Compared to Distribution

an indicator guage with the arrow in the green the value is in the best half of communities.

an indicator guage with the arrow in the yellow the value is in the 2nd worst quarter of communities.

an indicator guage with the arrow in the red the value is in the worst quarter of communities.

Compared to Target

green circle with white tick inside it meets target; red circle with white cross inside it does not meet target.

Compared to a Single Value

green diamond with downward arrow inside it lower than the comparison value; red diamond with downward arrow inside it higher than the comparison value; blue diamond with downward arrow inside it not statistically different from comparison value.

Trend

green square outline with upward trending arrow inside it green square outline with downward trending arrow inside it non-significant change over time; green square with upward trending arrow inside it green square with downward trending arrow inside it significant change over time; blue square with equals sign no change over time.

Compared to Prior Value

green triangle with upward trending arrow inside it higher than the previous measurement period; green triangle with downward trending arrow inside it lower than the previous measurement period; blue equals sign no statistically different change from previous measurement period.

green chart bars Significantly better than the overall value

red chart bars Significantly worse than the overall value

light blue chart bars No significant difference with the overall value

gray chart bars No data on significance available

Number of Miles of Phosphorus Impaired Streams

Measurement Period: 2022

The number of river miles in Marathon County impaired by high levels of phosphorus concentrations.

Why is this important?

Phosphorus is an essential nutrient for plant and aquatic life; however, elevated concentrations of phosphorus in rivers and lakes primarily from agricultural runoff can lead to nuisance algal blooms impacting aquatic life and recreational activities. High phosphorus levels cause algal blooms in Lake DuBay, Big Eau Pleine, Pentenwell and Castle Rock Reservoirs that deplete oxygen levels which stresses aquatic life and fish communities, and on occasion, cause large fish kills.

The Wisconsin Department of Natural Resources maintains a list of surface waters that do not meet specific water quality standards in the state, and is required to update the list every two years by the United States Environmental Protection Agency. The 2019 Wisconsin River Total Maximum Daily Load Report identifies the number of river miles in Marathon County considered to be impaired by high levels of phosphorus concentrations.

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