The modeled and observed response of Lake Spokane hypolimnetic dissolved oxygen concentrations to phosphorus inputs
Creators: name: Brett, Michael T.
name: Ahopelto, Suvi K.
name: Brown, Hunter K.
name: Brynestad, Barton E.
name: Butcher, Titus W.
name: Coba, Emily E.
name: Curtis, Christina A.
name: Jebessa T. Dara
name: Doeden, Kallie B.
name: Evans, Kevin R.
name: Fan, Lu
name: Finley, Josh D.
name: Garguilo, Noah J.
name: Senait M. Gebreeyesus
name: Goodman, Marissa K.
name: Gray, Kenneth W.
name: Grinnell, Crystal
name: Gross, Kathryn L.
name: Hite, Brian R. E.
name: Jones, Andrew J.
name: Kenyon, Philip T.
name: Klock, Angela M.
name: Koshy, Raji E.
name: Lawler, Amanda M.
name: Lu, Man
name: Martinkosky, Luke
name: Miller-Schulze, Jeremy R.
name: Nguyen, Quyen T. N.
name: Runde, Elizabeth R.
name: Stultz, Joanie M.
name: Songlin Wang
name: White, Francesca P.
name: Wilson, Corey H.
name: Wong, Andrea S.
name: Wu, Shirley Y.
name: Wurden, Peter G.
name: Tessora R. Young
name: Arhonditsis, George B.
Publisher: name: Taylor & Francis
Year: 2016
Subjects: subject: Biochemistry
subject: Medicine
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: FOS: Earth and related environmental sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: FOS: Chemical sciences
subject: Ecology
subject: FOS: Biological sciences
subject: FOS: Biological sciences
subject: 69999 Biological Sciences not elsewhere classified
subject: Inorganic Chemistry
subject: 110309 Infectious Diseases
subject: FOS: Health sciences
subject: FOS: Health sciences

description: Brett MT, Ahopelto SK, Brown HK, Brynestad BE, Butcher TW, Coba EE, Curtis CA, Dara JT, Doeden KB, Evans KR, Fan L, Finley JD, Garguilo NJ, Gebreeyesus SM, Goodman MK, Gray KW, Grinnell C, Gross KL, Hite BRE, Jones AJ, Kenyon PT, Klock AM, Koshy RE, Lawler AM, Lu M, Martinkosky L, Miller-Schulze JR, Nguyen QTN, Runde ER, Stultz JM, Wang S, White FP, Wilson CH, Wong AS, Wu SY, Wurden PG, Young TR, Arhonditsis GB. 2016. The modeled and observed response of Lake Spokane hypolimnetic dissolved oxygen concentrations to phosphorus inputs. Lake Reserv Manage. 32:246–258. Lake Spokane, a reservoir in eastern Washington State, was previously hypereutrophic due to phosphorus discharges from the City of Spokane wastewater treatment plant (WWTP). This reservoir subsequently recovered to a meso-oligotrophic state after implementation of advanced phosphorus removal. The present study tested whether the mechanistic Lake Spokane water quality (WQ) model realistically represents the sensitivity of this reservoir's hypolimnetic oxygen concentrations to phosphorus inputs. We compared the observed relationship between the mean summer input total phosphorus concentration (TP<sub>IN</sub>) and the minimum volume weighted hypolimnetic dissolved oxygen concentration (DO<sub>MIN</sub>) to model values for conditions ranging from hypereutrophic to oligotrophic. Prior to advanced phosphorus removal, TP<sub>IN</sub> and DO<sub>MIN</sub> averaged 86 ± 37 (SD) µg/L and 1.4 ± 1.3 mg/L, respectively. Currently (2010–2014), these values average 14 ± 3 µg/L and 6.5 ± 0.8 mg/L, respectively. By contrast, the model's DO<sub>MIN</sub> response for similar TP<sub>IN</sub> concentrations was much less pronounced, with hypereutrophic and contemporary DO<sub>MIN</sub> averaging 3.8 ± 0.4 and 4.7 ± 0.04 mg/L, respectively. The model also has a structural DO deficit (saturated DO − DO<sub>MIN</sub>) of 5.3 mg/L that was evident when all TP inputs to the reservoir were set to zero. Similarly, when all WWTP effluent sources were set to TP<sub>EFF</sub> = 0 µg/L, the reservoir epilimnetic TP concentrations were ≈8 µg/L higher than the Spokane River inputs. The water quality model indicates that even if effluent phosphorus concentrations are reduced to zero, the dissolved oxygen goals for Lake Spokane cannot be met.