Modeling the water-quality effects to the Klamath River from recirculation in drains and canals, Oregon and California, 2006–15

First posted August 25, 2023 For additional information, contact: Director, Oregon Water Science CenterU.S. Geological Survey601 SW 2nd Avenue, Suite 1950Portland, OR 97204 The potential recirculation of Klamath Strait Drain (hereafter called by its local name, “Klamath Straits Drain”) water into Ady Canal to reduce the drain discharge high nutrient loads River was assessed U.S. Survey for Bureau Reclamation. To study feasibility recirculation, this investigation evaluated three scenarios over a 10-year period from 2006 2015, as series 1-year model simulations. A combination two existing hydrodynamic, water-temperature, and water-quality models (CE-QUAL-W2) were used, including (1) Link-Keno reach River, using tributary calendar years 2006–11, (2) same used 2012–15 in with an independent 2012 2015. Model simulations configured base case conditions different sets scenarios: maximum year-round without limits (scenario 1), limited fixed current pipe flow configuration 2), seasonal (May–September) also 3).In case, estimates annual average daily total nitrogen phosphorus exported much 3,060 457 pounds per day (lbs/day), respectively. Currently (2023), Total Maximum Daily Loads allocations are 21 268 lbs/day nitrogen, respectively, so these exceed greater than order magnitude. With scenario 1, load reductions occurred all constituents (total phosphorus, 5-day biochemical oxygen demand [BOD5], carbonaceous demand) discharging River. Scenario 2 had large BOD5 loads. Substantial did occur 3 but constrained only active May through September. Despite restricted period, 32.1 percent 26.5 percent, respectively.The diverts loading tradeoffs between no calculated. On basis, overall net balance resulted more most years. In contrast, higher years.With scenarios, optimal periods benefit Canal, not always coincide. Recirculation would be effective at reducing toward Load spring (March–May) each year. However, during months increase salinity Canal. summer, allocations, though could decrease quality mostly because decreased withdrawals avoided early when concerns highest, while still decreasing summer months.