U.S. ENVIRONMENTAL PROTECTION AGENCY NATIONAL EUTROPHICATION SURVEY WORKING PAPER SERIES REPORT ON LAKE BEMIDJI KLTRAMI COUNTY MINNESOTA REGION V WORKING PAPER No, PACIFIC NORTHWEST ENVIRONMENTAL RESEARCH LABORATORY An Associate Laboratory of the NATIONAL ENVIRONMENTAL RESEARCH CENTER - CORVALLIS, OREGON and NATIONAL ENVIRONMENTAL RESEARCH CENTER - LAS VEGAS, NEVADA •fcOPO 697.O32 ------- REPORT ON LAKE BEMIDJI BELTRAMI CQUM1Y MINNESOTA EPA REGION V WORKING PAPER No, 84 WITH THE COOPERATION OF THE MINNESOTA POLLUTION CONTROL AGENCY AND THE MINNESOTA NATIONAL GUARD NOVEMBER, 1974 ------- 1 CONTENTS Page Foreword ii List of Minnesota Study Lakes iv, v Lake and Drainage Area Maps vi, vii Sections I. Conclusions 1 II. Lake and Drainage Basin Characteristics 3 III. Lake Uater Quality Summary 4 IV. Nutrient Loadings 9 V. Literature Reviewed 13 VI. Appendices 14 ------- 11 FOREWORD The National Eutrophication Survey was initiated in 1972 In response to an Administration commitment to investigate the nation- wide threat of accelerated eutrophication to fresh water lakes and reservoi rs. OBJECTIVES The Survey was designed to develop, in conjunction with state environmental agencies, information on nutrient sources, concentrations, and impact on selected freshwater lakes as a basis for formulating comprehensive and coordinated national, regional, and state management practices relating to point-source discharge reduction and non-point source pollution abatement in lake watersheds. ANALYTIC APPROACH The mathematical and statistical procedures selected for the Survey’s eutrophication analysis are based on related concepts that: a. A generalized representation or model relating sources, concentrations, and impacts can be constructed. b. By applying measurements of relevant parameters associated with lake degradation, the generalized model can be transformed into an operational representation of a lake, its drainage basin, and related nutrients. c. With such a transformation, an assessment of the potential for eutrophication control can be made. LAKE ANALYSIS In this report, the first stage of evaluation of lake and water- shed data collected from the study lake and its drainage basin is documented. The report is formatted to provide state environmental agencies with specific information for basin planning [ 3O3(e)], water quality criteria/standards review [ 3O3(c)], clean lakes [ 3l4(a,b)], and water quality monitoring [ 1O6 and §305(b)] activities mandated by the Federal Water Pollution Control Act Amendments of 1972. ------- 111 Beyond the single lake analysis, broader based correlations between nutrient concentrations (and loading) and trophic condi- tion are being made to advance the rationale and data base for refinement of nutrient water quality criteria for the Nation’s fresh water lakes 0 Likewise, multivariate evaluations for the relationships between land use, nutrient export, and trophic condition, by lake class or use, are being developed to assist in the formulation of planning guidelines and policies by EPA and to augment plans implementation by the states. ACKNOWLEDGMENT ThL if of the National Eutrophication Suivey (Office of Research & Development, U. S. Environmental Protection Agency) expresses sincere appreciation to the tlinnesota Pollution Control Agency for professional involvement and to the Minnesota National Guard for conducting the tributary sampling phase of the Survey. Grant J. Merritt, Director of the Minnesota Pollution Control Agency, John F. McGuire, Chief, and Joel G. Schilling, Biologist, of the Section of Surface and Groundwater, Division of Water Quality, provided invaluable lake documentation and counsel during the course of the Survey; and the staff of the Section of Municipal Works, Divi- sion of Water Quality, were most helpful in identifying point sources and soliciting municipal participation in the Survey. Major General Chester J. Moeglein, the Adjutant General of Minnesota, and Project Officer Major Adrian Beltrand, who directed the volunteer efforts of the Minnesota National Guardsmen, are also gratefully acknowledged for their assistance to the Survey. ------- iv NATIONAL EUTROPHICATION SURVEY STUDY LAKES STATE OF MINNESOTA LAKE NAME COUNTY Albert Lea Freeborn Andrusia Beltran’ii Badger Polk Bartlett Koochiching Bear Freeborn Bemidji Beltrami Big Stearns Big Stone Big Stone, MN; Roberts, Grant, SD Birch Cass Bi ackduck Bel trami Blackhoof Crow Wing Budd Martin Buffalo Wright Calhoun Hennepin Carlos Douglas Carrigan Wright Cass Beltrami, Cass Clearwater Wright, Stearns Cokato Wright Cranberry Crow Wing Darling Douglas Elbow St. Louis Embarass St. Louis Fall Lake Forest Washington Green Kandiyohi Gull Cass Heron Jackson Leech Cass Le Homme Dieu Douglas Lily Blue Earth Little Grant Lost St. Louis ------- V LAKE NAME COUNTY Madison Blue Earth Malmedal Pope Mashkenode St. Louis McQuade St. Louis Minnetonka Hennepin Minnewaska Pope Mud Itasca Nest Kandiyohi Pelican St. Louis Pepin Goodhue, Wabasha, MN; Pierce, Pepin, WI Rabbit Crow Wing Sakatah Le Sueur Shagawa St. Louis Silver McLeod Six Mile St. Louis Spring Washington, Dakota St. Croix Washington, MN; St. Croix, Pierce, WI St. Louis Bay St. Louis, MN; Douglas, WI Superior Bay St. Louis, MN; Douglas, WI Swan Itasca Trace Todd Trout Itasca Wagonga Kandlyohi Wallmark Chisago White Bear Washington Winona Douglas Wolf Beltrami, Hubbard Woodcock Kandiyohi Zumbro Olmstead, Wabasha ------- 940 30’ 470 30’ Lav nia 27A. WOL LAK a BEMIDJI, WOLF, ANDRUSIA & CASS LAKES Tributary Sampling Site Lake Sampling Site Sewage Treatment Facility Map Location ------- 940 55 0 94 45’ nap Location ilavinia 47° 30’ LAKE BEMIDJI Tributary Sampling Site Lake Samplinq Site Sewage Treatment Facility ------- LAKE BEMIDJI STORET NO. 27C1 I. CONCLUSIONS A. Trophic Condition: Survey data show that Lake Bemidji is eutrophic. Of the 60 Minnesota lakes sampled in the fall when essentially all were well-mixed, 28 had less mean total phosphorus, 36 had less mean dissolved phosphorus, but only 5 had less mean inorganic nitrogen. Of the 80 lakes studied, 24% had less mean chlorophyll a, and 19% had greater Secchi disc transparency. Marked depression of dissolved oxygen with depth was noted at station 1 in July and September and at station 2 in July, 1972. Reportedly, a portion of Lake Bemidji was chemically treated for algae control in 1971 (Bonnema and Johnson, 1972). B. Rate-Limiting Nutrient: The results of the algal assay show that the lake was nitro- gen limited at the time the assay sample was collected. Lake data indicate nitrogen limitation at the other sampling times as well. C. Nutrient Controllability: There are no known point sources impacting Lake Bemidji within the limits of the Survey. The N/P ratio of 28/1 in the mean annual nutrient loads of the inlet (see page 12) ------- 2 suggests that point sources in the drainage are not large nutrient contributors (of course, Lake Irving provides some phosphorus entrappment, but it is unlikely that It is enough to account for the N/P ratio observed). During the sampling year, Lake Bemidji received a total phosphorus load at a rate less than that proposed by Vollenweider (in press) as “dangerous” (i.e., a eutrophic rate) but more than a “permissible” or oligotrophic rate (see page 12). ------- 3 II. LAKE AND DRAINAGE BASIN CHARACTERISTICS A. Lake Morphometryt: 1. Surface area: 6,420 acres. 2. Mean depth: 32 feet. 3. Maximum depth: 76 feet. 4. Volume: 205,440 acre/feet. 5. Mean hydraulic retention time: 268 days. B. Tributary and Outlet: (See Appendix A for flow data) 1. Tributaries - Name Drainage area* Mean flow* Lake Irving outlet 2 (Mississippi River) 584.0 mi 366.3 cfs Minor tributaries & 2 immediate drainage - 35.5 ml 19.5 cfs Totals 619.5 mi 2 385.8 cfs 2. Outlet - Mississippi River 630.0 mi 2 ** 385.8 cfs** C. Precipitation***: 1. Year of sampling: 22.2 inches. 2. Mean annual: 21.1 inches. t DNR lake survey map (1967); mean depth by random-dot method. * Drainage areas are accurate within ±5%; mean daily flows are accurate within ±10%; and ungaged flows ar accurate within ±10 to 25% for drainage areas greater than 10 mi ’. ** Includes area of lake; outlet flow adjusted to equal sum of inflows. See Working Paper No. 1, “Survey Methods”. Rc9ea h Cc Xe ? 35th Street 0 Corvail1 , Q oqQfl ------- 4 III. LAKE WATER QUALITY SUMMARY Lake Bemidji, one of a chain of upper Mississippi River lakes (see map, page vi), was sampled three times during the open-water season of 1972 by means of a pontoon-equipped Huey helicopter. Each time, samples for physical and chemical parameters were collected from two stations on the lake and from a number of depths at each station (see map, page vii). During each visit, a single depth—integrated (15 feet to surface) sample was composited from the two stations for phytoplankton identification and enumeration; and during the last visit, a single five-gallon depth-integrated sample was composited for algal assays. Also each time, a depth-integrated sample was collected from each of the stations for chlorophyll a analysis. The maximum depths sampled were 48 feet at station 1 and 46 feet at station 2. The results obtained are presented in full in Appendix B, and the data for the fall sampling period, when the lake was essentially well—mixed, are sumarized below. Note, however, the Secchi disc summary is based on all values. For differences in the various parameters at the other sampling times, refer to Appendix B. ------- 5 A. Physical and chemical characteristics: FALL VALUES (10/21/ 72) Parameter Minimum Mean Median Maximum Temperature (Cent.) 6.1 6.8 6.8 7.4 Dissolved oxygen (mg/i) 10.0 10.7 10.8 11.1 Conductivity (pmhos) 290 295 295 300 pH (units) 8.4 8.4 8.4 8.4 Alkalinity (mg/i) 154 157 156 161 Total P (mg/i) 0.037 0.052 0.050 0.067 Dissolved P (mg/i) 0.028 0.040 0.038 0.055 NO + NO (mg/i) 0.020 0.028 0.030 0.040 Am onia mg/1) 0.030 0.046 0.050 0.060 ALL VALUES Secchi disc (inches) 69 85 86 100 ------- 6 B. Biological characteristics: 1. Phytoplankton — Sampling Dominant Number Date Genera per ml 07/11/72 1. MicrocystiS 2,803 2. Anabaena 940 3. Dinobryon 723 4. Melosira 163 5. Fragilaria 90 Other genera 543 Total 5,262 09/08/72 1. Microcystis 2,355 2. Lyngbya 2,283 3. Anabaena 1,377 4. Dinobryon 399 5. Flagellates 217 Other genera 1 ,231 Total 7,862 10/21/72 1. Melosira 1,747 2. P nabaena 723 3. Fragilaria 602 4. StephanodiscuS 422 5. ChroococcuS 346 Other genera 1 ,52l Total 5,361 ------- 7 2. Chlorophyll a - (Because of instrumentation problems during the 1972 sampling, the following values may be in error by plus or minus 20 percent.) Sampling Station Chlorophyll a Date Number ( pg/i ) 07/11/72 01 9.2 02 8.3 09/08/72 01 02 10/21/72 01 02 C. Limiting Nutrient Study: 1. Autoclaved, filtered, and nutrient spiked — Ortho P Inorganic N ___________ Conc. (mg/i) Conc. (mg/i ) _____________ 0.020 0.047 0.026 0.047 0.032 0.047 0.044 0.047 0.080 0.047 0.080 10.047 0.020 10.047 2. Discussion — The controi yield of the assay alga, Selenastrum capri— cornutum , indicates that the potential primary productivity of Lake Bemidji was moderate at the time the sample was collected. Also, the lack of significant change in yield with increasing increments of orthophosphorus, until nitro- gen was also added, shows that the lake was nitrogen limited. Note the increase in yield when only nitrogen was added. Spike (mg/i ) Control 0.006 P 0.012 P 0.024 P 0.060 P 0.060 P + 10.0 N 10.0 N 6.6 6.9 8.9 17.0 Maximum yield ( mg/i-dry wt. ) 1.3 1.3 1.2 1.0 1.4 37.1 7.8 ------- 8 The lake data indicate nitrogen limitation at the other sampling times as well (N/P ratios were 9/1 or less). ------- 9 IV. NUTRIENT LOADINGS (See Appendix C for all data) For the determination of nutrient loadings, the Minnesota National Guard collected monthly near-surface grab samples from each of the tribu- tary sites indicated on the map (page vii), except for the high runoff months of April and May when extra samples were collected. Sampling was begun in October, 1972, and was completed in September, 1973. Through an interagency agreement, stream flow estimates for the year of sampling and a “normalized” or average year were provided by the Minnesota District Office of the U.S. Geological Survey for the tributary sites nearest the lake. In this report, nutrient loads for sampled tributaries were determined by using a modification of a U.S. Geological Survey computer program for calculating stream loadings*. Nutrient loadings for unsampled “minor tributaries and immediate drainage” (“ZZ” of U.S.G.S.) were estimated by using the means of the nutrient loads, in lbs/mi 2 /year, in streams tribu- tary to nearby Leech Lake at stations 2746C-i , D-1 , F-l, G-l , H—i , and J-l and multiplying the means by the ZZ area in mi 2 . A. Waste Sources: 1. Known municipal - None 2. Known industrial - None * See Working Paper No. 1. ------- 10 B. Annual Total Phosphorus Loading - Average Year: 1. Inputs — lbs P1 % of Source yr total a. Tributaries (non-point load) - Lake Irving outlet (Mississippi River) 23,120 91.4 b. Minor tributaries & immediate drainage (non-point load) - 990 3.9 c. Known municipal - None - - d. Septic tanks* - 190 0.8 e. Known industrial - None - f. Direct precipitation** - 1,000 3.9 Total 25,300 100.0 2. Outputs - Lake outlet - Mississippi River 16,290 3. Net annual P accumulation - 9,010 pounds * Estimated 777 persons residing on lake shore (Holt, et al., 1971); see Working Paper No. 1. ** See Working Paper No. 1. ------- 11 C. Annual Total Nitrogen Loading - Average Year: 1. Inputs - lbsN/ %of Source yr total a. Tributaries (non-point load) - Lake Irving outlet (Mississippi River) 653,760 85.2 b. Minor tributaries & immediate drainage (non—point load) -— 44,410 5.8 c. Known municipal - None - d. Septic tanks* - 7,300 1.0 e. Known Industrial - None - f. Direct precipitation** - 61,850 8.0 Total 767,320 100.0 2. Outputs - Lake outlet — Mississippi River 575,490 3. Net annual N accumulation - 191,830 pounds * Estimated 777 persons residing on lake shore (Holt, et al., 1971); see Working Paper No. 1. ** See Working Paper No. 1. ------- 12 D. Mean Annual Non-point Nutrient Export by Subdrainage Area: Tributary lbs P/mi 2 /yr lbs N/mi 2 /yr N/P Ratio Lake Irving outlet (Mississippi River) 40 1,120 28/1 E. Yearly Loading Rates: In the following table, the existing phosphorus loading rates are compared to those proposed by Vollenweider (in press). Essentially, his dangerous” rate is the rate at which the receiving waters would become eutrophic or remain eutrophic; his “permissible” rate is that which would result in the receiving water remaining oligotrophic or becoming oligo— trophic if morphometry permitted. A mesotrophic rate would be considered one between “dangerous” and “permissible”. Total Phosphorus Total Nitrogen Units Total Accumulated Total Accumulated lbs/acr /yr 3.9 1.4 119.5 29.9 grams/rn /yr 0.44 0.16 13.4 3.3 Vollenweider loading rates for phosphorus (g/m 2 /yr) based on mean depth and mean hydraulic retention time of Lake Bemidji: ‘Dangerous” (eutrophic rate) 0.70 “Permissible” (oligotrophic rate) 0.35 ------- 13 V. LITERATURE REVIEWED Anonymous, 1948. Lake survey report, Lake Bemidji, Beltrami County. MN Dept. Nat. Resources, Minneapolis. Bonnema, Kenneth, and William G. Johnson, 1972. Control of aquatic vegetation, algae, leeches, and swimmer’s itch. MN Dept. Nat. Resources, Minneapolis. Holt, Charles S., Roger A. Schulz, and Curtis M. Hadland; 1971. Patterns of lakeshore usage around Lake Bemidji. Jour. Minn. Acad. Sd., V. 37, Nos. 2 and 3. Hoekstra, Donald J., 1968. Nitrogen and phosphorus analysis of six Mississippi headwater lakes. MS, Limnology Inst., Bemidji State College, Bemidji. Schilling, Joel, 1974. Personal communication (lake map). MPCA, Minneapolis. Vollenweider, Richard A., (in press). Input-output models. Schweiz. A. Hydrol. ------- VII. APPENDICES APPENDIX A TRIBUTARY FLOW DATA ------- TPIA1JTAPY FLOW INFORMATION FOM MINNESOTA 10/30/74 LAKE CODE 7CI HEMIOJI LAKE TOTAL OPAINAGE APEA O LAKE K30.00 51JR-DPAINAGE NOPMALIZED FLOW5 TPIPUTAPY APEA JAN FF9 MAP APP MAY JUN JUL AUG 504.00 290.00 163.00 ?98.00 757.00 763.00 524.00 334.00 263.00 422.00 176.00 138.00 272.00 366.30 630.00 ?7M.01 362.09 ?9?.89 835.25 816.25 560.03 356.43 280.00 446.83 185.70 147.94 276.00 385.86 45.50 8.37 5.04 12.40 49.80 49.40 40.60 19.20 8.95 15.60 9.47 6.46 8.82 39.53 TOTAL D A1NAGE APEA OF LAKE = SUM OF SUP—1)PAINAGE AREAS = SUMMARY 10 7? 160.00 II 7 ’ 131.00 12 72 409.00 I 71 308.00 2 73 114.00 1 73 814.00 4 73 236.00 S 73 230.00 K 73 191.00 7 73 145.00 B 73 2 OA.00 0 73 300.00 10 7’ 172.00 I I 72 140.00 12 72 ‘18.00 I 73 303.00 7 73 174.00 1 72 819.00 4 73 ?0S.00 5 73 203.00 4 73 190.00 7 71 180.00 9 73 200.00 9 73 500.00 10 7? 8.67 I l 7 6.10 1? 7? 13.30 I 73 9.21 7 73 5.39 1 13 13.90 4 73 18.90 5 73 18.40 6 73 IS.30 7 73 11.40 9 7 16.20 9 73 175.00 14 211.00 5 131.00 10 397.00 20 268.00 38 174.00 17 2440.00 1 250.00 19 209.00 N 129.00 I I 206.00 16 350.00 14 227.00 5 140.00 10 405.00 20 264.00 19 174.00 17 2460.00 1 217.00 19 195.00 8 160.00 II 200.00 lb 580.00 14 11.00 5 6.30 10 13.00 20 8.00 18 5.40 Il 302.00 20.00 39 17.00 8 30.30 11 16.00 lb 203.00 27C 343 PlC IA? 27(117 MEAN MONTHLY FLOWS AND DAILY FLOWS TPIHtJIAPY MONTH SEP OCT NOV DEC MEAN YEAR MEAN FLOW DAY 630.00 TOTAL FLOW IN 629.50 TOTAL FLOW OUT = 4622.39 FLOW DAY ?7C1A 1 ?7C1 A? PlC Ill FLOW DAY FLOW 14 217.00 1 389.00 34 17.00 ------- APPENDIX B PHYSICAL and CHEMICAL DATA ------- STOPET RETRIEVAL DATE 74/10/30 27C101 47 28 40.0 094 51 42.0 LAKE BEMIDJI 27 MINNESOTA 11EPALES 2111202 3 0045 FEET DEPTH 00010 00300 00077 00094 00400 00410 00630 00610 00665 00666 DATE TIME DEPTH WATER DO TRANSP CNDUCTVY PH T ALK NO2 NO3 NH3—N PHOS—TOT PHOS—DIS FROM OF TEMP SECCHI FIELD CACO3 N—TOTAL TOTAL TO DAY FEET CENT MG/L INCHES MICROHHO St.) MG/L MG/C MG/L MG/L P MGIL p 72/07/11 10 00 0000 87 360 8.30 171 0.040 0.060 0.024 0.00$ 10 00 0004 20.9 9.4 350 8.30 174 0.040 0.060 0.019 0.10$ 10 00 0015 20.0 8.2 350 8.20 175 0.040 0.050 0.020 0.01$ - 10 00 0040 11.1 0.2 300 7.40 183 0.040 0.370 0.093 0.067 7?/09/08 11 25 0000 84 310 8.10 156 0.040 0.060 0.032 0.1 16 11 25 0004 17.5 7.6 305 8.05 156 0.020 0.040 0.02 ? 0. 512 11 25 0015 17.3 6.1 305 8.00 157 0.030 0.070 0.028 9.017 11 25 0022 17.2 7.3 290 8.00 158 0.050 0.130 0.028 1. 116 II 25 0030 17.2 6.9 310 7.95 157 0.040 0.130 0.S36 l.I$1 11 25 0039 16.4 5.0 310 7.80 158 0.030 0.24$ 0.051 •.S31 11 25 0048 12.7 0.3 355 7.25 182 0.090 0.130 Qr 4 72/10/21 15 20 0000 72 300 8.40 155 0.040 0.060 I. 15 20 0004 6.8 11.1 295 8.40 157 0.020 0.041 0.000 5.. 15 20 0015 6.5 10.8 290 8.40 157 0.020 0.040 0.003 I. 15 20 0022 6.5 10.8 290 8.40 161 0.030 0.050 0.037 1.111 15 20 0030 6.5 10.8 300 8.40 160 0.030 0.050 0.046 S.S 15 20 0041 6.4 10.6 300 8.40 160 0.030 0.060 0.155 SIN 32217 DATE TIME DEPTH CHLPPHYL FROM OF A TO DAY FEET IJG/L 72/07/lI 10 00 0000 9.2J 72/09/08 11 25 0000 6.6J 77/10/21 15 20 0000 8.RJ J* VALUE KNOWN TO BE IN ERROR ------- STi’ -T rr_ii I . .T 1 ./I 27(107 1 00.0 094 51 10.0 LAKE MIi)JI 27 M IN 1WSOTa 1 IE’ALES 2111202 0019 FEET DEPTH 1 • 7/ 00410 OO ,30 • r, c . -‘ I AL ( NO2. N03 J .-43—N P1-sOS—TOT ‘ -‘ - (--‘I r It- 1 ) CACO t J—T0TAL TOTAL 1 . ./ I . 4I) r-i1 MC,/L M(.,/L MG/L lG/L P P46/L r)ATE A.- rL) ’ I I) I)A1 F’- I 77/ 7/II 1 ) “) 1-s ) ‘ -)r Ifl l(i 5.’) I - It. - -sr , 72/-IO II ‘• 1 “fl”.S I I ‘ • - fl .’—. IT 1 II • 1) ) 72/11/21 14 “t .:n I-. ,• 14 • ‘ Ii I L. ‘I .’! 1L. f.’) —, I—. 1 ( ‘ ) ‘I IT • ‘1-4 1 ) ,A 72/ 17/ I V I! 72/ I )/2, - ) ‘ 4.4’ 174 ‘I . ’ . 15’ .4u 171 0.040 0.050 0.014 0.008 2’ • • 14 . .c 172 0.030 0.050 0.015 0.006 II • I • 1 si3 7.4() . 0 176 149 0.07( 5 0.020 0.140 0.080 0.030 0.025 0.021 0.011 I’. . 7.’ Ifl3 .? 1 1L 9 0.0?0 0.070 0.025 0.011 I7. — .-‘ 100 2.15 15 ’ ) 0.030 0.080 0.021 0.010 7• 7. ’- 0C s ’.15 149 0.010 0.080 0.021 0.010 7.. 7. - ’ I ‘1fl’ 1 u. - .15 ‘.-.e 149 155 0.020 0.020 0.070 0.030 0.020 0.067 0.009 0.055 P. * I . 0’ ‘ •4 5) 154 0.020 0.030 0.041 0.028 7.- I • “-)C ’ .4 ( 154 0.030 0.040 0.063 0.054 ) 1.- 15P 0.030 0.040 0.066 0.051 7. 1 .7 i.43 155 0.030 0.050 0.054 0.042 7. 1’ • 7 -,.40 156 0.040 0.060 0.048 1’ . 41( c ’.40 1:,5 0.030 0.050 0.040 0.028 ‘I ‘ I J* V LlJ- r0)4rI 1) — 7 j ) - . ------- APPENDIX C TRIBUTARY DATA ------- ST’)P T PETPTFVAL I)#T Th/l(’/J O ?7CLA1 LS27CIA1 47 28 00.0 094 52 30.0 MISSISSIPPI IVEk 27 7.5 BEMIDJI WEST 1/LAPSE r3FP4IDJI MiRI)C, .5 M I UPSTREAM 1 1EPALES DATE F POP’ TO T I F OF DAY (‘GE 30 N93-N TOTAL 00671 P’-iOS-DIS OR I HO MG/L P 4 00665 PHOS—TOT MG/L ‘ LAKE IRVING 2111204 0000 FEET 0ci’ 3J DEPTH O’ MO3 N— TOT AL FEET MG/L 0 .070 0.0?5 ‘j. O lS C ‘. 115 O • 170 C .os • 0 1 1 0 • 0 I ‘3 PS 0.010K 0.0 lOPS ).O 10K 0 • 0 7 7?/I0/ 14 72/11/05 10 10 7?/12/l0 10 05 71/01/20 09 10 73/OP/IP I? 00 71/01/17 0 0 71/04/01 11 30 73/04/i’ 09 00 7l/05/I 09 40 73/06/03 09 15 71/07/OR 08 35 73/OR/il 08 15 71/0 /1 ’ 09 10 DEPTH oo c TOT KJEL N MG/I 0.610 0 .4R0 O • 540 0 • 480 0 • O • L Ř 0.580 7.600 0 .540 O • c)q 1.051) 1 • 760 0.044 0.005K 0.030 0.026 0.016 (1.024 0.019 0.005K 0.012 0.130 0.009 0.015 0.154 0.011 0.025 0.115 0.009 0.030 0.028 0.008 0.040 9.03u 0.006 0.032 O. 005 P S 0.010 0.035 0.010 0.006 0.030 0.011 0.011 0.055 0.02S 0.015 0.070 0.056 0.018 0.045 K VALUE KNOWN TO BE LESS THAN INDICATED ------- ST’)kFT ETPJ VAL ?TC1NI LS27C IN1 47 29 30.0 09” 50 00.0 MISSISSIPPI P1VE ?7 7.5 BEMIDJI EAST 0/LAKE BEMIDJI HET N BEMIDJI SIP AND PP TRESTLE 1IEPALES 2111204 4 0000 FEET DEPTH 006?5 00610 00671 00665 flATE TIME DEPTH N07 N03 TOT KJEL ‘JH3—N P iOS—D1S PHOS—TOT FP )M OF J—T’JTAl_ N TUTAI O THO TO DAY F FT M(,/L ‘ /L .iC,/L MG/L P MG/L P 72/12/101020 3.0 ’ 0.720 0.032 0.009 0.019 73/0I/?0 00 45 0.01.) 0.6 9 O.u3? 0.005K 0.005K 7 /07/1 1? 10 ( .019 0.560 0.030 0.005 1 < 0.010 71/03/17 01 5’ 0.07’ 1.1 70 0.05R 0.00 51< 0.020 71/04/01 11 45 3. Oi Oc 0.540 0.009 0.005K 0.030 71/04/14 09 05 0.016 0.5 O 0.00 51< 0.0051< 0.020 71/05/19 09 0 0.010K 0.500 0.0051< 0.005K 0.030 71/06/01 0915 0.010K 7.103 iJ.026 0 .005K 0.025 71/07/0 0965 0.0131< 0.6 1(J 0.01 ? 0.009 0.020 7 3/OR/ Il O 20 0.025 0.620 0.031 0.0051< 0.025 71/09/1 09 40 0.013 0.’60 3.025 0.017 0.045 K VALUE KNOWN TO BE LESS THAN INDICATED ------- |