South Platte River Basin: DWR Sterling Groundwater Monitoring Effort

Click here for the Sterling Groundwater Monitoring Effort website from the Colorado Division of Water Resources. They write:

Homeowners have relayed their concerns about high groundwater levels in the Country Club Hills and Pawnee Ridge subdivisions in Sterling to state officials. The DWR and CWCB are conducting an independent analysis at each subdivision. The agencies have undertaken an effort to monitor groundwater levels and characterize the hydrogeology within the areas of interest. The objective of this groundwater monitoring is to identify relationships between the hydrology of the area and the high groundwater levels. Preliminary information and data obtained from this investigation is updated monthly.

Here’s a report from David Martinez writing for the Sterling Journal-Advocate. Here’s an excerpt:

Ralf Topper, senior hydrogeologist at the DWR, said at a community meeting that results so far show that a mix of geologic deposits and structure – in terms of bedrock – have an effect on the level of water tables.

Several area farmers and residents have complained of low water tables, or levels below ground that are completely saturated with water. Spots with water tables as high as at four of five feet below the surface can damage crops and cause basement flooding.

So the DWR and the Colorado Water Conservation Board started conducting an independent analysis of the city’s subdivisions.

The agencies are monitoring groundwater levels and characterizing the hydrogeology around the city. The goal, according to the DWR, is to find relationships between the area’s hydrology and the high groundwater levels.

“We’re looking at all of the inputs and outputs,” Topper explained. “Why are groundwater levels changing? What’s the mechanism for changing?”

He added that they’ll collect data on stream flows, diversions, recharge ponds, climate and large capacity oil pumping. All of that will then go to third party consultants to analyze.

The DWR has studied 16 piezometers – devices that measure groundwater pressure – between the Sterling subdivisions of Country Club Hills southeast of Northeastern 18 Golf Course and Pawnee Ridge north of County Road 30 and east of Ballpark Road since May.

From the measurements, the DWR found that the geology from spot to spot varied between thick and thin layers of gravel, sand, clay and shale (bedrock).

The clay is important, Topper said, because water levels where clay exists tend to be shallower.

“(The results) gave us an indication that we’re really looking at a system that is highly variable in terms of the subsurface,” he said. “The assumption was (the land’s) homogenous…. Everyone says it’s sand and gravel. What we’re finding in this area, it’s not the case.”

And the water tables can vary in any given spot, as well.

“Nested” piezometers, which measure at different levels from the same bore hole, showed that water tables existed in as many as three layers in Country Club Hills. Some tables were as shallow as three feet, while others were as deep as 24.

More South Platte River Basin coverage here.