Characteristics of Good Watersheds

Riparian areas, areas along the stream banks, are covered by transitional vegetation and act as buffers between a waterway and the surrounding area of differing land use. These grasses, forbs, and trees reduce bank erosion by anchoring the soil and also decrease the amount of sediment from runoff entering the system by absorbing and allowing infiltration of the water to the soil. These buffer areas also provide critical biologically diverse habitat that functions as a wildlife corridor enabling many species to better co-exist with the more intense land use practices in the surrounding region.

Shade is a necessary component of a healthy watershed because it provides a protective structure over the water, thereby decreasing the amount of sunlight able to penetrate. This decrease in sunlight results in less extreme temperature gradients of the surface and sub-surface water. Water that is cooler can hold more oxygen for aquatic species to use.  Shade provided by trees and other vegetation also supplies annual organic matter (dead leaves or plants) to the system's nutrient pool. These additional nutrients are easily incorporated into the system.

The quality of water is another critical component of a healthy watershed. Good watersheds usually function best with low turbidity, minimal suspended sediment in the water, and infrequent shifts in water levels.
 
• Turbidity, the cloudiness of water due to excess sediment, is an extremely important factor in maintaining aquatic
diversity. Many sensitive organisms, especially fish, require relatively clear water conditions for reproducing and finding prey. Some organisms, like shell-fish are filter-feeders and continually filter the water in the environment.  These organisms can become choked by sediment and eventually die in heavily turbid waters.
• Frequency and intensity of fluctuating water levels are also very important considerations. Stable rivers can
accommodate natural levels of water resulting from typical storms. However, with increased runoff water entering the system from surrounding areas with impervious roadways and surfaces lacking vegetation, water levels quickly rise to less manageable levels. High water levels, with greater than normal velocities can accelerate the rate of bank erosion, increase sediment load, and displace aquatic species of plants and animals.

The fourth component necessary for a properly functioning river system is the formation of meanders. Meanders in a river are turns in the banks that result in a winding course for the waterway. These meanders slow the water down and allow for deposition of sediment and other suspended material on their banks. As healthy rivers and streams age, they will naturally form more meanders. Often, however, due to development in a particular region of a watershed, water pathways are channelized and purposely straightened. Accommodating for these structures in a stream or river's system should be advised.

By combining all of the characteristics above (riparian areas, shade, good water quality, and meandering) a good functioning watershed will become hospitable to multiple species, both plant and animal. Biodiversity is extremely valuable to both the natural order of the system and human recreation and non-consumptive uses. Greater biodiversity, greater numbers of species able to occupy a certain area, is also aesthetically pleasing to human observers. Such areas should be preserved and managed to create habitat suitable for the greatest amount of natural productivity. The physical diversity of environments in streams should also be considered.  Different types of internal habitat and structure such as pool and riffle sequences and vegetation also help to diversify the system and provide for increased stability.