Technical reports (also called scientific reports) are most often produced by agencies responsible for scientific investigations of natural phenomena, problems or processes. These agencies are commonly governmental (local, state, federal, international) or educational agencies and organizations. Technical reports differ from articles in scientific journals in that technical reports usually do not undergo the intensive peer review process that journal articles are subject to. The review process for technical reports is a more limited process involving review within the organization that is responsible for producing the report.
Some examples of agencies that produce technical reports are listed below.
In library catalogs, technical reports are treated most often like books, so you should be able to identify them with normal book searching methods. Sometimes, however, technical reports are treated like a series of publications, and there may not be individual titles listed for each report. This method is common for many of the U.S. Geological Survey technical reports. If this is the case (as with the U.S. Geological Survey reports in the SMC Library) then you need to actually browse the shelves in the library.
Search for special publications through the web sites of these agencies:
USGS Central Midwest Water Science Center (This site has lots of links to data.)
In many cases, the full text of the reports are available for download free of charge.
Other U.S. states, and some other countries too, have agencies with similar names. Search Google using the name of the state and words like "water resources" or "water survey" to find other state agencies.