In terms of water quality, Lake Nipissing is classified as a mesotrophic lake, meaning it is moderately enriched with nutrients. Water quality has a direct impact on the health of a lake's fishery and on the appeal to the recreational user. Lake Nipissing is unique in that it overlies a bed of precambrian bedrock covered by extensive sand and clay deposits of glacial origin. The water quality of any lake is determined by the its geological history coupled with physical geography and inflow characteristics.

Extensive water quality research was conducted during the open water period from 1988-90 as part of a program to determine the probability of sustaining the lakeÕs fish population. Results from the study indicate that the majority of the lake has nutrient concentrations suitable for a healthy warmwater fishery. This is no surprise as Nipissing has always been a very productive lake as many an angler will contend.

Lake Nipissing Inflow
The watershed of Lake Nipissing is made up of a drainage of twelve streams and rivers that flow into the Lake. Inflows that drain areas of agricultural activity may have a profound impact on water quality due to soil erosion and the use of raw manure and chemical fertilizers.

Calcium content
Calcium levels in Lake Nipissing were of particular interest in recent water quality studies as calcium is an indicator of a Lakes ability to neutralize acid rain. Research shows that Lake Nipissing is well buffered against acidification despite being located relatively close to Sudbury, a major source of sulphur deposition. Calcium levels also tell whether a lake is susceptible to invasion by the zebra mussel (Dreissena polymorpha) that has recently colonized the Great Lakes. Fortunately, calcium levels in Nipissing have been determined to be too low to satisfy the growth requirements by the larvae of this nuisance mollusc.

Dissolved oxygen
Like most animals, fish must breathe and Lake Nipissing just happens to be the ideal place for such an activity. The long wind-swept area and shallowness of the lake aid in the thorough mixing of the water. This churns air into the water ensuring that the lake is well oxygenated. The surveys indicate that with the exception of a deep water area near the mouth of the French River, the dissolved oxygen content of Lake Nipissing is suitable for oxygen loving aquatic organisms throughout the year.

Nutrient levels
In general the nutrient levels of a lake ecosystem can be defined as those chemical constituents in the water that determine the growth and productivity in the body of water. Phosphorous and chlorophyll measures are normally used as indicators of a lakes ability to support higher forms of life such as small shrimp-like organisms (crustaceans) and fish.

In the 1960's and early 70's, the term phosphorous emerged as a household name. Phosphorous is the nutrient which is largely responsible for plant growth in aquatic ecosystems. The increased use of this chemical in laundry detergents was to blame for the increase in aquatic plant and algae growth. Lost was the aesthetic appeal of many lakes as once clear waters became murky and increased plant growth clogged boat propellers.

Phosphorous and chlorophyll, the pigment responsible for the green colour of plants, are the two parameters used to determine the trophic status of a lake. Based on recent studies, Lake Nipissing is said to be mesotrophic meaning the lake is moderately rich in nutrients. Concentrations of phosphorous and chlorophyll vary throughout the year and throughout the lake. In general Callander Bay and the north west end of the lake have the highest levels of these nutrients.

Chlorophyll is an indirect measure of the amount of algae in a lake which is often the first link in a food chain. As these nutrients trickle through the organisms of the food web, they influence the lakes productivity at all levels. The productive fishery of the south shore area can be explained by high concentrations of chlorophyll and phosphorous.