Stewart Rounds (Former Employee)

A previously calibrated two-dimensional hydrodynamic and water-quality model (CE-QUAL-W2) of Detroit Lake in western Oregon was used in conjunction with inflows derived from Precipitation-Runoff Modeling System (PRMS) hydrologic models to examine in-lake and downstream water temperature effects under future climate conditions. Current and hypothetical operations and structures at Detroit...

Significant Findings A large bloom that included floating mats of the blue-green algae Anabaena flos-aquae occurred in the lower 20 miles of the Tualatin River in northwestern Oregon between July 7 and July 17, 2008. The floating bloom was deemed a hazard to recreational users of the river due to the potential production of algal toxins (anatoxin-a and microcystin), and a public health...

Water temperature models of Detroit Lake, Big Cliff Lake, and the North Santiam River in northwestern Oregon were used to assess the potential for a hypothetical structure with variable intake elevations and an internal connection to power turbines at Detroit Dam (scenario SlidingWeir) to release more natural, pre-dam temperatures year round. This hypothetical structure improved outflow...

Water-quality models allow water resource professionals to examine conditions under an almost unlimited variety of potential future scenarios. The two-dimensional (longitudinal, vertical) water-quality model CE-QUAL-W2, version 3.7, was enhanced and augmented with new features to help dam operators and managers explore and optimize potential solutions for temperature management...

The term organic matter refers to the remnants of all living material. This can include fallen leaves, yard waste, animal waste, downed timber, or the remains of any other plant and animal life. Organic matter is abundant both on land and in water. Investigating organic matter is necessary for understanding the fate and transport of carbon (a major constituent of organic matter). Organic...

For this study, we explored the amount, type, and distribution of foliar biomass that is deposited annually as leaf litter to Fanno Creek and its floodplain in Portland, Oregon, USA. Organic matter is a significant contributor to the decreased dissolved oxygen concentrations observed in Fanno Creek each year and leaf litter is amongst the largest sources of organic matter to the stream...

Organic matter (OM) is abundant in Fanno Creek, Oregon, USA, and has been tied to a variety of water-quality concerns, including periods of low dissolved oxygen downstream in the Tualatin River, Oregon. The key sources of OM in Fanno Creek and other Tualatin River tributaries have not been fully identified, although isotopic analyses from previous studies indicated a predominantly...

The sources, transport, and characteristics of organic matter (OM) in Fanno Creek, an urban stream in northwest Oregon, were assessed and quantified using: (1) optical instruments to calculate transported loads of dissolved, particulate, and total organic carbon, (2) fluorescence spectroscopy and stable isotope ratios (δ13C, δ15N) to elucidate sources and chemical properties of OM...

The upper Klamath River and adjacent Lost River are interconnected basins in south-central Oregon and northern California. Both basins have impaired water quality with Total Maximum Daily Loads (TMDLs) in progress or approved. In cooperation with the Bureau of Reclamation, the U.S. Geological Survey (USGS) and Watercourse Engineering, Inc., have conducted modeling and research to inform...

Flow and water-quality models are being used to support the development of Total Maximum Daily Load (TMDL) plans for the Klamath River downstream of Upper Klamath Lake (UKL) in south-central Oregon. For riverine reaches, the RMA-2 and RMA-11 models were used, whereas the CE-QUAL-W2 model was used to simulate pooled reaches. The U.S. Geological Survey (USGS) was asked to review the most...

The Link River to Keno Dam (Link-Keno) reach of the Klamath River, Oregon, generally has periods of water-quality impairment during summer, including low dissolved oxygen, elevated concentrations of ammonia and algae, and high pH. Efforts are underway to improve water quality in this reach through a Total Maximum Daily Load (TMDL) program and other management and operational actions. To...

Phytoplankton populations in the Tualatin River in northwestern Oregon are an important component of the dissolved oxygen (DO) budget of the river and are critical for maintaining DO levels in summer. During the low-flow summer period, sufficient nutrients and a long residence time typically combine with ample sunshine and warm water to fuel blooms of cryptophyte algae, diatoms, green...