Nitrogen and Phosphorus Loading into Lake Winnipeg via the Assiniboine and Red Rivers:

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Nitrogen and Phosphorus Loading into Lake Winnipeg via the Assiniboine and Red Rivers: 1994-2001 Holer TANNER GRESCHNER

1 Nitrogen and Phosphorus Loading into Lake Winnipeg via the Assiniboine and Red Rivers: Holer TANNER GRESCHNER RILEY HOLE MEAGAN GLOWA CARRISSA LYNN KYLE-OTTENSON S U B M I T T E D A P R I L

2 TABLE OF CONTENTS 1 EXECUTIVE SUMMARY 3 2 INTRODUCTION 4 3 METHODS 7 4 RESULTS 10 5 DISCUSSION 13 6 CONCLUSION 15 7 LIST OF FIGURES 17 8 REFERENCES 18 2

3 1 EXECUTIVE SUMMARY It can be argued that Manitoba s greatest asset is the abundance of freshwater found within the province. Lake Winnipeg is the eleventh biggest lake in the world and is part of the most undeveloped watershed, which spans from Alberta to Minnesota to Northern Ontario, in Canada, yet Lake Winnipeg is one of the most threatened lakes on Earth. The escalating threat is in part the result of nutrient loading from the Assiniboine and Red Rivers, two of the major waterways feeding Lake Winnipeg. Excess nitrogen and phosphorus are being accumulated in the lake because of an intensive agricultural industry throughout the Prairie Provinces and northern states. Excess phosphorus in the lake does not allow the excess nitrogen to be absorbed, which results in large and toxic algae blooms. This report will collect and analyze data on nitrogen and phosphorus loading in the Assiniboine Rivers, based on watershed areas, from 1994 to By locating water-monitoring stations along these rivers based on their proximity to municipal, industrial and agricultural centers, samples could be collected tri-monthly so that total phosphorus and total nitrogen could be calculated for both rivers. From the data it can be seen that the Red River and including watershed contributes a larger amount of total nitrogen and total phosphorus to Lake Winnipeg annually from

4 The importance of a healthy Lake Winnipeg is vital in sustaining the economic, social and environmental security of Manitoba. We conclude our study by encouraging further, exhaustive monitoring and research on the Assiniboine and Red Rivers, which will help to understand and inhibit dangerous levels of nutrient loading into Lake Winnipeg. 2 INTRODUCTION Manitoba is home to many lakes and rivers. Surface waters account for sixteen percent of the total area of Manitoba. Some major Manitoban rivers include the Red River and the Assiniboine River. The Red River is a north flowing river that established in the bed of glacial Lake Agassiz that receded approximately eight thousand years ago. It is 877 kilometers in length and is approximately fifteen feet deep depending on the location. The Red River runs through Minnesota and North and South Dakota of the United States and into Manitoba, Canada where it connects with the Assiniboine River. The Assiniboine River is 1,070 kilometers in length and brings water from all across the prairies, as far as Figure 1: Assiniboine River Map the Rocky Mountains, and together the Red River and Assiniboine River make the Red River watershed. Both rivers empty into Lake Winnipeg through the Red River watershed and eventually flow into Hudson s Bay and become part of the Arctic Ocean. 4

Lake Winnipeg is the tenth largest freshwater body in the world and the largest hydroelectric reservoir in North America.

5 The Red River watershed collects water from approximately 280,000 square kilometers and empties it into Lake Winnipeg. There are nine major watersheds that are located in the Southern half of Manitoba with Lake Winnipeg being the recipient of the majority of the drainage from watersheds. Lake Winnipeg is the tenth largest freshwater body in the world and the largest hydroelectric reservoir in North America. It is 436 Kilometers in length and can reach depths as deep as 36 meters in some areas. Many residents in the area depend on the lake for drinking water and fish, but over the past few decades the water quality of the lake has depleted with major blame on the effects of excess nutrient loading. Excess nutrient loading is causing an increase in algae blooms on Lake Winnipeg due to an increase in nitrogen and phosphorus concentrations, which are likely associated with the inflow of nutrients from the Red and Assiniboine Rivers (Yi, Y, Gibson, J, Helie, JF, Dick, T, 2010). Nutrient loading in lakes and rivers is an important issue in water quality. Excess nutrients in water can lead to increased algae and aquatic plant growth which produce toxins that can cause off tastes and odors, and decrease biodiversity in the water (Mayer, B, Wassenaar, L, 2012). Two important nutrients that are involved in nutrient loading are Nitrogen and Phosphorus. [Fig. 2] Algae Blooms on Lake Winnipeg Both of these nutrients are essential to plant growth. Phosphorus is needed in the process of photosynthesis and nitrogen is 5

6 an essential nutrient for all living organisms. Nitrogen and phosphorus can contribute to nutrient loading in lakes and rivers in many different ways, either through anthropogenic sources or naturally. Some anthropogenic contributions to nutrient loading could include factories or agricultural processes that result in effluent discharge into nearby water sources (Schindler, D, Hecky, R, McCullough, G (2012). In Manitoba fifteen percent of the land is used for agricultural activities. Fertilizers are commonly used in agriculture, which can increase the potential for nutrient loading to surface waters in surrounding areas due to runoff. Surface runoff from non-fertilized fields can also be a problem due to naturally rich soils. There are fourteen rivers in Manitoba, including the Rat River and Morris River, that drain farmland on the east and west side of the Red River Valley into the Red River. A natural process that could contribute to nutrient loading would be rain. Nitrogen and Phosphorus could be directly deposited on land and water by rain. Nitrogen and Phosphorus can also be found in sediment particles in streams. The particles can be picked up by the current and moved further downstream changing the concentration of nutrients in the stream. A brief introduction of the calculations for nitrogen and phosphorus found in water samples is described below. Total phosphorus concentrations (TP) and total nitrogen concentrations (TN) are used as the measurement for phosphorus and nitrogen respectively. Total phosphorus is not an indication of the amount of phosphorus present in a sample of water but rather a measurement of the amount of phosphorus that is potentially available to plants in the water. To determine TP the dissolved and particulate forms of phosphorus are added together, and to determine TN it is the combination 6

7 of total organic nitrogen (TON) and total inorganic nitrogen (TIN). TON is found by measuring the total Kjeldahl nitrogen content (TKN), which consists of TON and ammonia, so by subtracting the ammonia from TKN you are left with the measurement for TON. TIN is simply found by adding together the ammonia concentrations and the nitrite-nitrate concentrations in a water sample. The total measured stream nutrient load (TMSNL) calculates the amount of nutrients present in a stream at a given time. Processes that directly influence TMSNL are referred to as within-stream processes, such as erosion, and processes that indirectly influence TMSNL are referred to as watershed processes, such as runoff. To calculate TMSNL the nutrient concentration of the stream is multiplied by the flow rate of the stream in a particular area. The focus of this experiment is placed on the Red River watershed. Nitrogen and phosphorus concentrations are found for both the Red River and the Assiniboine River between the years of 1994 to 2001 to determine whether the Red River and the Assiniboine River contribute different amounts of nutrients in the form of nitrogen and phosphorus per square kilometer to the Red River watershed, and in turn to Lake Winnipeg. 3 METHODS Several permanent water Monitoring stations were selected along the Assiniboine River and the Red River. The maps [Fig. 3,4] show where stations were located throughout the two rivers. The population to be sampled was nitrogen and phosphorus load in the two rivers, the sampling frame being all water within the 7

8 Assiniboine and Red Rivers. The decision of where water-monitoring stations were placed was based on a non-probability, convenience-sampling method due to variability in river geography. Stations were also set up based on proximity to agricultural land, areas of municipal and industrial effluent and other sites that have varying effects on nitrogen and phosphorus load within the two rivers. Sampling for the two rivers went as followed; during months when the two rivers were not frozen over (May November) samples were collected three times monthly through the use of these water sampling stations. At these stations water is collected approximately 2-3 meters from the river bottom using a thoroughly cleaned and rinsed plastic bucket. Water was then placed in four bottles and was taken to a lab to be analyzed for total nitrogen and total phosphorus load (mg/l). Monthly data was kept on record in the lab. During months when the two rivers were frozen (December April), holes were drilled through the ice using an auger and water samples were extracted though these holes using four thoroughly cleaned and rinsed plastic bottles. Samples were also collected three times monthly. Total nitrogen and total phosphorus (mg/l) were measured and recorded as it was in the non frozen months and data records were kept on file. This sampling process continued consistently from 1994 to From this collection of monthly data throughout the years, annual averages were calculated for total phosphorus and total nitrogen load in the Assiniboine River and the Red River separately. 8

9 [Fig. 3] Red River water quality monitoring stations ( ). Gov [Fig. 4] Assiniboine River water quality monitoring stations ( ). Gov

10 4 RESULTS In order to obtain values of some significance, data had to be combined. Data was supplied in the form of tons per year of either phosphorus or nitrogen nutrient. We wanted to focus on the total value of eutrophication causing nutrients that enter Lake Winnipeg via the Red River and Assiniboine River. In order to obtain these values we had to add the total nitrogen load from 1994 to 2001 to the total phosphorus load for the same time frame. [Fig. 5] below displays the total phosphorus and nitrogen loads for each station along the two rivers and for each year, starting at 1994 and ending at The figure also displays the mean and standard deviation of the total nutrient levels present in both the Red and Assiniboine rivers. Total TN and TP (t/year) Assiniboine River Mean s At Kamsack At Brandon At Treesbank At Portage Spillway East of Portage At headingley Red River At Emerson At St. Norbert At Selkirk [Fig. 5] Total nutrient loading for gauging stations along the Assiniboine and Red Rivers The best estimate for the two separate nutrient loads should be compared before the two rivers merge at the Forks in Winnipeg Manitoba. The last gauging station before the Assiniboine meets the Red River is at the Headingly location approximately 21.5 kilometres according to Google Maps. The last station on the 10

11 Red River before it merges with the Assiniboine River is at the St. Norbert gauging station, which is approximately 16.5 kilometres from the Forks also calculated by Google Maps. The readings from these two gauging stations where used to conduct the proper tests. It makes sense that the gauge stations up stream have smaller nutrient loads, Kamsack station is the furthest station up the watershed the values are lower than other stations because less accumulation of nitrogen and phosphorus nutrients has taken place. There is a wide inter-annual variation between the amounts of nutrient load in the two rivers. The range in load amount for the Assiniboine River is 4474 tons of nutrients, with 1994 having the smallest value 2,050 tons and 1999 with the largest amount of nutrients at 6,524 tons. The Red River carries a significantly larger load of nutrients, the lowest amount occurred in 2000 at 18,271 tons. The largest amount of nutrients occurred in 2001 with a mass of 45,099 tons giving the red a range of 26,828 tons. From the combined total phosphorus and total nitrogen amounts it is clear that there are more nutrients flowing into Lake Winnipeg that originated in the Red River. The purpose of our test was not to look at the amounts of the nutrients but to look at the nutrients per square kilometer of each rivers total watershed area. Calculated in previous work the total watershed area for the Assiniboine River is equal to 41,500km 2, and the watershed area for the Red River was 127,000km 2 (Bourne). With this information further statistics could be derived to calculate nutrient amounts per square kilometer for each watershed. The data is presented below in [Fig. 6]. TN&TP loads/km Assinaboine Red River [Fig. 6] Tonnes of nutrients per watershed area, at the last two gauging stations for each river. 11

12 The data above in figure 2 represents the total tonnes of nutrients per square kilometer of the respective watershed area. In order to compare the results of the data in figure 2, a program by the name of Statistical Product and Service Solutions (SPSS) was used. The data entered in the SPSS program is available for analysis and interpretation. A paired sample t-test was run in SPSS to acquire the correct information about the gathered data. The test contains a 95% confidence interval and a significance value of The results of the test run are located below in [Fig, 7]. [Fig. 7] SPSS results From figure 3 above we are interested in one of the values; we are interested in the Sig. (2-tailed) value or p-value as commonly referred to. Stated earlier in the paper we predict that the Red River and the Assiniboine River will contribute the same amount nutrients in the form of nitrogen and phosphorus per km 2 of the watershed between the years of 1994 to To test if this hypothesis is correct we need to interpret the p-value, if the p-value is less than the significance value (α) then there is enough evidence to reject the null hypothesis. The p-value for our test is a very 12

13 small number less than 0.000, this means that our p-value is less than α (0.05). This means that we reject the null hypothesis that the Red and Assiniboine River contribute the same amount nutrient mass to Lake Winnipeg in the form of nitrogen and phosphorus per square kilometer of the watershed than the Assiniboine River. To understand this fully there is sufficient evidence to support that the Red River and Assiniboine River contribute the different amounts of nutrients per square kilometer to Lake Winnipeg. 5 DISCUSSION Nitrogen is a naturally occurring nutrient that is used and reused by plants in an ecosystem with minimal leakage into surface and ground water. When nitrogen is applied to land in amounts greater than the amount that can be used by crops, concentrations in rivers tend to increase. Excess nitrates are not toxic but they can result in large algae blooms, which can decrease oxygen levels, consequentially harming fish and other aquatic life. Animal waste, septic systems and atmospheric deposition, as well as fertilizer, contribute to excess nitrogen. Saturated phosphorus levels in water systems can also lead to over stimulated algae growth. It is important to look at the factor of nutrient loading in the rivers that lead to major lakes. When you look at the dispersion of where nitrogen and phosphorus enter Lake Winnipeg it makes interpreting the amount of these two nutrients 13

coming from the Red River. [Fig. 8] below shows the amount of total nitrogen on the right and total phosphorus entering Lake Winnipeg from each respective source. [Fig. 9] Mean TN & Mean TP [Fig.

14 coming from the Red River. [Fig. 8] below shows the amount of total nitrogen on the right and total phosphorus entering Lake Winnipeg from each respective source. [Fig. 9] Mean TN & Mean TP [Fig.8] illustrates the importance of understand the aspects that lead to the large amount of nutrient addition to the lake via the Red River, and the Assiniboine River is a critical part of the Red River. Lake Winnipeg was named the most threatened lake of the year by an international environmental organization from Germany called Global Nature Fund (Radolfzell, 2013). It got this title due to increasing pollution amounts from agricultural run-off and sewage discharges. The pollution, in turn, creates an overabundance of phosphates, which results in the formation of blue-green algae, which are toxic to humans and throw the lake's ecosystem offbalance. There is great need to understand the workings of the lake and all factors that lead to the nutrient loading of the rivers that lead to the lake. 14

15 6 CONCLUSION Based on the findings of our study we strongly recommend continued research regarding nitrogen and phosphorus loading into Lake Winnipeg via the Assiniboine and Red Rivers, enabling the Manitoba government to develop a provincial and national strategy to decrease hazardous nutrient loading into the worlds eleventh largest freshwater lake. Agricultural, industrial and municipal activity all contributes to this problem. Their activity must be controlled and accounted for, as to not further damage the volatile Lake Winnipeg. The US state of Florida has began to implement a strategy to reduce nitrogen and phosphorus loading in their waterways by introducing a water quality credit trading program (Florida DofEP, 2010). The program is similar to the European Unions Emission Trading System where emission allowances can be bought or sold by traders. Another strategy is being implemented by the state of Iowa to reduce nutrient loading into the Gulf of Mexico via the Mississippi River and it s Iowan watershed. The state has set up the Water Resources Coordinating Council to help centralize water quality strategies and one of their first objectives is to determine goals the state wants to achieve in reducing harmful activity in watershed areas. Iowa intends to technologically advance their wastewater treatment plants by utilizing the National Pollutant Discharge Elimination System permit process (Iowa Department 15

16 of Agriculture and Land Stewardship, 2012). The state is also focused on prioritizing initiatives in research, technology, education and public recognition to maximize their potential to reduce nutrient loading. Since the mid-1980s Denmark has also been setting specific reduction targets and innovative strategies to reduce nitrogen and phosphorus loading. It is clear this issue is a global one and has the attention of major world leaders. Since Manitoba has such an abundance of freshwater at risk it is important that the government takes major strides to become a national and global leader in water quality initiatives and innovations. 16

17 7 LIST OF FIGURES FIGURE 1 Bower, S (May ). The Assiniboine River Flood of 2011: Without Precedent. Retrieved on April from: FIGURE 2 Science Daily (July ). Trying To Save World's Lakes: Controlling Nitrogen Can Actually Worsen Problems. Retrieved on April from: FIGURE 3 Bourne, A, Armstrong, N, Jones, G (November 2002). A Preliminary Estimate of Total Nitrogen and Total Phosphorus Loading to Streams in Manitoba, Canada. Retrieved on March from: ww/mc_nitrophosload.pdf FIGURE 4 Bourne, A, Armstrong, N, Jones, G (November 2002). A Preliminary Estimate of Total Nitrogen and Total Phosphorus Loading to Streams in Manitoba, Canada. Retrieved on March from: ww/mc_nitrophosload.pdf FIGURE 5 SPSS Data - Total nutrient loading for gauging stations along the Assiniboine and Red Rivers FIGURE 6 SPSS Data - Tonnes of nutrients per watershed area, at the last two gauging stations for each river FIGURE 7 SPSS Data Paired Samples Test FIGURE 8 SPSS Data Total TN & Total TP 17

18 8 REFERENCES Yi, Y, Gibson, J, Helie, JF, Dick, T (2012). Estimating nutrient production from human activities in sub catchments of the Red River. Journal of Hydrology [Vol.383, p ] Mayer, B, Wassenaar, L (2012). Isotopic characterization of nitrate sources and transformations in Lake Winnipeg and its contributing rivers. Journal of Great Lakes [Vol.38, p ] Schindler, D, Hecky, R, McCullough, G (2012). The rapid eutrophication of Lake Winnipeg: Greening under global change. Journal of Great Lakes Research. [Vol. 38, p.6-13] Bourne, A, Armstrong, N, Jones, G (November 2002). A Preliminary Estimate of Total Nitrogen and Total Phosphorus Loading to Streams in Manitoba, Canada. Retrieved on March from: ww/mc_nitrophosload.pdf Armstrong, Nicole. "ASSINIBOINE RIVER WATER QUALITY STUDY." Manitoba conservation (2002): river_water_quality_report_2002_10.pdf. Web. 7 Apr Radolfzel (February ). Global Nature Fund. Threatened Lake of the Year 2013: Lake Winnipeg in Canada. Retrieved on March 15, 2013 from: Florida Department of Environmental Protection (October 2010). Pilot Water Quality Credit Trading Program for the Lower St. Johns River. Retrieved on March from: pdf Iowa Department of Agriculture and Land Stewardship (November 2012). IOWA NUTRIENT REDUCTION STRATEGY: A science and technology-based framework to assess and reduce nutrients to Iowa waters and the Gulf of Mexico. Retrieved on March from: f 18

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Nutrients and Water Quality in the East Souris River Watershed

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