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“Many of the world’s saline lakes are shrinking at alarming rates, reducing waterbird habitat and economic benefits while threatening human health.”
So begins a recent report in Nature Geoscience.
Saline lakes, also known as salt lakes, are landlocked bodies of water with a concentration of dissolved minerals several times higher than in freshwater lakes, sometimes even higher than in the ocean. The largest in the world is the Caspian Sea, but other well known saline lakes include the Dead Sea and the Great Salt Lake. Two dozen of the world’s most important saline lakes are shown in Figure 1. The larger blue dots indicate those that formerly had a surface area larger than 250 square kilometers (larger than a circular lake about 18 miles across).
Wayne Wurtsbaugh and his associates looked at the volume of water in 6 saline lakes. The sample is loaded towards the United States, but includes two in Central Asia:
- The Aral Sea (Kazakhstan and Uzbekistan)
- The Dead Sea (Israel, Jordan, and Palestine)
- The Great Salt Lake (Utah, United States)
- Lake Urmia (Iran)
- Owens Lake (California, United States)
- Walker Lake (Nevada, United States)
Figure 2 shows the loss of water in the 6 lakes over time, with some lakes going back to 1875. Every one of them has experienced a dramatic loss.
The Dead Sea has experienced the lowest percentage loss, the reason being that it is a very deep lake (Maximum depth 978 ft.) Despite that fact, the surface of the lake has dropped 28 feet, and it has been divided in two. (Wikipedia 2018b, Wurtsbaugh et al, 2017).
Starting in 1913, the streams that fed Owens Lake in California were diverted to provide water to Los Angeles. (See my post on California’s water supply, here. For movie buffs, this is also the subject of the famous movie Chinatown.) The lake has been almost completely drained, and is now mostly a dry lake (salt flat). (Wikipedia 2018c)
Perhaps the “poster child” for what can happen to dry lakes is the Aral Sea. Formerly one of the largest lakes in the world, with a surface area of 26,300 square miles (almost the size of Lake Superior), water diversion has turned it into several small lakes, plus a whole lot of dry lake bed (salt flat). Figure 2 shows the Aral Sea in 2014, with the gray line showing the former extent of the lake. (Micklin 2007, Wikipedia 2018a, NASA 2014)
The demise of these lakes has not been caused primarily by a decline in precipitation, but rather by diversion of water for human consumption. In some cases, the consumption has been to provide potable water for large population, as in the case with Owens Lake and Los Angeles. In other cases, it has been to provide irrigation water for crops, as in the case with the Aral Sea.
Many aquatic species live in saline lakes, and the lake’s demise obviously devastates them. In addition, the survival of many species of migratory birds depends on an unbroken chain of places they can stop and refuel on their long journeys. Break the chain in even one place, and their survival is threatened. Saline lakes are one of the places birds stop during migration, and draining the lakes threatens to break the chain.
In addition, when saline lakes are emptied, what remains behind is a fine, salty dust that is laced with heavy metals and pesticide residue that drained into the lake over many years. It is picked up by the wind and blown for miles. Posts in this blog have discussed the health threats represented by airborne particulates, and the damage done by this salty dust has been well documented around the Aral Sea. Aerial photographs revealed salt plumes extending as much as 500 km. (310 miles) from the lake. It is considered an essential factor in the region’s high incidence of both acute and chronic illness. (Micklin 2007)
Of these lakes, the 2 with the highest percentage of remaining water are the Dead Sea and the Great Salt Lake. Wurtsburgh et al conclude that the key to conserving these lakes is to provide the river inflow needed to restore and sustain them. Otherwise, these once important lakes will remain (become) nothing but a choking dust in the wind.
Micklin, Philip. 2007. The Aral Sea Disaster. Annual Review of Earth and Planetary Sciences. 35:47-72. Available online at http://www.annualreviews.org/action/doSearch?SeriesKey=earth&AllField=Micklin&startPage=&ContribAuthorStored=Micklin%2C%20Philip.NASA. 2014.
NASA. 2014. ”The Aral Sea Loses Its Eastern Lobe.” Earth Observatory. Downloaded 2018-01-04 from https://earthobservatory.nasa.gov/IOTD/view.php?id=84437.
Wikipedia. 2018a. “Aral Sea.” Wikipedia. Viewed online 2018-01-04 at https://en.wikipedia.org/wiki/Aral_Sea.
Wikipedia. 2018b. “Dead Sea.” Wikipedia. Viewed online 2018-01-04 at https://en.wikipedia.org/wiki/Dead_Sea.
Wikiepedia. 2018c. “Owens Lake.” Wikipedia. Viewed online 2018-01-04 at https://en.wikipedia.org/wiki/Owens_Lake.
Wurtsbaugh, Wayne, Craig Miller, Sarah Null, Justin DeRose, Peter Wilcock, Maura Hahnenberger, Frank Howe, and Johnnie Moore. 2017. Nature Geoscience, Vol 10. DOI: 10.1038/NGEO3052. Available online at www.nature.com/naturegeoscience.
Southwest Missouri faces a water crisis. If nothing is done, demand will exceed current supply by 2030. However, sufficient additional water to meet demand through 2060 appears to be available, and could be accessed at a relatively low cost. Whether doing so would impact the regions ecosystem is not known.
In the previous post, I reported that current stresses on water supply along the Missouri River depend primarily on human decisions about how to manage competing demands for the river’s water. The future effects of climate change are not yet known.
What about regions of the state that don’t depend on the Missouri River for their water supply? Are demands projected to exceed supply?
To answer that question, we must start by distinguishing between water resources and water supply. Water resources consist of the total water available in a region. Water supply is the amount of water that the infrastructure is capable of delivering.
Water resources consist of surface water and groundwater. Some regions of the state depend primarily on surface water. In fact, surface water supplies 8 of Missouri’s 10 largest cities, and 62% of the state’s total water consumption (44% from the Missouri River alone). Groundwater supplies about 38% of Missouri’s water consumption. Some regions, however, rely more heavily on groundwater, especially in the southern part of the state.
No region of the state is currently experiencing a sustained shortfall in water supply compared to demand. Perhaps the region most likely to experience one in the future is a 16 county area in Southwest Missouri. Figure 1 shows a map of the 16 counties.
The region has historically depended primarily on groundwater, as it is underlain by the Ozark Aquifer. Aquifer levels fluctuate depending on how much precipitation occurs to recharge them. In addition, over-pumping can deplete the water supply in a local region of the aquifer faster that water can flow in to replace it, causing a cone of depression. It can leave neighboring wells high and dry, but does not affect the whole aquifer. Severe over-pumping from multiple sources can deplete the entire aquifer, which is occurring in California.
The region’s constraints on water supply have occurred because of growth. Figure 2 is a map of population density in Missouri. It shows that Southwest Missouri is one of the more densely populated regions.
Figure 3 shows that from 1990-2000 the region was the fastest growing in the state. Between 2000 and 2010, the trend continued, with Christian County growing an astounding 43% and Taney County growing by 30%.
The result has been over-pumping, and Figure 4 shows the results. In Southwest Missouri, most areas have experienced some decrease in the groundwater level. A few regions in Green County (the City of Springfield), Jasper County (the City of Joplin), and Stone and Taney Counties (the Branson area) have experienced cones of depression, dropping the water table more than 300 feet. The worst affected area is the large red area on the left side of the map. It is in Oklahoma, centered on Miami, OK.
Using a mid-level growth forecast, studies have calculated that current water resources will be overrun by demand by 2030. Even reducing demand through conservation would only meet needs through 2040.
The region has significant surface water resources, however, and could supplement its water supply. Three significant reservoirs could supply water to the region: Stockton Lake, Table Rock Lake, and Lake Taneycomo. The first two are operated by the U.S. Army Corps of Engineers, and the latter is owned and operated by Empire District Electric Company. These organizations would have to approve the reallocation of water, but the water is there. Figure 5 shows projected available supply and demand if surface water resources were tapped. It would require the construction of pipelines and pumping stations, but the dams and reservoirs already exist.
Climate change is not projected to cause a decrease in precipitation in the region. The worst drought on record occurred in the 1950s, and if anything, the trend in precipitation has increased slightly since 1895. The temperature is projected to increase significantly, however. If increased temperature were to lead to less water reaching the aquifer to recharge it, then it could have implications for the regions water supply. But so far, those projections have not yet been calculated.
Unfortunately, none of the reports I contacted discuss the environmental impacts that the increasing demand for water will place on the ecosystem in the region. In fact, so far as I could tell, possible effects were not even considered. Will dropping water tables cause springs, creeks, and rivers to go dry? Will reallocation of the water from the regions reservoirs affect the health of the White and Osage Rivers? Will subsidence occur? These effects have occurred elsewhere, why Missouri would expect to be immune from them? But I just don’t know.
Thus, it appears that Southwest Missouri does face a water crisis. If nothing is done, demand will exceed current supply by 2030. However, sufficient additional water to meet demand through 2060 appears to be available, and could be accessed at a relatively low cost. Whether doing so would impact the regions ecosystem is not known.
Missouri Department of Natural Resources. Springfield Plateau Groundwater Province. Downloaded 5/23/2017 from https://dnr.mo.gov/geology/wrc/groundwater/education/provinces/springfieldplatprovince.htm?/env/wrc/groundwater/education/provinces/springfieldplatprovince.htm.
State of Missouri and U.S. Army Corps of Engineers. 2012. Southwest Missouri Water Resource Study – Phase I. Downloaded 5/23/2017 from http://www.swl.usace.army.mil/Portals/50/docs/planningandenvironmental/Phase%20I%20-%20Southwest%20Missouri%20Water%20Study%20Final%20Report%20.pdf.
State of Missouri and U.S. Army Corps of Engineers. 2014. Southwest Missouri Water Resource Study – Phase II. Downloaded 5/23/2017 from http://tristatewater.org/wp-content/uploads/2014/11/Phase-II-FINAL-Southwest-Missouri-Supply-Availability-Report-Final_March_2014-from-Mike-Beezhold-9-16-14.pdf.
Tri-State Water Resource Coalition. 2015. Securing Water for Southwest Missouri. Downloaded 5/30/2017 from https://waterways.org/wordpress1/wp-content/uploads/2015/05/Securing-Water-for-Southwest-Missouris-Future.pdf.
How climate change will affect water supply from the Missouri River is not yet known. Current problems with Missouri River water supply principally affect the barge transportation industry, and the agricultural and industrial clients that use it to transport their goods and supplies.
The Missouri River is important for Missouri. More than half of Missouri residents get their drinking water from the Missouri River or the alluvial aquifer it directly feeds. Not only that, the river’s water is used for agricultural irrigation, for industry, to support barge traffic along the Missouri and Mississippi Rivers, for recreation, and to support the ecosystems that depend on the river for their survival.
In the previous post, I reported that the snowpack in the western United States has declined by 23%, and it is forecast to decline more by 2038. The eastern border of the study area forms the western boundary of the Missouri River Basin. Will the changing western snowpack impact the Missouri River’s ability to supply Missouri’s needs?
The answer is complicated. Precipitation in the Upper Missouri River Basin has historically fallen mostly as snow, building a winter snowpack that slowly melts during the spring. The snowmelt is gathered into reservoirs created by 6 large dams along the Missouri River, plus more than 40 smaller ones on tributaries. The 6 large dams begin at the Gavin’s Point Dam on the Nebraska-South Dakota border, and extend upriver to the Ft. Peck Dam in Montana. (See Figure 1.) The result is that water flow below the reservoirs is largely controlled by man, not nature.
The annual water yield from the Missouri River is small compared to the size of its basin. The data is given in Figure 2, where the red columns represent the length of the rivers, and the blue line represents their average discharge. No other river in the USA serves such a large basin with so little water. In drought years it is already too small to fully meet all of the demands that are put on it, resulting in conflict over how to manage the river, and over which values to give priority. The conflict has primarily been between up-river interests, which would like to see water allocated to support irrigation, drinking water, and mitigation in their states during periods of drought, and down-river interests, which would like to see water released to support commercial navigation on the river.
In 2004, the Army Corps of Engineers changed the rules by which the river is operated to reduce water releases during drought. During drought years, this better supports up-stream interests, but results in a shorter season during which the river can support barge traffic. The result has been a decrease in annual tonnage moved on the river (Figure 3).
In addition, development in the Upper Missouri Basin has increased water demand in that region. A prime example would be the development of the oil and gas reserves in North Dakota. Well drilling uses large quantities of water. (See Figure 4). Given that the water yield from the Missouri River is already too small to fully support all of the demands placed on it, any increase in demand is bound to constrain supply even further.
The constraints discussed above, however, are all man-made constraints. How will climate change and the declining western snowpack affect all of this?
The snowpack decline has occurred because of increasing temperature, not decreasing precipitation. Figures 5 repeats a chart I published in January 2016, showing that precipitation has increased in the region over time.
Figure 6 shows that the 2011 National Climate Assessment projects that the annual flow on the Missouri River will actually increase by about 15% by 2070. However, more precipitation will fall as rain instead of snow, and the snow that does fall will melt sooner. This means that more water will enter the reservoirs during winter and early spring, and less during late spring and summer. In addition, increased temperature will increase evaporation from the river and reservoirs, and it will increase water consumption by crops, leading to earlier and increased demand for water. There is a potential mismatch between when the water is available and when it is needed.
The question will be whether it will be possible to manage the reservoirs successfully under the new conditions. When looking at the water situation in California (here), we discovered that water authorities expected climate change to create reservoir management problems that would result in an increased water deficit during the summer and autumn. It is possible that the reservoirs along the Missouri will encounter similar problems, but it is not certain.
One potential difference is that California has multiple, relatively short rivers, leading to only one large reservoir per river, and perhaps one or two small feeder reservoirs. The Missouri River, however, is a single long river. It has 6 large reservoirs chained along it, plus at least 40 feeder reservoirs on tributaries. This may give managers flexibility in managing the river that is not possible in California.
Five separate water resource studies have been undertaken to determine how climate change will impact the ability of the Missouri River to meet the demands placed on it. Unfortunately, they have not all been completed, and I can find no comprehensive analysis.
For the time being, problems with water supply on the Missouri River involve human decisions about how to manage the river. To date, in the State of Missouri they have primarily impacted the barge industry, plus the farmers and industries that depend on the barge industry to transport their goods and supplies.
Drew, John, and Karen Rouse. 2006. “Missouri Water in High Demand.” Missouri Resources, Winter, 2006. Downloaded 5/31/2017 from https://dnr.mo.gov/geology/wrc/docs/Water-InHighDemand.pdf?/env/wrc/docs/Water-InHighDemand.pdf.
Bureau of Reclamation. 2016. Basin Report: Missouri River. Downloaded 5/25/2017 from https://www.usbr.gov/climate/secure/docs/2016secure/factsheet/MissouriRiverBasinFactSheet.pdf.
Bureau of Reclamation. 2016. SECURE Water Act Section 9503(c) – Reclamation Climate Change and Water. Prepared for United States Congress. Denver, CO: Bureau of Reclamation, Policy and Administration. Downloaded 5/25/2017 from https://www.usbr.gov/climate/secure.
Hanson Professional Services, Inc. 2011. Missouri River Historic Timeline and Navigation Service Cycle. Missouri River Freight Corridor Assessment and Development Plan. Downloaded 5/31/2017 from https://library.modot.mo.gov/rdt/reports/tryy1018.
Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W. Yohe, Eds., 2014: Climate Change Impacts in the United States: The Third National Climate Assessment. U.S. Global Change Research Program, 841 pp. doi:10.7930/J0Z31WJ2. Available online at http://nca2014.globalchange.gov.
Vanosdall, Tiffany. 2013. Missouri River Water Supply. US Army Corps of Engineers. Downloaded 6/1/2017 from https://denr.sd.gov/coewatersupply22Apr2013.pdf.
Wikipedia. List of U.S. Rivers by Discharge. Data retrieved online 5/31/2017 at https://en.wikipedia.org/wiki/List_of_U.S._rivers_by_discharge.
The snowpack over the western United States has declined about 23% since 1981. It is projected to decline more in the future.
I have written a number of posts about the looming water deficit in California due to a projected decline in the snowpack on the Sierra Nevada mountains. Is something similar projected to occur throughout the entire western United States?
Yes. Studies find that the water content of the snowpack throughout the West has already declined 23%, and it is expected to decline more, perhaps up to 30% by 2038.
This decline is not occurring via a decrease in precipitation. Indeed, to date precipitation across the West has actually increased slightly. The decline is occurring due to increased temperature. Some precipitation that used to fall as snow now falls as rain, and the snow that does fall melts more quickly.
Mote and Sharp studied the snow water equivalent* of the snowpack in April from 1955-2016 at SNOWTEL measuring stations operated by the U.S. Natural Resource Conservation Service. Figure 1 shows a map of the stations, with blue dots representing stations where the snowpack increased and orange dots representing stations where the snowpack declined. The size of the dots represent the magnitude of change.
It is easy to see that the vast majority showed declines in the snowpack, in many cases by as much as 80%. Overall, Mote and Sharp computed that there had been an average 23% decline in the western snowpack since 1955.
Fyfe and his colleagues conducted climate modeling to try to determine whether the decline in the snowpack was due to natural causes or human causes. Figure 2 shows the results in a rather complicated graph. Let’s unpack it. The computer models ran from 1950 to 2010. The dashed black line shows the observed trend in the snow water content. The solid blue line shows the projected snow water content if only natural climate causes are included in the model. It doesn’t fit the observed trend very well. The solid black line shows the projected snow water content if both natural and human climate causes are included in the model. It fits the observed data quite closely. (The pink and green lines show data from analyses using other sets of data and need not concern us here. The gray band and blue dotted lines show statistical confidence levels for the computer simulations, and also need not concern us here.)
The simulation that included both natural and human causes agreed with the observed data, but the one that included only natural causes did not. The authors concluded that natural causes could not explain the loss of snowpack in the West. A combination of human and natural causes could explain it.
Fyfe and his colleagues also conducted a suite of climate models to project snowpack loss into the future. The results are shown in Figure 3. In this graph, the y-axis represents the actual snow water content of the snowpack, not the change. The blue line represents the computer model that projected the least snowpack loss in 2030, and the red line represents the computer model that projected the most loss. It is common practice among climate modelers to run a suite of projections, and when this is done, the average of them is often also presented, and it is often taken as likely to be the most accurate. In Figure 3, the average of the projections is represented by the black line.
It is easy to see that the trend in all of the lines is down. There is considerable variation from point-to-point in the red and blue lines, indicating that the projections expect there to be considerable variability in the snowpack from year-to-year. The black line is pretty smooth, however, as might be expected from an average of several analyses, and it has a consistent downward trend. The losses in snowpack in some of the projections ran as high as 60%, though average loss across the suite of projections was about 30%.
A 30% decline in the snowpack does not sound so dire; after all the projections are for a 60% loss of snowpack in California (see here). However, that projection was for the end of the century. This projection is for 2038; that’s only 20 years from now.
Some may wonder about how little snow water equivalent is shown on the y-axis of Figure 3. In the 1990s, the snowpack maxed-out each year at only 6+ cm. of snow water equivalent. In thinking about this number, remember two things: first, a centimeter of water represents somewhere between 3 and 20 centimeters of snow, with an average value being somewhere around 10 cm. Thus, 6 cm. of snow water equivalent would roughly equal 60 cm. of snow, or 23.6 inches. Thus, the average depth of the snowpack was about 2 feet. Second, remember that the measurements were averaged across hundreds of locations; some were high and received a great deal of snow, but some were relatively low (low altitude means more rain, less snow), or were located in areas that don’t receive much precipitation of any kind.
Much of Missouri depends on the Missouri River as a water supply, including both Kansas City and St. Louis. The Missouri River gets much of its water from the western snowpack. A declining snowpack may, or may not, have implications for our water supply, depending on whether the reservoirs along the Missouri River can accommodate the shift toward earlier snowmelt and increased rain. I will look at this issue in the next post.
* Snow water equivalent: Different types of snow hold different amounts of water. Thus, scientists don’t just measure how deep the snow is. Rather, at a given location they take a representative sample of the snowpack and melt it, thereby determining how much water it holds. This is the snowpack’s snow water equivalent at that given location. April is generally when the snowpack is at its maximum.
Environmental Protection Agency. 2016. Climate Change Indicators in the United States: Snowpack. Retrieved online 5/22/2017 at https://www.epa.gov/sites/production/files/2016-08/documents/print_snowpack-2016.pdf.
Fyfe, John, Chris Kerksen, Lawrence Mudryk, Gregory Flato, Benjamin Santer, Neil Swart, Noah Molotch, Xuebin Zhang, Hui Wan, Vivek Arora, John Scinocca, and Yanjun Jiao. 2017. “Large Near-Term Projected Snowpack Loss Over the Western United States.” Nature Communications, DOI: 10.1038/ncomms14996. Retrieved online 5/14/2017 at https://www.nature.com/articles/ncomms14996.
Gov. Jerry Brown officially declared California’s drought emergency over on Friday, April 7. It was a fitting ending to one of the worst episodes in California’s drought-laden history.
Or was it? The next two posts update California’s water situation. This one focuses on the current short-term situation. The next one focuses on the future, with an eye toward the future impact of climate change. I have personal reasons for following California’s water situation – I have family living there. But in addition, California is the most populous state in the Union, it has the largest economy of any state, and the state grows a ridiculously large fraction of our food. What happens in California affects us here in Missouri.
Is the short-term drought truly over? Yes, I think so. The vast majority of California’s precipitation falls during the winter, and the snowpack that builds up in the Sierra Nevada Mountains serves as California’s largest “reservoir.” As it melts, it not only releases water that represents about 30% of the state’s water supply, but it also feeds water into the underground aquifers that provide groundwater to much of the state. Thus, the size of the snowpack is the most important factor in determining California’s water status. California measures the water content of the snowpack electronically and manually. The measurements around April 1 are considered the most important, as that is when the snowpack is typically at its largest. Figure 1 shows the report for this year. Statewide, the water content of the snowpack was 164% of average for the date, almost 2/3 larger than average. The water content was significantly above average in all three regions of the snowpack, North, Central, and South.
I follow the snow report at Mammoth Mountain Ski Resort to provide a specific example of the snow conditions. Figure 2 shows that through March, Mammoth received over 500 inches of snow, one of the highest totals in the record going back to 1969-70. The column for 2016-17 has very large blue and orange sections, indicating that the majority of the snow fell in January and February. Figure 3 confirms the impression. It charts the amount of snowfall at Mammoth during each month of the 2016-17 snow season, and compares it to the average for that month across all years. You can see that both January and February were monster snow months, especially January. By March, snowfall had already fallen below average. I wouldn’t make too much of this fact, one month doesn’t make a trend.
California also stores water in man-made reservoirs. Figure 4 show the condition of 12 especially important ones on March 31. Most were above their historical average for that date, and many were approaching their maximum capacity. Those who follow this blog know that the Oroville Reservoir actually received so much water that it damaged both the main and emergency spillways, threatening collapse of the dam and requiring evacuation of thousands of people down stream. (See here.)
In addition, Southern California receives the lion’s share of water drawn from the Colorado River, thus the status of Lake Mead, the largest reservoir on the Colorado, is important to the state. A study in 2008 found that there was a 50% chance the reservoir would go dry by 2021. On March 31, Lake Mead was at 1088.26 feet above sea level. (This doesn’t mean there were that many feet of water in the reservoir, Hoover Dam isn’t that tall. Rather, it represents how many feet above sea level the surface of the water was. Lake Mead’s maximum depth is 532 feet.) The current level represents 41.38% of capacity. Figure 5 shows the level of the lake over time. You can see that the line tends to go up with the spring snowmelt, and down during the rest of the year. This year it is up very slightly year-over-year, but the trend has been relentlessly down since 2000.
The conclusion seems inescapable: for this year at least, California has plenty of water. The short-term drought is over. One year doesn’t make a climate trend, however. In the next post I will consider the implications of this wet winter for California’s water situation going into the future.
Barnett, Tim, and David Pierce. 2008. “When Will Lake Mead Go Dry?” Water Resources Research, 44, W03201. Retrieved online at http://www.image.ucar.edu/idag/Papers/PapersIDAGsubtask2.4/Barnett1.pdf.
CA.GOV. Governor Brown Lifts Drought Emergency, Retains Prohibition on Wasteful Practices. Viewed online 4/10/2017 at https://www.gov.ca.gov/home.php.
California Data Exchange Center. Conditions for Major Reservoirs: 31-Mar-2017. Viewed online at http://cdec.water.ca.gov/cdecapp/resapp/getResGraphsMain.action.
California Department of Water Resources. Snow Water Equivalents (inches) for 3/30/2017. Viewed online 3/31/2017 at http://cdec.water.ca.gov/cgi-progs/snowsurvey_sno/DLYSWEQ.
Mammoth Mountain Ski Resort. Snow Conditions and Weather, Extended Snow History. Data downloaded 4/2/2017 from http://www.mammothmountain.com/winter/mountain-information/mountain-information/snow-conditions-and-weather.
Eating fish is thought to have healthful benefits, including cognitive benefits for the young and a reduction in the risk of cardiovascular disease in adults. However, environmental toxins limit the amount of fish you should eat. The principle of bioaccumulation, which explains why, was reviewed in the previous post.
Whether fish are safe to eat depends on the water where they were caught. The Missouri Department of Health and Senior Services publishes a report identifying lakes, rivers, and streams where environmental contamination requires a fish advisory. This post looks at the report for 2017.
Table 1 lists the bodies of water for which fish advisories have been issued, the species of fish affected, the sizes of fish affected, the contaminants, and the limit that should be observed (serving advice).
Looking at the table, the toxins include chlordane, lead, mercury, and PCBs. In some cases the fish are safe to eat once weekly, in other cases only once monthly, and in some cases they should not be eaten at all. Several species from rivers near Missouri’s old lead belt tend not to be safe at all. I’ve posted on the Big River previously (here).
The advisories are separated into those that apply to all consumers, and those that apply to “sensitive populations.” Please look at who is included under “sensitive populations”: children younger than 13 and women who are either pregnant, nursing, or of childbearing age. Wow, that is a huge portion of the population! For them, there is no fish caught in any body of water in the United States that is safe to consume more than once weekly. And for them, several important species of game fish caught in Missouri waters should only be consumed once monthly.
Figure 1 shows a map of the affected bodies of water. Looking at the bodies of water affected, you can see that they cover a lot of territory: the entire lengths of the Mississippi and Missouri Rivers in the state, the major portion of the Big River, the Blue River, Clearwater Lake (ironic, no?), and Montrose Lake.
The contaminants of concern listed by the Missouri report include chlordane, PCBs (polychlorinated biphenyls), lead, and methylmercury. Chlordane was an insecticide. It was widely used as a termite control in residences, and it was used widely on crops. Starting in 1988, sales of chlordane were banned in the United States. However, chlordane persists in the environment. It adheres to soil particles in the ground and very slowly dissolves into groundwater, where it migrates to rivers and lakes. Once in the water of rivers and lakes, it bioaccumulates. That is why, even though banned in 1988, it is still a contaminant of concern in Missouri fish. Elevated levels of chlordane in the blood are associated with an increased risk of cognitive decline, prostate cancer, type-2 diabetes, and obesity. According to the Missouri report, levels of chlordane are gradually decreasing, but remain a concern in some bodies of water.
PCBs are a family of chemicals that were once widely used as insulating and cooling liquids in electrical mechanisms. PCBs were banned in the United States in 1979, however they are extremely long-lived compounds, and it is estimated that 40% of all PCB ever manufactured remain in use. Toxicity varies among specific chemicals in the family. Exposure to PCBs is capable of causing a variety of health effects, including rashes, reduced immune function, poor cognitive development in children, liver damage, and increased risk of cancer. PCBs in the environment generally enter bodies of water, where they enter the bodies of aquatic species and bioaccumulate up the food chain. According to the Missouri report, levels of PCB are gradually decreasing, but remain a concern in some bodies of water.
Lead is a heavy metal that was once heavily mined in Missouri. Lead mining continues, and as recently as 2014, more lead was released into the environment in Missouri than any other toxic chemical. (See here.) Lead used to be released into the environment through the inclusion of tetraethyl lead in gasoline, and through lead paint. Both of those uses have been banned in the United States. Today, lead enters the environment through mine tailings. Thus, it is of greatest concern in locations that either have or had significant lead mining activities (portions of Southeastern Missouri, for instance). Tailings containing lead were (are) dumped on the ground. From the tailings lead washes into nearby bodies of water, where it is ingested by aquatic species and then bioaccumulates. Lead is readily absorbed by living tissue. It affects almost every organ and system in the body. At high levels it can be immediately dangerous to life and health. At lower levels, symptoms include abdominal pain, weakness in fingers, wrists, and ankles, blood pressure increases, miscarriage, delayed puberty, and cognitive impairment.
Mercury enters the environment from many sources. One important source is coal. When coal is burned, it is emitted up the flue. Though the amount in any lump of coal is tiny, so much coal is burned to produce energy that tons and tons are emitted every year. The mercury falls out of the atmosphere, where it gets washed into bodies of water. There, it is converted by microbes into methylmercury, which is then ingested into aquatic species, and it bioaccumulates. In children a high level of methylmercury has been associated with language and memory deficits, reduced IQ, and learning disabilities. In adults, it has been associated with an increased risk of cardiovascular disease and autoimmune conditions.
It seems to me that for all of these contaminants, the situation may be slowly improving, though it is still problematic. The persistence of these contaminants in the environment, in many cases decades after their manufacture was banned, demonstrates an important environmental principle: the environmental problems you create may not go away quickly. They are likely to remain with you for a long, long time.
Missouri Department of Health and Senior Services. 2017. 2017 Missouri Fish Advisory: A Guide to Eating Missouri Fish. Downloaded 3/9/17 from http://www.health.mo.gov/fishadvisory.
Wikipedia. Chlordane. Viewed online 3/15/2017 at https://en.wikipedia.org/wiki/Chlordane.
Wikipedia. Lead. Viewed online 3/15/2017 at https://en.wikipedia.org/wiki/Lead.
Wikipedia. Methylmercury. Viewed online 3/15/2017 at https://en.wikipedia.org/wiki/Methylmercury.
Wikipedia. Polychlorinated biphenyl. Viewed online 3/15/2017 at https://en.wikipedia.org/wiki/Polychlorinated_biphenyl.
Eating fish may be good for you, or it may poison you. (Pick one)
In the 1970s, researchers reported that native people living in Greenland (Inuits) had very low rates of heart disease compared with counterparts living in Denmark. Scientists attributed these health benefits to the consumption of fish and sea mammals containing high levels of long-chain polyunsaturated fatty acids. Recently, however, research has questioned the accuracy of these early studies, as more recent research shows that the rate of heart disease and heart attack among the Inuit are similar to those in non-Inuit populations. Thus, there has been some question regarding how strong the association is between reduced risk of cardiovascular disease and fish consumption. The situation reminds me of one of my favorite sayings: It ain’t what we don’t know that’s gonna hurt us, it’s what we do know that just ain’t so.
Over the years, thousands of research studies have been conducted, with the result that the consumption of fish is included in most dietary guidelines. The benefits are primarily considered to be the previously mentioned reduction in the risk of coronary heart disease in adults, but also an improvement in cognitive development in infants and young children.
The current dietary guidelines in the USA have moved away from the concept of the minimum daily requirement. Instead they describe recommended patterns of healthy eating. The recommendation for seafood has not changed, however: 8 oz. of seafood per week. (Dietary Guidelines, p. 18)
It is generally recognized, however, that some fish species contain significant levels of contaminants. These contaminants include a number of really nasty poisons, including chlordane, polychlorinated biphenyls (PCBs), lead, and methylmercury. These compounds can be toxic even in very small amounts, and they are bioaccumlative.
Bioaccumulation is an important concept in understanding environmental toxins. The basic idea is that even tiny amounts of toxin can build up in the body. Here’s how: at any given feeding, a toxin may be eaten in such tiny amounts that there is no immediate effect on the animal that consumes it. However, it is absorbed by the body, and it is not readily eliminated by natural processes. Thus, over time, the amount in the body builds up each time the animal eats a little more.
Imagine a lake. Mercury emitted by coal-burning power plants falls into the lake, where microbes convert it to methylmercury. Algae living in the lake take in some of that methylmercury. Along comes a tiny fish fry, and it eats some of that algae. Now with each mouthful of algae, the fish fry ingests a dose of methylmercury. And it starts to build up. How many mouthfuls of algae does a fish fry eat? I don’t know, but it is quite a lot. Now, along comes a medium-sized fish, and it eats the fish fry. With one bite, it has ingested not just a tiny amount of methylmercury, but all the methylmercury that built up in the body of the fish fry during its lifetime. How many fish fry does a medium-sized fish eat? I don’t know, but it is quite a few, and the medium-sized fish ingests all of the methylmercury built up in the bodies of each fish it eats. Now, along comes a large fish, and it eats the medium-sized fish. With one bite, it has ingested not just a tiny amount of mercury, but all the methylmercury built up in the body of the medium-sized fish. How many medium-sized fish does a large fish eat? I don’t know, but it is quite a few, and the large fish ingests all of the methylmercury built up in the bodies of each fish it eats.
Now, let’s imagine that our fish are living in a Missouri lake. Along comes a fisherman, and he catches one fish per week and eats it. That will be 52 fish per year. Now, I don’t know what the actual numbers are, but let us assume that a fish fry eats 1,000 individual alga, while a medium-sized fish eats 100 fry, and a large fish eats 100 medium-sized fish. These estimates may be wildly wrong, but the point is to illustrate the principle of bioaccumulation, and they will allow us to do so.
Using the estimates above, each fish fry will ingest the methlymercury contained in 1,000 algae; each medium-sized fish will ingest the amount contained in 100,000 algae; each large fish will ingest the amount contained in 10 million algae, and in a year, our fisherman will ingest the amount contained in 520 million algae. If he continues for 10 years, he will consume the amount contained in 5.2 billion algae.
Over time, the amount of methylmercury in our fisherman’s body will build up, perhaps eventually reaching the point where it starts to poison him.
Now, my presentation is over-simplified; in real life bioaccumulation is much more complex. Further, the numbers I chose for my progression were totally arbitrary. Nonetheless, they illustrate the basic idea of bioaccumulation. And the principle applies not only to methylmercury, but also to lead, PCBs, and dioxins.
The result is that, however good for you eating fish may be in theory, there are limits due to environmental contaminants. The next post will look at what those limits are in Missouri.
Committee on a Framework for Assessing the Health, Environmental, and Social Effects of the Food System; Food and Nutrition Board; Board on Agriculture and Natural Resources; Institute of Medicine; National Research Council; Nesheim MC, Oria M, Yih PT, editors. A Framework for Assessing Effects of the Food System. Washington (DC): National Academies Press (US); 2015 Jun 17. ANNEX 1, DIETARY RECOMMENDATIONS FOR FISH CONSUMPTION. Available from: https://www.ncbi.nlm.nih.gov/books/NBK305180.
Missouri Department of Health and Senior Services. 2017. 2017 Missouri Fish Advisory: A Guide to Eating Missouri Fish. Downloaded 3/9/17 from www.health.mo.gov/fishadvisory.
U.S. Department of Health and Human Services and U.S. Department of Agriculture.
2015–2020 Dietary Guidelines for Americans. 8th Edition. December 2015. Available at http://health.gov/dietaryguidelines/2015/guidelines.
Missouri’s water consumption declined in 2010. The decline was smaller than the decline for the nation as a whole, and it may be due to economic factors rather than conservation.
Missouri is not one of the regions of the country where water supplies are most tightly constrained. Thus, Missouri is not under as much pressure to reduce consumption as some states are, California for instance. Nevertheless, water consumption is an important environmental variable, and it is useful to know what the trends are in Missouri.
The data for this post comes from the U.S. Geological Survey’s Water Use Data for the Nation data portal. The portal’s data for Missouri extends back to 1985.
Figure 1 shows Missouri’s water consumption by end use, including thermoelectric power, for 1985-2010. Missing data makes comparisons across years difficult: data for thermoelectric power is missing for 1985, and data for livestock is missing for 1985, 1990, and 1995. With those caveats, Missouri’s water consumption appears to have increased through 2005, and then declined slightly in 2010. This contrasts with national consumption, which peaked in 1980.
The decline in 2010 may represent the beginning of a trend, but before assuming that it does, recall that 2010 was during the depths of the Great Recession, and the decline in water consumption may be related to a decline in economic activity, not conservation efforts.
Thermoelectric power is by far the largest consumer of water in Missouri. Missouri’s largest power plants (Labadie, Iatan, Thomas Hill, Rush Island, New Madrid, Sioux, Hawthorne, Meramec, and Callaway) are all located on rivers or reservoirs, and they withdraw water for cooling and for making steam. Thermoelectric water withdrawals peaked in 2005 at 6,181 million gallons per day, and declined in 2010 to 5,915 million gallons per day, a decline of 4%.
Irrigation was the second largest consumer of water in Missouri. The peak year for irrigation consumption was 2000 at 1,431 million gallons per day, and it was about 2% lower in 2010 at 1,402 million gallons per day.
Figure 2 shows Missouri’s water consumption by end use with thermoelectric power excluded. I think that thermoelectric power is not a proper end use for two reasons. First, most water withdrawn for thermoelectric power is used for cooling, and it is returned to the environment. When returned, it may cause local problems because it is hot, but generally it is not contaminated. Second, electricity is not generated for its own use, it is sold to customers for their end uses. Thus, it may be useful to understand Missouri’s water consumption with thermoelectric power excluded.
Once thermoelectric power is excluded, irrigation and public supply become by far the largest consumers of water in Missouri. Irrigation was discussed above. Public supply represents all water that is delivered to customers by a public water utility. Here, things get a little complex. Some domestic and industrial water consumers supply their own water themselves. These consumers represent a small fraction of the total, and are shown on the chart in red and green. Most domestic and commercial consumers, and some industrial consumers, are supplied water by public water utilities, and these are the consumers represented by the dark blue public supply category on the chart. Both irrigation and public supply peaked in 2000, and by 2010 had declined 2% and 4% respectively. Because the trend is consistent from 2000 to 2005 to 2010, I am less inclined to suspect it is a function of the Great Recession.
Stacked column charts are great for showing categorized data over time, but pie charts show more dramatically the percentages belonging to each category in a given year. Figure 3 shows Missouri water consumption in 2010 by end use, thermoelectric power included. It shows that thermoelectric power accounted for 70% of all Missouri water withdrawals. Irrigation accounted for 17% and public supply for 10%. Together, the three accounted for 97% of Missouri water withdrawals.
Figure 4 shows the same data with thermoelectric power excluded. If one considers thermoelectric power withdrawals a non-consumptive use, then irrigation and public supply together accounted for 91% of the water consumed in Missouri in 2010.
Because of the drought in California, I have also been following water supplies out there. I will post on California’s water situation after the start of the new year.
Maupin, M.A., Kenny, J.F., Hutson, S.S., Lovelace, J.K., Barber, N.L., and Linsey, K.S., 2014, Estimated use of water in the United States in 2010: U.S. Geological Survey Circular 1405, 56 p., http://dx.doi.org/10.3133/cir1405.
U.S. Geological Survey. 2014. Water Use Data for the Nation. USGS National Water Information System. Search criteria: Years 1965,1970,1975,1980,1985,1990,1995,2000,2005,2010; Area UNITED STATES; Catogory ALL. Data accessed 12/3/2016 at http://waterdata.usgs.gov/nwis/wu.
Water consumption in the United States declined 18% between 1980 and 2010.
Water consumption is an issue of concern in areas where water supplies are constrained. Constructing a comprehensive study of how much water is consumed in the United States is a gargantuan task, but the United States Geological Survey does it every five years. It takes several years to put together, and the report Estimated Use of Water in the United States in 2010 came out in 2014. Historical data are also available on the USGS National Water Data Information System data portal.
Figure 1 shows that water consumption in the USA grew rapidly from 1965 to 1980, but since then has declined. The peak in 1980 was 430 billion gallons consumed per day and by 2010 it had declined 18% to 355. The decline occurred despite the fact that during the period Gross Domestic Product grew by 229% and population grew by 36%.
Figure 2 shows similar data, except it is separated into end uses. The shape of the trend matches the one in Figure 1. It is impossible, however, to separate water consumption by end use without either missing some that you should count, or double counting some that you shouldn’t. The result is that, for any given year, if you total the amount used by each end use in Figure 2, it won’t precisely match the amount shown in Figure 1. The disagreement is small, never as much as 5%, and often much smaller than that. It would probably matter if you were doing research, but for our purposes here, it probably doesn’t.
Figure 2 shows that more water is withdrawn for thermoelectric power (nuclear and coal-burning power plants, primarily) than for any other use. Second is irrigation. Both have decreased since 1980. I don’t know the precise reasons why, but if I had to guess, I would say that retiring nuclear and coal-burning power plants in favor of natural gas and renewable energy, improved irrigation practices, and switching to soil cover/crops that require less water were all part of the story.
Public Supply did not peak in 1980, it increased right through to 2005. That makes sense, given that population and GDP have increased. Public supply includes all water delivered by a public water utility.
I don’t consider water withdrawn for thermoelectric power to be a true end use. For one reason, it is returned to the environment and used again without much treatment. For another, electricity is not generated for its own use, it is provided to customers for their end uses. Thus, it might be useful to look at water consumption with thermoelectric power excluded. Figure 3 shows the data. Now it becomes clear just how much of our water consumption really goes to irrigation: 60-67% in any given year. And suddenly, public supply looks more significant, accounting for up to 24% of consumption. Industry has made impressive progress in reducing water consumption.
Figure 4 shows water consumption by the source of the water: fresh or saline, surface water or groundwater. By far the largest amount is sourced from fresh surface water, and the second largest amount is sourced from fresh groundwater. If dry regions of the country turn to desalination to augment their water supply, look for the saline fraction to grow.
One final chart: these stacked column charts are good for showing categorized data over time, but they don’t show the categories for any given year as powerfully as does a pie chart. So Figure 5 is a pie chart showing water consumption in the USA by end use, thermoelectric power included, for 2010. It very powerfully shows that almost half of all water withdrawn in the USA that year went into nuclear and coal-burning power plants. About 1/3 of it went for irrigation.
In the next post I’ll look at water consumption in Missouri. I’m going to take a week off for the holiday, however, so it will appear in January.
Bureau of Economic Analysis. Current Dollar and Real GDP. National Economic Accounts. Downloaded 12/4/2016 from http://www.bea.gov/national/index.htm#gdp.
Maupin, M.A., Kenny, J.F., Hutson, S.S., Lovelace, J.K., Barber, N.L., and Linsey, K.S., 2014, Estimated use of water in the United States in 2010: U.S. Geological Survey Circular 1405, 56 p., http://dx.doi.org/10.3133/cir1405.
U.S. Census Bureau. Part II. Population of the United States and Each State: 1790-1990. Downloaded from http://www.census.gov/population/www/censusdata/Population_PartII.xls.
U.S. Census Bureau. 2011. Table 1. Intercensal Estimates of the Resident Population for the United States, Regions, States, and Puerto Rico: April 1, 2000 to July 1, 2010 (ST-EST00INT-01. Downloaded from http://www.census.gov/popest/data/intercensal/national/nat2010.html.
U.S. Geological Survey. 2014. Water Use Data for the Nation. USGS National Water Information System. Search criteria: Years 1965,1970,1975,1980,1985,1990,1995,2000,2005,2010; Area UNITED STATES; Catogory ALL. Data accessed 12/3/2016 at http://waterdata.usgs.gov/nwis/wu.
In 2014 and 2015 toxic algal blooms on Lake Erie caused the City of Toledo to warn residents not to drink the city’s public water. This algal bloom has become a more-or-less annual event.
In 2015, a plume of algae spread along the Ohio River, covering 636 miles, about 2/3 of the entire river, from Wheeling WV, to Cannelton IN. For more than a month it curbed boating, caused problems for water utilities, and drove swimmers out of the water.
This year (so far, at least) the headlines were grabbed by a toxic algal bloom in Florida. The green slime originated in Lake Okeechobee, then spread via rivers to the Fort Meyers area on the west, and especially to the Stewart area on the east. States of emergency were declared in Martin, Lee, St. Lucie, and Palm Beach Counties.
These are all examples of Harmful Algal Blooms, or HABs. What’s going on, and how has Missouri been affected?
(Click on graphics for larger view.)
Algal blooms are caused by microorganisms. They occur naturally in all water, and are only absent if you purify and treat the water. Even in purified water, as every swimming pool or aquarium owner knows, they will multiply and slime your water if you don’t give the water constant vigilance.
The most common of the microorganisms is often called blue-green algae. Despite its common name, it is not algae at all, but a phylum of bacteria, called cyanobacteria. Most species of it are harmless, but some species are toxic. Sometimes conditions conspire to cause these bacteria to multiply explosively, causing what we call an algal bloom. These blooms sometimes contain significant numbers of toxic microorganisms, which make drinking the water, or even swimming in it, hazardous. The most common of these is a genus called microcystis. For some reason HABs are increasing in frequency.
In most cases, casual contact with the water causes mild reactions like rashes. Drinking it, however, can cause liver damage, and can even be fatal. They are harmful to wildlife as well as humans, and can cause large fish kills.
Many of the HABs occur along our nation’s seacoasts. Missouri is an inland state, however, so for the rest of this post I will concern myself only with algal blooms on freshwater systems. HABs are a relatively recent subject of study, so nobody knows how often they have occurred and where. Similarly, in a state like Missouri, many of them occur in relatively small bodies of water that may not be monitored. Thus, the blooms may go undetected.
HABs causing significant large-scale disruption have not yet been reported in Missouri, but as Figure 2 shows, they have been reported in many of our neighboring states. There is no reason to believe that Missouri is immune.
In 2007, the United States Geological Survey completed a study looking for the presence of toxic species of cyanobacteria and for the toxins they produce in the nation’s lakes and reservoirs. They found that:
- Cyanobacteria are ubiquitous, occurring in 98% of the samples they collected;
- One or more toxic species of cyanobacteria were present in 67-95% of the waters samples collected;
- Toxins were present in only 4.0-7.7% of samples, depending on the toxin. Thus, the presence of algae, and even of toxic species of algae, does not necessarily mean that the water is unsafe. Only when a bloom causes the number of toxic cyanobacteria to increase does the situation become problematic.
Figures 3, 4, and 5 show the sites tested, and the locations of sites where the cyanobacteria toxins were found. Figure 3 shows Cylindrospermopsin, Figure 4 shows Saxitoxin, and Figure 5 shows Microcystin. The color codes for the concentration: clear means none detected, blue means detected at low concentrations, yellow means detected at moderate concentrations, and red means detected at high concentrations. Microcystin and Cylindrospermopsin were detected in Missouri, the latter at a high concentration.
(Click on graphics for larger view.)
Some of this should not be surprising. I suspect that any of us who have spent time near bodies of water in Missouri have seen algae on them. Indeed, Figure 6 shows an algal bloom occurring on a lagoon in Forest Park in St. Louis on the day I wrote this article (7/21/16). The light green material in the water is the algae.
Missouri tests lakes for the concentration of chlorophyll-a, but not streams. Chlorophyll-a is a green pigment associated with organisms that do photosynthesis. It is present in cyanobacteria, and the assumption is that chlorophyll-a levels indicate the amount of cyanobacteria in the water. In 2014, excess levels of chlorophyll-a impaired more acres of Missouri lakes than any other cause. Lakes in all regions of Missouri are showing increasing trends in chlorophyll-a levels, with trends in the Glaciated Plains and Osage Plains regions being statistically significant.
While a useful water quality standard, the reported concentration of chlorophyll-a only represents the level at the time testing occurred. It cannot be translated into the presence or absence of an algal bloom at other times during the year. Further, the USGS assessment found that chlorophyll-a is not a reliable indicator of the presence of algal toxins. Neither algal counts nor algal toxins are tested in Missouri’s surface water or in Missouri’s drinking water. The Department of Conservation encourages the reporting of fish kills in the state, but there is no system for reporting or tabulating algal blooms.
Phosphorus appears to be the factor that most limits algal growth in Missouri’s lakes. Where algae has access to phosphorus, it grows more vigorously. Phosphorus is a pollutant that flows into Missouri’s lakes from some industrial or urban sources, but it is especially an agricultural chemical that runs off from fertilized farms.
Much of Missouri’s population draws its drinking water from the Missouri and Mississippi Rivers. Iowa, Illinois, Kansas, Minnesota, Nebraska, and Wisconsin are among the nation’s most intensively farmed states, and Missouri is downstream from all of them. Could our two rivers experience HABs as did Lake Erie and the Ohio River? Could HABs make our water undrinkable? For how long?
Is there a reason to think that Missouri should be immune from such problems? I don’t know of one. So far we have dodged the bullet. When or how a seriously disruptive HAB might occur in Missouri is anybody’s guess.
Dewey, Eliza. “Where Will the Green Slime Go? Florida Tracks Spreading Algae.” The Miami Herald. 7/7/2016. Viewed online 7/21/16 at http://www.miamiherald.com/news/local/environment/article88302462.html.
Lakes of Missouri Volunteer Program. Blue Green Algae in Missouri. Downloaded 7/21/16 from http://lmvp.org/bluegreen.
Lopez, C.B., Jewett, E.B., Dortch, Q., Walton, B.T., Hudnell, H.K. 2008. Scientific Assessment of Freshwater Harmful Algal Blooms. Interagency Working Group on Harmful Algal Blooms, Hypoxia, and Human Health of the Joint Subcommittee on Ocean Science and Technology. Washington, DC. https://www.whitehouse.gov/sites/default/files/microsites/ostp/frshh2o0708.pdf.
Missouri Department of Natural Resources. 2015. Missouri Integrated Water Quality Report and Section 303(d) List, 2014. Downloaded 4/20/2016 from http://dnr.mo.gov/env/wpp/waterquality/303d/303d.htm.
Neuhaus, Les. “Miles of Algae and a Multitude of Hazards.” The New York Times. 7/18/2016. Viewed online 7/21/16 at http://www.nytimes.com/2016/07/19/science/algae-blooms-beaches.html.
United States Geological Survey. 2016a. New Science Challenges Old Assumptions about Harmful Algal Blooms. Viewed online at https://www.usgs.gov/news/new-science-challenges-old-assumptions-about-harmful-algal-blooms.
United States Geological Survery. 2016b. New Study on Cyanotoxins in Lakes and Reservoirs Provides Insights into Assessing Health Risks. Viewed online 7/22/2016 at http://toxics.usgs.gov/highlights/2016-05-31-cyanotoxins_in_lakes.html.
Wines, Michael. “Toxic Algae Outbrteak Overwhelms a Polluted Ohio River.” The New York Times. 9/30/2015. Viewed online 7/22/16 at http://www.nytimes.com/2015/10/01/us/toxic-algae-outbreak-overwhelms-a-polluted-ohio-river.html.
Zwerneman, Annie. 2014. Monitoring Harmful Algal Blooms? There’s an App for That! The EPA Blog, 7/17/14. Downloaded 7/22/16 from https://blog.epa.gov/blog/tag/usgs.