Journal of the Academy of Science

Volume 38 Number 2 Article 13

1972

Pollution From Sewage Loading in River and Lakes Downstream from Bemidji

James Ludwig Bemidji State College

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Recommended Citation Ludwig, J. (1972). Pollution From Sewage Loading in River and Lakes Downstream from Bemidji. Journal of the Minnesota Academy of Science, Vol. 38 No.2, 101-104. Retrieved from https://digitalcommons.morris.umn.edu/jmas/vol38/iss2/13

This Article is brought to you for free and open access by the Journals at University of Minnesota Morris Digital Well. It has been accepted for inclusion in Journal of the Minnesota Academy of Science by an authorized editor of University of Minnesota Morris Digital Well. For more information, please contact [email protected]. Pollution from sewage loading in nver and lakes downstream from Bemidji

JAMES LUDWIG*

ABSTRACT - The deleterious effects and downstream distribution of pollutants from domestic sewage discharged at Bemidji., Minnesota, are examined with reference lo parameters for pollu­ tion as defined by the state's Pollution Control Agency (PCA). Periodic overloading of the resort city's sewage treatment plant also is considered, along with problems pertinent to a community upstream of popular vacation facilities on a lake and river system.

The deleterious influence of domestic sewage on lakes waters (which include ) cited the addition of and streams is well documented ( Schindler, 1971.), but the effluent from the city of Bemidji as the central cause only recently has public knowledge of the problems been of rapidly accelerated eutrophication and deterioration of reflected in meaningful corrective legislative and agency Wolf and Andrusia Lakes, and Allen's Bay of Cass Lake. action. Minnesota, a state with an abundance of fresh In spite of violations of Minnesota state law and statutes, water resources, has been noticeably slow to act to pre­ the state sought no binding legal action to force cleanup serve the quality of surface waters (Anderson, 1971). through 1971. Bemidji is a typical example of the medium-sized Min­ Late in 1971 the author initiated a lawsuit under the nesota community with inadequate sewage treatment fa­ Minnesota Environmental Rights Act of 1971 (chapter cilities and continuous effluent discharge to surface wa­ 952, Minnesota Statutes) to force compliance with exist­ ters. Annually, more than 400 million gallons of par­ ing state effluent standards identified in regulations 15, tially treated sewage are discharged to the Mississippi 25, 28 of Minnesota water pollution standards. Because River (Figure 1). This effluent comes from a treatment no water quality investigations were in progress on this plant that includes settling tanks for primary removal of system in late 1971 , the author set out to collect data for solids and a trickling filter for secondary clarification. court action on the unenforced standards. Special empha­ Maximum flow capacity for treatment at the design level sis was placed on effluent data relating to the established of 50 mg.I. of biological oxygen demand in the effluent is effluent standards for phosphorus ( one milligram per 1.3 million gallons per day (mgd). Average flows in liter) and turbidity ( 25 Jackson turbidity units). Data 1971 were 1.1 mgd, with the maximum flow recorded at on stream discharge and loading factors also were col­ 1. 78 mgd. Overloading of the sewage plant occurs at ir­ lected through part of this study to determine the distri­ regular intervals throughout the year. The present fa­ bution of soluble phosphate in downstream lakes. cility was constructed in 1955-56 under pressure from area residents and the Minnesota Department of Health Sample bottles cleaned to cease discharge of primary treated effluent directly to Samples of effluent and stream waters were obtained . The 1956 facilities included a force main in one-gallon plastic bottles. Before use, the bottles and around the east side of Lake Bemidji to deliver the caps were washed in distilled water and 2N warm HCl treated effluent to the rather than to the and rinsed to eliminate any phosphate adsorption. The Lake itself. containers were numbered prior to field work. Because a Within a decade of the installation of this system, se­ limited number of bottles were available, some were re­ rious eutrophication effects were observed in downstream used at the same sampling sites (Figure 1.). After each lakes. Severe aquatic vascular plant infestations, excep­ use the bottles and caps were rinsed in distilled water and tionally long and noxious alga1 blooms, and a generally occasionally in 2N HCl. For collecting the samples, serious decline in recreational value of downstream wa­ bottles were immersed about six inches below the surface ters appeared. Wild Rice (Zinzania aquatica) disap­ and filled and rinsed with river water three times before peared from the Mississippi River-lake system from be­ a sample was kept. All samples stored longer than four low the point of Bemidji's effluent discharge to Cass hours were treated with 10 ml. chloroform preservative. Lake. Effluent samples were obtained by inserting a rubber hose into the discharge pipe at the river and drawing material Water quality monitoring with a 12V electric bilge pump. The pump was allowed In 1966 the Minnesota Water Resources Commission to run from three to five minutes before a samp1e was (later absorbed into the Minnesota Pollution Control taken to ensure accuracy of the sample. Samples were Agency) began monitoring water quality of this river stored at 4°C. or analyzed the same day as collected. system (MPCA Report #427). This study, together with Turbidity analysis on the effluent was performed with work by John Osborne on a model DR-EL portable field engineer's laboratory kit ,. DR. JAMES P. LUDWIG, now an independent con­ (Hach Chemical Co.). Soluble phosphate measurements sulting ecologist at Bemidji, was director of the Center were made initially with the same engineer's laboratory for Environmental Studies at Bemidji State College and conducted the study reported here while serving in that kit which uses Hach's stannaver modification of the am­ position. monium molybdate-stannous chloride reduction technique Journal of, Volume Thirty-eight, Nos. 2 and 3, 1973 101 l. Lake. Bemidji Outle1: 2. Bemidji Municip•l Effluent ). Pove.rdam 4. Wolf · L,ike Inlet 5. Vo lf Lake Out let 6. Lak ~ Andni•i"• Outlet a. 7. Tu rt. le River Out let 8. Pike Bay Inle.t. 9. Hiuiuippi River

for soluble phosphate of Standard Methods. A more sen­ 1971. Twenty-three samples of sewage effluent obtained sitive method utilizing ascorbic acid as the reductant of between between 17 October and 31 December averaged the phosphomolybdate complex was used (newly adopted 34.1 mg./ 1. soluble phosphate. Table 1 gives all of the by the Federal Environmental Protection Agency) on all data collected for this system as analyzed by the Hach analyses made after 28 December, 1971. The procedure method. During December 1971 the soluble phosphate included extraction steps with isobutanol to increase sen­ level in the river was observed to increase approximately sitivity and decrease interferences. The ascorbic acid re­ eight-fold between the Lake Bemidji outflow and the duction method was run against known standards each powerdam stations seven miles downstream. After pass­ time a batch of samples was analyzed in order to obtain age through nineteen miles of river and two lakes at Lake greatest accuracy. It was found that the Hach Stannaver Andmsia outlet, these receiving waters were found to method and colorimeter consistently overestimated sol­ have almost a four-fold higher level of soluble phosphate uble phosphate in these waters by 0.01 to 0.03 mg. / 1. than Lake Bemidji's water. averaging 0.018 mg./ 1. at ranges between 0.01 and 0.30 Between December 28, 1971, and January 29, 1972, mg./1. Accordingly, in reporting the data obtained in the study was expanded to include Cass Lake and con­ these ranges by the Hach Stannaver method, 0.0 I 8 tributing rivers besides the Mississippi in order to deter­ mg. / 1. has been deducted from each reading. At ranges mine whether increased soluble phosphate levels were from 3 to 6 mg./ 1. the Hach method consistently over­ detectable after passage through Cass Lake and to gen­ estimated real soluble phosphate levels by about eight erate a soluble phosphate budget for the chain of lakes. percent (range 6-13 percent variation); similarly, 8 Table 2 gives these data, aH of which were obtained with percent was deducted from the values in this range. the ascorbic acid reductant technique. These data showed Chemical analyses were performed by Prof. A. Joseph a considerably larger increase in soluble phosphate than Hopwood of St. Cloud (Minn.) State College, Michael the data taken in December. A 10.6 fold rise in soluble Sellon, a senior at Bemidji State College, and the author. phosphate was noted between Lake Bemidji's outlet and Current data for stream discharge estimates were ob­ the powerdam station. The river system does not appear tained using a Gurley Junior current meter. Measure­ to recover a normal soluble phosphate level in winter un­ ments were made of stream velocity at the 0.6 depth. til after passage through Cass Lake. Stream cross-sectional area was estimated by measuring Stream discharge was measured at three points on the width and averaging depth at four locations across the Mississippi River above Cass Lake, the other flowing in­ stream. Stream discharge was estimated in cubic feet per lets to Cass Lake and the Mississippi River one-half mile second by multiplying the average stream velocity at 0.6 below the Knutson Dam (Cass Lake outlet) on January stream depth by the cross-sectional area as recommended 16. Table 3 lists these data together with a calculated by Corbett (1962.). soluble phosphate budget based only on flowing waters for each of the three lakes in this chain. Although there Soluble phosphate increases noted is surely some input from homes surrounding each of Soluble phosphate level of the Mississippi River above these lakes, this source has been ignored in these budgets. the effluent discharge averaged 0.0208 mg. / 1. for six­ For example, Holt et al . ( 1971) estimated that the total teen samples taken from December 5 to December 3 11 , phosphate which could be added to Lake Bemidji by 102 The Minnesota Academy of Science TABLE 1. Soluble Phosphate levels in the Mississippi River at TABLE 2. Soluble phosphate levels in the Mississippi River at Bemidji, December 5-31, 1971. Date as µg./1. or ppb. Bemidji in January, 1972. Data expressed as µg./1. or parts per billion. River Miles Number of Average River Downstream Collecting St ation Samples Value Miles Number of Average Sampling Station Downstream Samples Value Above Lake Bemidji Outflow 16 20.8 0 Sewage Effluent 23* 34,100.0 Lake Bemidji Outflow ...... above 13 22. 1 1 mile downstream, N. side 16 79.5 Sewage Effluent ...... 0 12 47,000. 7 Powerdam 12 157.0 Powerdam ...... 7 14 232. 10 Wolf Lake Inlet 9 166.3 Wolf Lake Outlet ...... 15 11 164. 15 Wolf Lake Outlet 8 97.1 Lake Andrusia Outlet ...... 19 12 135. 19 Lake Andrusia Outlet 8 79.3 Pike Bay Inlet to Cass Lake . . 11 18.7 Turtle River Inlet to Cass Lake 13 32.5 *Includes five samples taken in October and November, 1971. Cass Lake Outlet ...... 27 12 18.8 septic systems around this lake was 14.5 Kg./ day if no changes during the year. The city engineer, J. Walker, phosphate adsorption occurred in soils of septic tank and reports an average BOD of 41 mg. / 1. with a range of cesspool leaching fields. Cass Lake and the powerdam 18-100. Again, this parameter does not show variation impoundment appear to trap the majority of soluble consistent with season. phosphate from the municipal effluent of Bemidji. The daily contribution of soluble phosphate to the Mississippi Different terminology suggested River system by the municipal effluent in the period of Since the effectiveness of sewage treatment depends in 17 October to 31 December, 1971, based on an estimated large part on the growth of thermophilic bacteria which flow of 1.1 million gallons per day and an average level strip nutrients from sewage during the treatment process, of 34.1 mg, P04/ l. was 141.79 Kg. soluble P04 per day. perhaps a wintertime rise in soluble phosphate occurs During January, 1972, the contribution was estimated to regularly when severe cold weather lowers treatment tem­ rise to 195.4 Kg. soluble P04 per day. perature. Although Bemidji's plant is designed and classi­ fied as a secondary treatment facility, the variable and Variance in effluent quality poor quality of the effluent suggests that the term "pseu­ Effluent quality at the discharge pipe varied signifi­ do-secondary" would be more appropriate. These data cantly during this study. From levels approximating 25 show clearly that the Bemidji sewage system is the major mg./1. in October and November, the effluent quality contributor of soluble phosphate to the Mississippi River (based on soluble phosphate content) deteriorated mark­ in that area. During the fall months (October through edly to an average of 47 mg./1. in January. In general, December) this sewage outfall added approximately fif­ the Bemidji effluent has significantly higher phosphate teen times as much soluble phosphate to the river as the content than the typica1 municipal secondary effluent: water hd d when leaving Lake Bemidji. In January, the Grundy ( 1971) estimates that the typical secondary ef­ ratio of effluent added to natural soluble phosphate was fluent has 16 mg. soluble P04/ l. and 9 mg. insoluble twenty-one to one.

P04/ l. Turbidity values varied a good deal throughout Several factors suggest that these waters are even more the study, but there was no general winter increase (Ta­ polluted than these data indicate. The fall of 1971 was ble 4). Data on biological oxygen demand (BOD) in one of the wettest on record. For December, 1971, and Pollution Control Agency files do not show regular January, 1972, stream flows for the headwaters region of

TABLE 3. Soluble phosphate and loading factors on the Mississippi River and associated lakes below Bemidji, January, 1972

Contribution Estimated to Downstream Discharge µg./ 1. solublo water in Sampling Station in CFS Phosphate Kg PO,/ day Lake Bemidji Outflow ...... 192. 22 9.39 Municipal Sewage Effluent .... . 1.61 (1.1 mgd.) 47,000 195.43 Mississippi River just below effluent discharge ...... 192. 384* 204.82 Power Dam ...... 220.** 232 123.78 Wolf Lake Outlet ...... 190. * ** 164 80.56 Lake Andmsia Outlet ...... 187. 135 59.47 Turtle River Inlet to Cass Lake .. 94. 32.5 6.90 Pike Bay Inlet to Cass Lake .. . 37. 18.7 0.91 Cass Lake Outlet ...... 502. 18.8 12.28

* Accurate values for the river were not obtainable because of poorly mixed water at this point. **The estimated value of 220 CFS discharge is probably about 10-15% above real dis­ charge because of shallow water and turbulence around the current meter. ***This discharge was not measured because of very thick ice cover, but was estimated from upstream and downstream discharge data of 192 and 187 CFS. Journal of, Volume Thirty-eight, Nos. 2 and 3, 1973 103 TABLE 4. Turbidity in Bemidji sewage effluent TABLE 5. Estimated daily deposition of phosphate in the from December 5, 1971-January 16, 1972. Mississippi River power dam impoundment and lakes be­ low Bemidji, January, 1972. Data expressed as Kg.PO,/ Reading in Reading in Date of Jackson Turbidity Date of Jackson Turbidity day deposited. Sample Units Sample Units Powerdam ~1ississippi 12-05-71 86 12-26-71 44 La ke Impound- Wolf Lake Ri ver below 12-05-71 77 12-27-71 47 Bemidji ment Lake Andrusia Cass Lake Cass Lake 12-07-71 80 12-28-71 100 12-08-71 91 12-29-71 49 Inlet(s) n.d. 204.82 123.78 80.56 67.28 12.28 12-09-71 72 12-30-71 61 Outlet 9.39 123.78 80.56 59.47 12.28 n.d. 12-10-71 78 12-31-71 53 Deposition n.d. 80.56 43.22 21.09 55.0 n.d. 12-11-71 52 1-04-72 56 12-12-71 67 1-06-72 68 (n.d. = no data taken or insufficient data.) 12-13-71 72 1-08-72 44 12-14-71 70 1-13-72 49 arily treated sewage effluent is insoluble. If true for this 12-15-71 79 1-16-72 70 study, then the total phosphate loading is considerably 12-23-71 52 Average value 68 underestimated. It is also important to note that these es­ timates of dispersion and deposition of soluble phosphate the Mississippi River were among the highest ever re­ were made in the winter, when reduced water tempera­ corded. ture and reduced light, because of surface ice, prevented Since the ratios quoted above depend on a dilution fac­ photosynthesis from taking place. Photosynthesis would tor, it is clear that maximum dilution occurred in De­ tend to raise the rate of soluble phosphorus removal dur­ cember, 1971, and January, 1972. In dry years, by con­ ing other times of the year. For example, the PCA report trast, this portion of the river often has no discharge as (1969) on the total phosphate of many summer samples far downstream as the darn. At the from 1966 to 1968 at the Wolf Lake inlet station aver­ Grand Rapids-Blandin Paper Company dam, the Corps aged 338 µ,g. PO4/ 1. compared with the 166 and 232 of Engineers estimate ten-year low flows of 40 CFS, and µ,g. soluble PO4 / 1. obtained in this study. Increased bio­ 30-year low flows of 20 CFS. Presumably, during low logical activity may shorten the recovery phase of the flow years the Mississippi River below Bemidji, and es­ river in the summer months, and further investigation is pecially between Lake Bemidji and the Powerdam, be­ indicated. comes in effect a large oxidation pond for the sewage of Bemidji. References Although the long term effects of the significant load­ ANDERSON, W.R. 1971. The governor's state of the state ing are not fully known, they are not likely to be desir­ message for Minnesota in 1971 . St. Paul, Minnesota. able. Megard's ( 1970, 1972) research on Lake Minne­ ANONYMOUS. Report of Wolf, Andrusia, and Cass Lakes. tonka suggests that entrapped phosphorus is generally Staff report 427, Div. Water Quality, Minnesota Pol­ not readily recycled to surface waters (and phytoplank­ lution Control Agency. ters). He suggests that cessation of sewage discharges to BRYDGES, T. G. 1972. An intensive biochemical survey that lake will result in rapid reversal of eutrophication. A in western Lake Erie. Proc. 14th Conf. Great Lakes recent study (Brydges, 1971) indicates that the already Res. 1971 : 191-197. Internati. Assoc. Great Lakes very severe eutrophication of Lake Erie is ameliorated by Res. sedimentation of phosphorus, although some recharge to CORBETT, D. M. 1962. Stream Gaging Procedures. Wa­ surface waters during summer occurs during oxygen de­ ter Supply Pap. 888. U.S. Geol. Surv. pletion in the hypolimnion in that system. The Mississip­ GRUNDY, R. D. 1971. Strategies for control of man-made pi headwaters lakes regularly experience lowered dis­ eutrophication. Env. Sci. & Tech. 5: 1184-1190. solved oxygen levels in midsummer. Thus while soluble HoL T, C. S. 1971. Patterns of lakeshore usage around phosphates from Bemidji are apparently deposited in the Lake Bemidji. J. Minn. Acad. Sci. 37: 104-108. headwaters lakes during the winter months, the nutrient ME GARD, R. 0 . 1970. Lake Minnetonka: nutrient to nu­ accumulation is partially released in the months when trient abatement, and the photosynthetic system of the hypolirnnion oxygen depletion occurs. The seriousness of Phytoplankton. Interim Rept. 7. Limnol. Res. Center, algal blooms following mixing of these waters probably is Univ. Minnesota, Minneapolis. due in part to released phosphate, especially in the fall of MEGARD, R. 0. 1972. Phytoplankton, Photosynthesis the year. and Phosphorus in Lake Minnetonka, Minnesota. Another problem that should be considered in evaluat­ Limnol. and Oceanogr.: in press. ing these data is that the analyses were performed only SCHINDLER, D. W. 1971. Carbon, nitrogen and phos­ for soluble phosphate. Grundy ( 1971) indicates that phorus and the eutrophication of freshwater lakes. J. roughly 28 percent of the phosphate contained in second- Phycol. 7: 321-329.

104 The Minnesota Academy of Science