What is the overall quality of Missouri’s surface water? Is it improving over time? The following series of posts will attempt to answer those questions.
Missouri is home to a lot of surface water. By volume, the surface water is dominated by a few very large rivers (the Mississippi and the Missouri) and by a few large man-made reservoirs (Truman Lake, Lake of the Ozarks, Bull Shoals Lake, and Table Rock Lake are the 4 largest). By far the most stream miles and lake surface acres, however, come from small creeks, streams, lakes, and ponds. In 2014, 24,491 miles of streams and 303,014 acres of lake surface were large enough to qualify for protection under the federal Clean Water Act, and these are known as “classified” waters. Smaller streams, lakes, and ponds qualify for a lower degree of protection under state clean water laws, and they account for an estimated 234,395 stream miles and 605,979 acres of lake surface. They are known as “unclassified” waters. Thus, Missouri’s unclassified streams account for more than 9 times as many stream miles as do classified streams, and Missouri’s unclassified lakes account for about 2 times as many acres as do classified lakes. Table 1 summarizes Missouri’s surface waters by type.
Classified streams and lakes are the largest bodies of water in the state, and they receive priority in Missouri’s efforts to protect water quality. They are governed by the federal Clean Water Act. Every 2 years, to comply with this act, the Missouri Department of Natural Resources assesses and reports the water quality in these classified water bodies. The most recent report is for the year 2014.
People use surface water for all kinds of purposes. Table 2 shows the number of stream miles and lake acres classified for each use (more than one use may apply to a body of water).
Often, water is used for one or more of these uses, but not all of them. Water that is of sufficient quality to be used for all of its intended purposes is said to be in full support of assessed uses. Water that is not of sufficient quality for one or more of its intended uses is said to be impaired.
The following post will review trends in the overall quality of Missouri’s surface waters from 2002-2014: the number of stream miles and lake acres that are supported for all intended uses, vs. those that are impaired. After that, I will look at the problems that impair some Missouri waters, and I will finish by providing a map of Missouri’s impaired waters.
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.
(A word about the availability of the Missouri Water Quality Reports. As of 5/1/2016, reports for 2002, 2004, 2006, 2008, 2010, 2012, and 2014 are available on the Department of Natural Resources, Water Protection Website. Though the 2014 report is dated April 24, 2014, it was not available on the website until much later. The report for 2016 is not yet available, and may not be for many months.)