Year Established: 2011 Start Date: 2011-03-01 End Date: 2014-02-28
Total Federal Funds: $59,028 Total Non-Federal Funds: $99,858
Principal Investigators: John Warwick
Abstract: The Truckee River originates from the western shore of Lake Tahoe and flows over the border of California and Nevada heading east until the main stem turns north and terminates in Pyramid Lake. Along its route, water is diverted for agricultural and municipal uses. Upon entering Nevada, the river passes through the Truckee Meadows, a broad valley that contains the Reno-Sparks metropolitan area. Water quality is a serious issue for the Truckee River downstream of Reno-Sparks with frequent high water temperatures and low dissolved oxygen (DO) concentrations during low flow periods, which usually occur in late summer into fall. During periods of low flow, much of the water entering the Truckee via Steamboat Creek is treated effluent from the Truckee Meadows Water Reclamation Facility (TMWRF), which discharges into the creek near its mouth. Hyporheic exchange, the mixing of surface water (SW) and groundwater (GW) beneath and adjacent to streams, can have a significant effect on water quality and aquatic habitat (Gooseff et al., 2006). In this zone, stream water residence times are increased which has a large effect on the fate and transport of solutes (Gooseff et al., 2003). Perhaps the most important function for the Truckee River is the removal of nitrogen through denitrification from the system as periphyton growth in the Truckee River is primarily nitrogen limited (Green, 2002). If hyporheic exchange is increased through current restoration efforts, total periphyton biomass should decrease and the minimum nighttime DO concentrations in the river should increase. Understanding the fluctuations of DO in this system are particularly important for the threatened and endangered habitat of the Lahontan cutthroat trout (threatened species) and cui-ui (endangered species) that historically made spawning runs from Pyramid Lake to the Truckee River (US Fish and Wildlife Service 1992, 1995). Restoration efforts along the Truckee River plan to return the river to more natural conditions including the addition of stream meanders and pool-riffle sequences. Despite the fact that these projects are known to increase hyporheic exchange (Sawyer and Cardenas, 2009), the magnitude of influence towards in-stream water quality does not appear to have been addressed in previous studies. We will use knowledge gained about the hyporheic processes in the Truckee River and the factors controlling them to quantify the relative impact of these restoration efforts on the in-stream water quality.