Water Quality of Major Lakes in MFCRWD

The  Middle Fork Crow River Watershed District  (MFCRWD) was established in 2005 to protect and preserve water quality within the watershed. The Middle Fork Crow Watershed drains about 271 square miles.

The MFCRWD partners with the North Fork Crow River Watershed District to conserve water quality through water monitoring, land use planning, and carrying out water resource management projects.

This study goes into depth of water quality of the major lakes within the MFCRWD: Green, Monongalia, Long, Calhoun, Nest, George, Elkhorn, and Diamond. To better understand this, Total Phosphorus (TP), Total Suspended Solids (TSS), Chlorophyll-a (Chl-a), and Secchi Readings are indicators that can be used to analyze issues and find possible solutions.

To better understand water quality, watershed technicians and volunteers can go out to bodies of water and collect data. Some of the main measurements taken that will be used within this study are Total Phosphorus (TP), Total Suspended Solids (TSS), Chlorophyll-A (Chl-a), and Secchi readings. These readings can be interpreted as:

• Total Phosphorus measures phosphorus and is often found in wastewater treatment. In appropriate quantities, phosphorus can be used by vegetation and soil microbes. However, excess can lead to water quality problems, such as eutrophication and harmful algal growth, which will eventually need to be removed.
• Total Suspended Solids indicates quality of any water specimen. TSS absorb light, causing increased water temperature and decreased oxygen, creating unfavorable environment for aquatic life
• Chlorophyll-a is used to measure the amount of algae growth in waterbody and classify the eutrophic condition of waterbody. High amounts of chlorophyll-a can lead to an increase in turbidity and murky water
• Secchi readings measure transparency or turbidity in bodies of water. This is done by placing the disk into a shaded area and lowering it into the water until it cannot be seen. Transparency can be impacted by the color of the water, algae, and sediments

For each of the main lakes, there are specific monitoring locations were Middle Fork staff or community volunteers measure temperature, conduct secchi readings, and take water samples. The map below shows the specific monitoring sites on each of the lakes: Green, Monongalia, Long, Calhoun, Nest, George, Elkhorn, and Diamond.

Total Phosphorus is measured by the amount of micrograms per liter, or the concentration of phosphorus in water. Nutrients are a natural part of healthy lakes, rivers, streams, and ecosystems with plant growth. However, excess TP can lead to water quality issues and harmful algae blooms.

Waterbodies within the MFCRWD area must follow chemistry standards in the Northern Central Hardwood Forest ecoregion. The phosphorus criteria for our lakes is at or below 40 ug/L.

Image 1 (pictured left) depicts the 2023 Average Phosphorus Levels of the Major Lakes in the Middle Fork Crow River Watershed District. Green Lake has the lowest phosphorus average of 13.2 ug/L, Long and George range from 13.3 to 14.2 ug/L, Calhoun and Elkorn range from 14.3-22.4 ug/L, Nest and Monongalia range from 22.5-30.6, and Diamond has the highest phosphorus levels of 72.0 ug/L. Since Green, Long, George, Calhoun, Elkorn, Nest, and Monongalia have levels below 40 ug/L, they meet the Minnesota water quality standard of phosphorus. However, Diamond does not due to having an average TP level of 72 ug/L.

Total Suspended Solids measures suspended, undissolved particles in a sample of water. TSS is also measured by the amount of micrograms per liter. Sediments can be a major source of the plant nutrients phosphorus, nitrogen, and iron. Excess nutrients can stimulate higher algae and plant growth, which can lead to water quality issues. There is concern with excess TSS because it can clog fish gills and can settle to the bottom of water and cover fish eggs and hatcheries, and invertebrate habitats.

Minnesota does not have a Total Suspended Solids criteria range, but the Central River Nutrient Region standard for total suspended solids is less than 30 milligrams per liter (mg/L). According to Image 2 (depicted right), all lakes have TSS levels of below 30 mg/L. Even though MFCRWD Lakes do not have extreme excess of TSS, these levels can still contribute to overall water quality.

Total Chlorophyll-a measures the primary productivity of a water system, or the measurement of growing algae within a body of water. Chlorophyll-a is a well known bioindicator of eutrophication levels of lakes, which measure the overall productivity of lakes, since it is the most common photosynthetic pigment in plants and algae. Like phosphorus and suspended solids, a healthy balance of Chlorophyll-a is important in lakes. Algae is the base of a lake's food web. Without algae, organisms higher up the food chain would not survive. It is also common for Chlorophyll levels to fluctuate over time due to rain, temperature, and access to sunlight.

Excess levels of chlorophyll cause aesthetic issues regarding green scums and unpleasant odors. This can also result in decreased levels of dissolved oxygen, which can cause death of aquatic species. Chlorophyll also has the potential to harm humans.

Shown in Image 3 (right), George and Elkhorn have the lowest Chl-a levels, Green has the second lowest, Long and Calhoun are in the middle at 4-6 ug/L, Monongalia and Nest have the second highest levels, and Diamond Lake has the highest levels of Chl-a. According to the Minnesota Pollution Control Agency and Specific Water Quality Standards of Class 2 Waters within Minnesota, an ideally safe amount of Chlorophyll-a in water bodies is anything less than 14 ug/L in deep lakes (over 15 feet deep) and less than 22 ug/L for shallow lakes (less that 15 feet deep). Using this information, all lakes except for Diamond Lake have safe average levels of Chlorophyll-a.

Secchi disks and tubes are used to measure the transparency of water (in units of feet). Secchi measurements can be impacted by algae, sediments, and water color. To do this, the disks are places into the water and lowered until it cannot be seen. Secchi depth refers to water clarity and how far light travels through water.

Image 4 (shown left) shows the 2023 Average Secchi Depth of Major Lakes in the Middle Fork. This map shows which lakes have shorter and longer Secchi depths. For example, George Lake and Elkhorn Lake have Secchi depths ranging from 11.5 - 17.3 feet. This indicates that the water is clearer and light penetrates the water relatively far. Meanwhile, Diamond, Monongalia, and Nest Lakes have a shorter Secchi depth, meaning the water is more turbid and light does not pass through the water as easily. Minnesota Specific Water Quality Standards for Class 2 Waters require secchi disk transparency of 4.6 feet. Knowing this information, all lakes, except Diamond, meet this standard.

These results show the amount of nutrients within bodies of water and possible impacts upon them. Nutrients within water does not mean that the lake has poor water quality. However, an imbalance or excess of nutrients can lead to water quality issues. There are so many aspects that impact water quality, this is just a glimpse into some of the factors.

Water quality is crucial because it is one of the most important components to a healthy ecosystem. We use water quality to better understand the conditions of the water, biological characteristics, and the suitability of whether it can be used for drinking or recreational uses.

And although water seems abundant, only 3% of Earth's water is freshwater. Only 0.3% of this is comprised of lakes and rivers, the rest can be found frozen in glaciers or in groundwater.

Water is easily susceptible to contamination. A common misconception about stormwater runoff is that it drains through a filtration system. Runoff actually drains directly into our rivers and streams which drain into larger water bodies. Throughout this process, the water picks up debris, chemicals, dirt, and other pollutants.

This polluted runoff contaminates the water used for drinking and recreational purposes, and can have negative impacts on humans, wildlife, and plants.

• Pick up litter and dispose of it properly.
• Clear out debris from around stormwater drains
• Do not blow grass clippings or leaves into the street. Yard waste can easily be composted or left to provide shelter for invertebrates.
• Wash cars and outdoor equipment to where runoff can flow into grass or gravel.
• Be mindful with fertilizer application to prevent pollution.
• Compost food scraps rather than using the garbage disposal in your sink.
• Conserve your water use.
• Use alternatives to salt on icy surfaces.
• Green Agriculture - emphasizes water conservation and efficient management practices. Several types of technologies are used to optimize water in sustainable farming.
• Wetland Practices - practices that are implemented to help protect wetlands. Wetlands function to improve water quality, control erosion, and store water.
• Spread awareness about the importance of water quality.