Abstract

Ogden Valley is in eastern Weber County, north-central Utah, about 10 miles (16 km) east of the city of Ogden. It is 12 miles (19 km) long and 3 miles (5 km) wide, encompassing an area of 37 square miles (96 km²). The principal drainage in Ogden Valley is the Ogden River and its tributaries. The South, Middle, and North Forks of the Ogden River enter the valley from the east, northeast, and north, respectively. These forks, other smaller streams flowing from the surrounding uplands, and valley-floor springs discharge into Pineview Reservoir. Water released from the reservoir flows west through the Wasatch Range via Ogden Canyon, the only surficial outlet for water in Ogden Valley.

Ground water in Ogden Valley occurs under perched, confined, and unconfined conditions in the valley fill to depths of 750 feet (230 m) and more. In the western portion of Ogden Valley, lacustrine silts, which occupy an area of about 10 square miles (26 km²), form a confining layer in the upper part of the valley-fill aquifer system. Although several low-permeability silt and clay lenses occur in the valley fill beneath this layer of fine-grained lacustrine deposits, they are not areally extensive and the entire system below the confining layer behaves hydraulically like a single aquifer. Beyond the outer edge of the confining layer, ground water is under unconfined conditions. Ground water also is under unconfined conditions in sediments above the silt confining layer.

Ground-water quality in the Ogden Valley valley-fill aquifer system is excellent. Ground-water chemistry in the valley-fill aquifer system is dominantly calcium bicarbonate with total-dissolved-solids (TDS) concentrations generally less than 350 mg/L. Average background TDS in the Ogden Valley valley-fill aquifer system is 200 mg/L. Nitrate concentrations range from less than 0.1 to 11 mg/L. The one well having water with a nitrate concentration of 11 mg/L is located near the mouth of Middle Fork canyon. The next highest nitrate concentration is 6.5 mg/L.

In Ogden Valley there are approximately 2,300 individual on-site wastewater disposal systems. The majority of these systems are “conventional” septic tank soil-absorption systems. There are also 22 low-pressure pipe systems, six at-grade systems, and one mound system. Based on a recent approval for the Weber-Morgan District Health Department to use alternate systems, the potential for unlimited use of new at-grade and mound systems exists. New low-pressure pipe systems are not allowed.

As a result of an evaluation of water quality and waste-disposal methods in Ogden Valley, a committee formed by the Weber-Morgan District Health Department, the Pineview Basin Water-Quality Committee, submitted recommendations for future wastewater management practices in Ogden Valley to the Weber County Commission. Recommendations included a prioritized list of wastewater disposal methods to be used, a phased plan for establishing a valley-wide wastewater management district, and a maximum overall density of septic-tank systems.