Fond du Lac Lakes and Streams Data

The Fond du Lac Office of Water protection conducts its monitoring program through site-specific designs and sampling locations that we believe are most appropriate for each waterbody. Our monitoring program is tailored to specific waterbody types and their designated uses, which include fisheries lakes, wild rice lakes, five primary streams, and a large river. We use fixed stations for our ongoing lake and stream monitoring program.

Water Quality Parameters

Protecting human health requires monitoring for indicators that assess the safety of eating fish or other aquatic wildlife, or of swimming and boating. Protecting ecosystems requires monitoring for indicators of diverse, healthy aquatic plant and animal communities; indicators are also needed to assure that water quality and sediment conditions are capable of maintaining those biological communities. The parameters chosen for our monitoring program are commonly used by state and federal agencies and other monitoring groups, and our methods for collection and analysis are standard.

Physical Parameters: Field measurements of physical parameters are performed using a Hydrolab Minisonde and Surveyor datalogger.

Total Suspended Solids: a measurement similar to turbidity that indicates how much particulate matter is in the water. Total Suspended Solids (TSS) are solids in water that can be trapped by a filter. TSS can include a wide variety of material, such as silt, decaying plant and animal matter, industrial wastes, and sewage. High concentrations of suspended solids can cause many problems for stream health and aquatic life.

Temperature: a measure of how cool or warm the water is. Lake and stream temperatures change with the seasons and with depth. Cool water temperatures are critical for maintaining healthy trout populations in Otter Creek.

Dissolved Oxygen (DO): a measure of the amount of oxygen dissolved in the water and available to aquatic organisms. Slow moving water has a lower DO concentration than turbulent water because it does not mix as frequently with the atmosphere. Low DO concentrations can also be attributed to warm water temperature and increased nutrient inputs, because algae blooms can form and draw down the oxygen supply. When less dissolved oxygen is available for aquatic organisms, it leads to stress, increased susceptibility to disease, and population decline.

Specific Conductivity: a measure of the resistance of the water to electrical flow. When high concentrations of ions are dissolved in the water, the resistance of the water to electrical flow is reduced.

pH: pH is a measure of the acidity of the water. A lower pH indicates more acidic water. Most lakes have a neutral pH, though bog lakes tend to have a low pH due to dissolved tannic acids in the water.

Turbidity: Turbidity is defined as the clarity of the water. Murky water caused by too much sediment prevents aquatic plants from getting enough sunlight; sediment clogs fish gills; and pollutants often adhere to sediment particles. The EPA lists suspended sediment as the number one impairment to water quality in streams and rivers.

Secchi Disk Transparency: a measure of water clarity. A weighted white disk that is 20 cm in diameter is lowered into the water on the shaded side of a boat until the disk disappears from view. An average is taken from the measured depth where the disk disappears from view and the depth where it reappears into view. Clear water will have a larger Secchi depth measurement than murky water. Secchi measurements are part of the calculated Trophic State Index for a lake.

Chemical Parameters: We test for a suite of chemical components in lake and stream water to make sure they are within acceptable parameters.

Alkalinity: a measure of the dissolved compounds in water that shift the pH to the alkaline side of neutrality. High alkalinity usually indicates the presence of exposed bedrock in a lake.

Hardness: a measure of the concentration of dissolved ions in the water, including calcium and magnesium salts. If alkalinity is high in a lake, hardness is also usually high.

Apparent Color: a measure of the amount of light absorbed by suspended particles in the water. Lakes that contain a high concentration of organic particles such as algae will appear murky and can indicate problematic algae blooms.

True Color: a measure of the amount of light absorbed by dissolved organic carbon after particles in the water have been filtered out. Some of our bog lakes are naturally tea-colored because of dissolved tannic acids in the water.

Chloride: a measure of the concentration of chloride ion concentrations in the water. High chloride salt concentrations indicate a water quality problem, often because of a direct pollution source.

Ammonia, Nitrite + Nitrate, TKN, Orthophosphorus, and Total Phosphorus: a measure of the amount of nutrients present in the water. Nutrients are needed to drive the food chain whereby algae use these nutrients and energy from the sun to grow. The algae are consumed by zooplankton that are in turn eaten by fish. When too many nutrients get in the water from sources like fertilized lawns and farm fields, and animal and human waste, problematic algae blooms can occur. Algae blooms cause water quality problems, such as when algae use up enough oxygen in a lake that it causes fish kills.

Sulfate: if sulfate concentrations in a lake are too high, it can inhibit wild rice growth. We monitor sulfate to make sure it stays within acceptable levels for wild rice growth.

Trophic State Index (TSI): a mathematical way of determining the condition of a lake. The concept of trophic status is based on the fact that changes in nutrient levels (measured by total phosphorus) causes changes in algal biomass (measured by chlorophyll a) which in turn causes changes in lake clarity (measured by Secchi disk transparency). A lake with a low TSI value is considered oligotrophic, a lake with a high TSI value is considered eutrophic, and lakes in the zone between eutrophic and oligotrophic are considered mesotrophic.

Biological Parameters: Biological indicators include algae in lakes (chlorophyll a), periphyton in streams (chlorophyll a), zooplankton in lakes, and benthic macroinvertebrates. Only chlorophyll a and fish data are included in the table.

Chlorophyll a: a measure of a component of chlorophyll that is present in algae cells. When a lake has a high chlorophyll a concentration, it could possibly indicate a problem algae bloom due to excessive nutrients in the water. Chlorophyll a is used in conjunction with total phosphorus and Secchi depth to calculate the Trophic State Index (discussed above).

Fish species: we conduct an annual survey of fish populations in all streams, and check for presence of trout in our designated trout streams. Fish surveys for lakes and the St. Louis River are conducted less frequently, and some of these data are included in the table.

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