling the change in ground-water storage (change in the bank account balance). In a balanced system the average inflow (income) would match the average outflow (expenditures) with minimal impact on the average storage (principal). Like a long-term investment, problems arise when the there are continuous withdrawals from the storage (principal). The information required to develop the definition of the ground-water resource comes from many sources. Ground-water levels can be developed from the State Engineer's Office's well records and current water level measurements can supplement these data. Ground-water storage information can be determined from saturated thickness, porosity, hydraulic conductivity, and hydraulic gradient obtained from the State Engineer's Office, local drillers, and on-site measurements (including aquifer tests, borehole geophysics, and fracture mapping). Average precipitation for the area can be obtained from the National Weather Service, the State Climatologist, and real-time precipitation gages. General irrigation data can be obtained from the State Engineer records and individual interviews. Infiltration rates can be determined using existing soil data from the Natural 2