What can be said about the Niobrara formation?

The Niobrara formation is well-known for its geological characteristics, particularly its composition, which includes shaly chalk and limestone. This formation has gained attention not only for its hydrocarbon potential but also for its role as a secondary aquifer. As a secondary aquifer, it provides some water resources, although it may not be the primary source in the region compared to more prolific aquifers. This composition allows it to retain some water, offering accessibility for use in irrigation and other purposes.

Considering other options, while sandstone is a common mineral in many aquifers, it does not define the Niobrara formation. Additionally, classifying it as a confined aquifer with poor water quality does not accurately reflect its characteristics and usability. Lastly, the claim about having no significant water use underestimates the formation's importance, particularly in the context of its secondary aquifer status, thus reinforcing the viability of option C as the most accurate statement about the Niobrara formation.