628.168 0m2n OMERNIK NUTRIENT CONCENTRATIONS IN STREAMS FROM NONPOINT SOURCES Nutrient Concentrations in Streams From Nonpoint Sources JUN 14 1977 LIBRARY CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY U.S. Environmental Protection Agency Corvallis, Oregon 97330 April 1977 3 Maps Nutrient Concentrations in Streams from Nonpoint Sources by James M. Omernik* Introduc tion The enclosed maps (3) and graphs (2) were compiled to provide a national overview of nutrient concentrations in streams from nonpoint sources. These materials are being incorporated into an Ecological Research Series (U.S. Environmental Protection Agency, Office of Research and Development) report to be issued this summer. Meanwhile, we hope they will be useful to water resource planners and managers for making general assessments of stream nutrient levels attributable to nonpoint sources. The enclosed materials are based on (1) the mean annual nutrient concen¬ trations from a nationwide set of 928 National Eutrophication Survey (NES) stream sites associated with watersheds impacted only by nonpoint sources and (2) the relationships of the NES nonpoint data to general land use categories and other macro-watershed characteristies. Although there is considerable disagreement about what exactly comprises a "point source" as compared to a "nonpoint source", very generally speak¬ ing, point sources are considered to be municipal and industrial waste discharges and nonpoint sources are everything else. Exceptions, which are roughly defined in section 502 of Public Law 92-500 (U.S. Congress, 1972), include concentrated animal feeding operations and also other operations which are or may be discharging pollutants through a pipe, ditch, channel, etc. For the purpose of this study, nonpoint source watersheds are those without municipal and industrial waste discharges and animal feedlots identified as point sources. It should be clearly understood that the values illustrated on the maps are those of mean annual concentrations representative of existin g non¬ point source areal characteristics, which include both natural and anthro¬ pogenic sources. The NES stream samples were taken on the average of once a month for one year (see map insert for years of sampling initiation and distribution of sites). Land use and other drainage area characteristics data were compiled from available aerial photography and other materials dated as closely to the sampling years as possible. Sampling and laboratory methods were uniform throughout the entire data set. For more detailed information on the sampling and laboratory methods, the history, objectives and overall design of the NES, and the land use study appendage to the NES, * Corvallis Environmental Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Corvallis, OR 97330 jNIVERS"' - ilUNOIS UBKArt' VI URBANA-CHAMP* * * ■ lo 1 / t «m/v*wi see the following publications: NES Working Paper No. 175 (U.S. Environ¬ mental Protection Agency, 1975), and The Influence of Land Use on Stream Nutrient Levels (Omernik, 1976). Map Develop ment Basically, the development of each of the three stream nutrient concentra¬ tion maps involved several preliminary processes. First, the actual mean annual nutrient concentrations were assigned to the representative posi¬ tions of their true sampling site locations on a 1:3,168,000 scale base map. Then, an enlargement of Anderson's Major Land Uses map (U.S. Geologi¬ cal Survey, 1970) was prepared in color at the 1:3,168,000 scale. It should be noted that the land use category scheme used on Anderson's map is compatible, with some transposition, with that used for the enclosed graphs. Next, a blank drafting film overlay was attached to the base map on which the actual concentrations for a given nutrient form had been annotated. These in turn were superimposed on, and registered to, the enlarged land use map. Then a 1:3,168,000 map illustrating all of the study watersheds by color coded dots, indicating their respective land use categories, was compared to the above map to enable the compiler to determine whether or not data points were representative of typical general land use in their respective regions. By studying these mapped data and knowing the general relationships shown by the graphs, one could visualize the general land use patterns and the spatial relationships between observed stream nutrient concen¬ trations and land use. Additional help in understanding the part other macro-watershed characteristies play was provided by comparison with various other maps including: distribution maps of fertilizer expendi¬ tures, cattle and other agricultural products or activities, (U.S. Dept, of Commerce, Bureau of Census, 1973); isometric maps of acid precipita¬ tion observations (Likens, 1975); and an "ecoregions" map, which in itself provides a regional breakdown of a synthesis of the macro-water¬ shed characteristies relative to forest and rangeland resources (Bailey, 1976). Therefore, the actual drawing of the stream nutrient concentra¬ tion map units was guided to a great extent by the alignment of Anderson's land use map units. However, as the observed values and their apparent relationships and interrelationships with existing land use and other phenomenon varied regionally, the map units were drawn to reflect these variations. The nutrient concentration map units (each representing a range of concen¬ trations) were determined mainly by analysis of the frequency distributions of the 928 values for each nutrient form. The objective was to obtain a fairly even distribution of values (observations) throughout each map's range of map units. Understandably, the map unit sizes were adjusted slightly to allow for even, easy-to-understand intervals. , . The categories shown in the reliability map inset reflect several factors. The two most important are (1) the distribution of data points and (2) the types and homogeneity of land use in a given region together with the probable applicability of land use-stream nutrient concentrations rela¬ tionships to that region. Also important were the significance of surface runoff in determining stream nutrient concentrations and the distinguish- ability of nonpoint from point source impact on streams. Examples of where the latter becomes a problem can be found in the flat tidal reaches of the Atlantic Coastal Plain and throughout much of Florida. Obviously regions where NES stream sampling sites were concentrated and where land use and watersheds were well defined, the reliability would be categorized as good. On the other hand, arid areas where stream data (where streams exist) are difficult to obtain and/or where surface runoff is an insigni¬ ficant factor, the reliability would be categorized as poor. Areas cate¬ gorized fair were generally those where NES tributary sampling data were scarce or lacking, but where land use and other macro-drainage area charac¬ teristics were such that reasonable estimates could be made based on the relationships and interrelationships observed in similar areas. V Bib!iography Bailey, R. G. 1976. Ecoregions of the United States. Map, scale - 1:7,500,000. U.S. Forest Service, Ogden, Utah. Likens, G. E. 1975. Acid Precipitation: Our Understanding of the Phenomenon. In: Acid Precipitation. Proceedings of a Conference on Emerging Environmental Problems. EPA-902/9-75-001, U.S. Environ¬ mental Protection Agency, Region II, New York, New York. pp. 45-75. Omernik, J. M. 1976. The Influence of Land Use on Stream Nutrient Levels. EPA Ecological Research Series, EPA-600/3-76-014. U.S. Environmental Protection Agency, Corvallis Environmental Research Laboratory, Corvallis, Oregon. 105 pp. U.S. Congress. 1972. An Act to Amend the Federal Water Pollution Control Act. Public Law 92-500, 92nd Congress, Washington, D.C. U.S. Department of Commerce, Bureau of Census. 1973. 1969 Census of Agriculture; Graphic Summary Vol. V, Part 15. U.S. Government Print¬ ing Office, Washington, D.C. 145 pp. U.S. Environmental Protection Agency. 1975. National Eutrophication Survey Methods, 1973-1976. National Eutrophication Survey Working Paper No. 175. U.S. Environmental Protection Agency, National Eutro¬ phication Research Program, Corvallis, Oregon. 91 pp. U.S. Geological Survey. 1970. The National Atlas of the United States. U.S. Government Printing Office, Washington, D.C. 417 pp. . . .009 Land Use mft vs. o CN >. >■ ♦- on to tf> a) 0) 0 o w k_ _c c 3 3 U CD "D a> .. E • • E ___ (U > Q) O "S § - O) c 0 ang pred u k. O) o _a k_ u k. 05 X O' ad l. a> < < &? a. 6? a. £ fc? D fc? m c O c O o l/> m O o 3 SJ o o m K 3 m 3 m e o in m £ k_ m IN Al Al -q a> v> t/> u •” o a a> = o LL. O LL. —*u o ^ a. fc? a m o m c o c N. m K 3 m3 Al Al Al Al rv m m o iv & * C C 0 o c c •i 0)-Q a> O) •• E O o oi - ?, “O c ® c c 2 0) O a o O Q* X ad _ Od £* Jr 0) • —• • Q) k_ fc? D 0 5 VI m O 6 3 w» m e a> rv in e k. 0) Al « o Al a> Al <£ O' 0 CO CM N. O o 0) k- 3 ~3 u an ■iculture iculture k. O) _n k_ O) L. O) < 3 < < fc? o O in O m O" rv O' Al Al Al Al 144 - 72 74 Milligrams per Liter RELIABILITY Good TOTAL INORGANIC NITROGEN CONCENTRATIONS* (milhgroms/liter) 0 050 TOTAL INORGANIC NITROGEN CONCENTRATIONS IN STREAMS FROM NONPOINT SOURCES NOTE «I James M Omernik Total the National Eutro- itrogen doto phication Survey (NES) conducted li 1972 through 197 5 Stream Corvallis Environmental Research Laboratory U S. Environmental Protection Agency pled at least month!' one adapted li US Geolog 1977 DISTRIBUTION OF N E S NONPOINT SOURCE WATERSHEDS land Uses the United States by Fi J Marschner 1950) by Jomes SCALE 1:7,500,000 R Anderson 1967 The Noti Each of the 928 dots represents a stream sampling site and its associated drainage area 72/73 and 74 refer to the year streom sampling began in each group of states Atlas of the United Stotes 1970 doto fi ites assoooted with watershed 1000 tins >mt sources and the relationships ot the 'egories ond other macro-watershed choi Department of Geography Cartogrophrc Service Oregon Stole University RELIABILITY Good TOTAL NITROGEN CONCENTRATIONS milligrams/liter) TOTAL NITROGEN CONCENTRATIONS IN STREAMS FROM NONPOINT SOURCES 0.901 NOTE tt I James M Omernilc Totol from the Notionol Eutrophicatioi (NES) ducted ) from 1972 through 1975 pled ot leost monthly for rvallis Environmental Research Laboratory U S Environmental Protection Agency Mop unit alignments ore adopted from U S Geological Su,ve '' M °llQ"d Uses |o revision of Mb| 0 , Lond Uses m United States by Francis J Morschner 1950) by Jam R Anderson 1967 The National Atlas of the United State Washington DC, US Government Printing Office 1970 1977 DISTRIBUTION OF N E S NONPOINT SOURCE WATERSHEDS SCALE 1:7,500,000 Each of the 928 dots represents a stream sampling site and its associated drainage area 72.'73, and 74 refer to the year stream sampling began in each group of states mop based on data from 928 sites associated with watersheds 1000 km. contain point sources and the relationships of mean annua 9 en e i use categoric macro wolershcd characteristic Department of Geography Cartographic Service. Oregon Slate University RELIABILITY TOTAL PHOSPHORUS CONCENTRATIONS (m til ig r ams/ lite r) TOTAL PHOSPHORUS CONCENTRATIONS IN STREAMS FROM NONPOINT SOURCES 0 021 to 0 030 NOTE James M Omernik d a ro 197? through 197 5 Six'om orvallis Environmental Research Laboratory U S Environmental Protection Agency 1977 0 071 to 0 100 DISTRIBUTION OF N E S NONPOINT SOURCE WATERSHEDS Mo|or land U 1950) by J o m e ■ SCALE 1:7,500,000 Each of the 928 dots represents a stream sampling site and its associated drainage area 7 2 73 and 74 refer to the year stream Sampling began in each group of states R Anderson 1967 The N Wash mg t< 1970 I 7 500 000 data fi 928 sampling ties associated 1000km epresentalive of mean annua containing only nonpo d alo oteished chai Department of Geography Cortogrophic Set Oregon State Uni ; vr S 6 il*] McMrk. «-t * VT.Ilto-wi U» Angalo. M. • Utah Monb ftsami. B iiuk C \ v