Water quality

Water quality is a critical issue across the United States and globally. Over the past fifty years, the amount of nutrient input into natural water systems has been dramatically reduced from nonpoint sources such as agricultural fields. Best management practices such as reduced tillage, vegetative filter strips, and nutrient management have reduced edge of field sediment loss, nitrogen loss (surface runoff and subsurface flow), nitrogen loss, and phosphorus losses. Today’s farmers are producing more corn and soybeans with fewer resources by planting genetically modified crops with drought-resistant traits and maximizing infiltration rates for their soil type. With the help of programs through the USDA that seek to protect water at the source and nutrient practices such as the 5 Rs (right source, right rate, right time, right place and right irrigation), the production of corn and soybeans and their impact on water quality have greatly improved.

Livestock farmers are also part of improving the quality of water by investing in practices such as: prescribed or planned grazing that increases ground cover in pastures through rotational use reduces erosion and increase water infiltration; waste storage and management help to reduce runoff to keep excess nutrients from entering watersheds. The quality of water on farm is of critical importance to protect livestock from potential disease organisms and give animals a source of healthy drinking water.

Chemical tests are designed to give accurate readings of the current water chemical properties such as dissolved oxygen, nitrates, nitrites, phosphate, and ammonia levels. Many of these chemical properties can change quickly within an aquatic system and have immediate effects on the organisms that live there. Dissolved oxygen, for example, is the amount of gaseous oxygen (O2) dissolved in an aqueous solution and is vital for all aquatic life. It is in constant flux due to the balance between respiration and decomposition of organisms that require dissolved oxygen and photosynthetic activity and diffusion that increase it.

Biological tests are designed to indicate the overall health of a water system based upon the vertebrate and macroinvertebrate biodiversity within the water system. Organisms are good indicators of seasonal and annual water quality due to their range of tolerance for chemical and physical factors within the aquatic system. For example, mayflies and rainbow darter fish both require water with high dissolved oxygen levels and are not found within systems with low levels of DO.

Physical factors help to gauge the stream structure, flow rate, depth, turbidity, and temperature of the water. Many riparian factors may influence physical tests such as the shade cover of trees that decrease water temperature, reduce soil and nutrient erosion, and support stream integrity by maintaining stream banks. Simple changes in riparian zones can cause a stream to go into a state of chaos and rapidly change physical, chemical, and biological indicators for the worse.