The Nemadji River and Deer Creek Total Maximum Daily Load Study
Total Maximum Daily Load (TMDL) is a study to determine the maximum amount of a pollutant that a body of water can accumulate while still meeting water quality standards. Samples are taken and analyzed to determine the health of the body of water. Then it is compared to the EPA’s water quality standards. If the body of water does not meet those standards it is put on the 303(d) impairment list. BMP’s are then implemented to create a healthy water body.
The Nemadji River and Deer Creek are on the impaired waters list under section 303(d) of the Clean Water Act for turbidity. Both are being assessed for turbidity through a TMDL. This is only one step in a multi-step processes in order to lead to a healthier creek. Data gathering through the TMDL will tell us where turbidity is highest. Then based on the results we will determine where BMP are most needed to create healthier water.
During the assessment period, the water quality is determined from the data gathered. This data includes; temperature, dissolved oxygen, pH, specific conductivity and water samples. The water samples are sent to a lab to be analyzed for turbidity, phosphorus, orthophosphate, kejhidal nitrogen, nitrates, total suspended solids, and total volatile solids.
Temperature – affects both the chemical and physical aspects of water. Temperature directly correlates with the dissolved oxygen. The colder the temperature correlates with more dissolved oxygen. Temperature affects they physical aspect of water through the different biology that can live in that environment. For instance trout live in colder waters.
Dissolved Oxygen – affects the biology within the water. The more water allows for more algae to photosynthesis. Then once the algae die, bacteria decompose the algae using up oxygen. This is a process known as hypoxia. Hypoxia is a lack of oxygen in the water making it difficult for organic life to live in the water.
pH – is measure on a scale between 0-14 with 7 being neutral. Values trending toward 0 are more acidic and values trending toward 14 are more alkaline (basic). pH measures the solubility and availability of nutrients (such as phosphorus and nitrogen) and metals (such as lead and copper).
Specific Conductivity – is the measure of how well the water conducts electricity. This is dependent upon the amount of particles floating in the water. A high specific conductivity correlates with a high amount of dissolved particles. The more particles in the water then can lead to a higher temperature as the particles will absorb the suns radiation ultimately heating up the water.
Turbidity – looks at the amount of sediment particles in the water by measuring the displacement of light due to the particles. A high turbidity means a larger amount of scattered light causing the water to look murky and opaque.
Phosphorus – is known as the limiting nutrient for plant growth. Therefore phosphorus also can lead to hypoxia. Phosphorus comes from fertilizers that run-off into water and from bank erosion.
Orthophosphate – is a form of phosphorus used most commonly by plants. This leads to hypoxia as well.
Kjehidal Nitrogen – Kjehidal is a method of measuring a nutrient. In this case this is a measures the sum of ammonia and organic nitrogen. this has the potential of leading to hypoxia.
Nitrites (nitrate and nitrite) – These forms of nitrogen commonly come from fertilizers and waste. They are a macronutrient and lead to abundant plant growth potentially causing hypoxia.
Total Suspended Solids (TSS) – This measures the amount of particles in the water. This differs from turbidity in that it will measure the weight of the solid particles. These particles will enter into a body of water through erosion and run-off.
Total Volatile Solids – is the measurement of the organic matter in the residue from TSS.
Below are the water quality standards for these parameters divided into drinking water, Stream/Rivers and Lakes.
|List of Data and There Corresponding Water Quality Standards|
|Turbidity||5 NTU||25 NTU||10 NTU|
|Phosphorus||5 mg/L||30 ug/L||30 ug/L|
|Orthophosphate||5 mg/L||30 ug/L||30 ug/L|
|Nitrates (nitrate and nitrite)||10 mg/L||10 mg/L||10 mg/L|
|Total Suspended Solids||32 mg/L||32 mg/L||32 mg/L|
|Total Volitile Solids||n/a||n/a||n/a|
Deer Creek and Nemadji River Studies begin.
Why is the water always brown? How harmful can that be? County residents have always been interested in their water resources and to answer these questions and more Carlton County Soil and Water Conservation District, in partnership with Minnesota Pollution Control Agency, has begun work on the Deer Creek/Nemadji River Total Maximum Daily Load (TMDL) study. Previous watershed studies identified high turbidity and sediment as significant impacts to water quality. The result of these studies was to “list” Deer Creek and Nemadji River on the Federal Clean Water Act (303) d list of impaired waters. An impaired waters designation requires completion of a TMDL study.
Turbidity or cloudiness of the water, and high sediment yields can be detrimental to fish and other aquatic life, and in this case, even shipping! Sediment degrades the quality of the spawning habitat and turbidity can affect feeding success. High sediment loads from the Nemadji River have also been a major contributor to sediment buildup in the Superior Harbor. Historically, about 33,000 tons of Nemadji River sediment has been dredged annually from Lake Superior Bay by the U.S. Army Corps of Engineers to maintain adequate depth for shipping traffic.
The TMDL process will complete a series of steps to ultimately define a “load” or the maximum amount of pollutant (in this case sediment) that a water body (Deer Creek and Nemadji River) can receive and still meet state water quality standards. Sources of sediment are identified along with the amount of reduction needed. Strategies for reducing sediment will be investigated and described in an implementation plan. The eventual goal is to reduce sediment sources such that all contributions will result in Deer Creek and Nemadji River meeting water quality standards.
Deer Creek was monitored for water quality by the Carlton SWCD during the Nemadji River Basin Project in 2001-2002. Total Suspended Solids (TSS) and other water quality data was collected to determine baseline conditions of the stream. The Minnesota Pollution Control Agency (MPCA) reviews water quality data collected by carious agencies in order to determine if the stream conditions meet or exceed water quality standards. A Professional Judgment Review Team determined that Deer Creek exceeds the state water quality turbidity standard of 10 NTU for class 2A (cold water trout waters) based on the TSS data collected in 2001-2002. According to the MPCA’s Guidance Manual for Assessing the Quality of Minnesota’s Surface Waters, the MPCA has not analyzed enough data on class 2A waters to determine a transparency tube or TSS threshold for violation of the 10 NTU turbidity standard. The determination of impairment for Deer Creek is based on 40 out of 40 exceedances of the TSS/Turbidity relationship developed from the North Shore Streams data set. The graph below displays the Deer Creek TSS dataset from 2001-2002.