WEBER COUNTY — Ogden Valley’s groundwater is plentiful and of high quality, but it needs to be managed carefully as the valley faces continued growth, according to a new report.
The Utah Geological Survey (UGS) released a detailed study of the valley’s groundwater system in mid-November.
The study focuses on the valley that’s home to Eden, Huntsville and Pineview Reservoir, which Northern Utah locals sometimes refer to as the Upper Ogden Valley.
The valley is currently home to 7,000 residents, but that population could grow to as many as 28,000 residents by 2060 under current zoning, the report said.
J. Lucy Jordan, senior hydrogeologist with the UGS and lead author of the report, thought the report’s most interesting finding was “how much the surface water and groundwater are interconnected — how much movement there is between the streams and the groundwater.”
This is a little unusual in Utah, Jordan said, and it happens because Ogden Valley’s water table is higher than water tables in many other valleys in the state. The valley also has more streams than usual.
This interconnection between surface water and groundwater is both a benefit and a vulnerability, Jordan said.
The benefit is that this connection maintains a higher volume of groundwater.
In many other valleys, water levels in wells have been declining over time, Jordan said, but that’s not the case in Ogden Valley, in part because of the interconnection between groundwater and surface water.
This close connection means that the water in the streams can replenish the groundwater system, Jordan said.
But this same connection means that the groundwater is more easily contaminated by the water from the surface.
While the groundwater quality remains high in Ogden Valley, the report found an increase in nitrates in the groundwater, which means that some contaminates from septic tank leachate are making their way into the groundwater system, even to groundwater that is deeper in the earth.
“I think the most important thing for the general resident and water user (in Ogden Valley to understand) is how vulnerable that system is to surface water influence, so if there’s anything in your streams, if there’s anything you’re putting on your land, it gets into that aquifer system ... pretty quickly.”
Conventional septic tank systems dispose of sewage by releasing it into the soil, generally not very deep in the ground. This waste water, called leachate, percolates down into the groundwater system.
Jordan estimates that more than half of residents in Ogden Valley use conventional septic tanks to dispose of sewage.
The report recommends that communities in the valley change their current waste water treatment practices, Jordan said.
“Water resource managers should be vigilant in protecting the quality of Ogden Valley’s groundwater resources as population and use grows,” the report concluded.
Two options to reduce leachate are for community members use more sophisticated septic tanks that treat waste water before it’s released into the soil or to move to centralized waster water treatment practices, like a sewer or lagoon system.
While actions like this will protect the quality of the groundwater, different steps are required to prevent its depletion.
The Utah Division of Water Rights will reference this report when making decisions about water rights applications, Jordan said. The report also contains water budget numbers that are the most important feature of the report for planners, including Weber Basin Water Conservancy District and Ogden City.
“This (report) is ... another tool that water managers can use to understand the groundwater system up there,” Jordan said, “and provides the basis for policy makers to make those decisions.”