What is Limnology?
Originally the word limnology was used in reference to the study of lakes and is derived from the Greek word limnos, meaning pool, lake, or swamp. Though the field of limnology has largely developed through the study of lakes, the scope has broadened over the years to embrace any fresh or salt waters, which are contained within continental boundaries. This includes lakes, reservoirs, rivers, streams, estuaries, and often overlooked microhabitats like springs, fens, and bogs. Limnology involves the physical, chemical, and biological characteristics and processes of aquatic systems and their watersheds

Iowa's Water Resources
Iowa has several large flood control reservoirs and many small impoundments. Some natural lakes occur in northwest and north central Iowa (30 lakes over 100 acres). However, the state's network of rivers and streams represent the vast majority of our water resources. Our rivers provide drinking water, water for crops and livestock, industry, cooling, cleaning, and production of electric power, transportation/navigation routes and, unfortunately, often must carry away the wastes produced by these activities. The aesthetic and recreational value of our streams is also important for Iowa's water resources.

Evaluating Water Quality
The Limnology Section devotes most of their time sampling Iowa's surface waters (usually rivers and streams) and evaluating water quality and the impact of human activity. Iowa's water quality standards are largely based on chemical criteria- that is the concentrations of various chemical compounds cannot exceed certain levels under certain conditions in our surface waters. As a result, water sampling and chemical analyses are vital to evaluating water quality. However, chemical monitoring is really just a snapshot of the conditions at the time of sampling. For example, most of the fish kills in the state are related to very short-term events, often associated with a manure/chemical spill or precipitation event. The slug of polluted water may be present at a location on a stream for only several hours, and is likely to be missed by routine chemical monitoring. Incorporating biological monitoring into the evaluation process helps to complete the picture of a stream's condition. The fish, aquatic insects, and other invertebrates in a stream are continuously exposed to what is in the water and species display varying water quality tolerances. Some require clean, nearly pristine conditions while some tolerate, and even thrive, in somewhat poor water quality. Stream inhabitants (fish and bugs) also reflect the physical (habitat) quality of a stream. Water quality assessments typically involve one or more of the following:

• Water chemistry
• Quantifying physical/structural (habitat) aspects of a waterbody
• Characterizing biological communities present (fish, benthic macroinvertebrate, and algae & macrophyte surveys)