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Elevated nitrate levels in streams and groundwater pose human and ecological threats. The U.S. EPA, USGS, Institute of Ecosystem Studies, and Baltimore County Department of Environmental Protection are collaborating on a multi-year study of the impacts of stream restoration on nitrogen processing in Minebank Run, a Piedmont stream in Baltimore County, Maryland. The study is designed to investigate the nitrate removal capacity of this stream before and after restoration. Restoration techniques such as bank reshaping , bank reinforcement, and energy dissipation structures will be constructed to reestablish geomorphic stability lost due to impacts from storm water runoff. We will quantify the effects of specific restoration techniques on microbial denitrification, a process that removes nitrate but which requires anaerobic (saturated) conditions and adequate supply of dissolved organic carbon from detritus and organic soils. Restoration may enhance denitrification by increasing groundwater saturation and/or by increasing carbon supply to denitrifers in the subsurface. Therefore, stream geomorphology, surface flow, groundwater flow, and geochemistry are being quantified throughout the stream reach and in a network of 51 wells and piezometers installed at the site corresponding to the restoration techniques of interest. Denitrification activity will be measured Mayer is an Ecologist and Striz is a Hydrologist,. throughout the stream and related to limiting factors such as dissolved organic carbon and dissolved oxygen. 3-D hydrologic models of nitrate movement will be developed for the watershed. Our study results will be used to develop stream restoration approaches for reducing nitrate pollution in urban watersheds.

– We studied diel microhabitat use at the focal point of age‐0 bull trout, Salvelinus confluentus, in Indian Creek, Washington during mid‐summer and fall of 1997. Microhabitat variables included water depth and velocity, distance from the stream bottom, habitat and refuge use, substrate type, and substrate embeddedness. Age‐0 fish were located over fines and gravel substrates in shallow, low‐velocity water near stream margins, but were located in shallower water at night. Bull trout were highly associated with loose substrate, and used the substrate interstices for refuge cover. Diurnal bull trout counts decreased and no age‐0 fish were observed after 15 September at water temperatures below 6.1 °C. Nocturnal counts remained relatively constant throughout the study. Our results suggest that age‐0 bull trout surveys be conducted at night when summer water temperatures begin to decline.

Three lakes were repeatedly sampled at night using boat electric fishing, experimental gill netting, and fyke netting from May to November 1993 to evaluate the feasibility of using proportional stock density (PSD) to monitor warm‐water fish populations in Washington State, USA. Additionally, average night‐time boat electric fishing catch‐per‐effort of largemouth bass, Micropterus salmoides (Lacepéde), from 30 Washington lakes was also analysed to determine the amount of effort required to obtain adequate samples for precise PSD estimates. Temporal variations in PSD were not large enough to affect the management of warm‐water fish populations in the small Washington lakes studied. However, the considerable effort required to obtain precise PSD estimates may limit its usefulness for warm‐water fisheries surveys in the Pacific Northwest. On average, from three to 13 nights of electric fishing effort are needed to capture enough stock‐length largemouth bass for PSD estimates, depending on the precision desired (80–95%) and the location of the lake (eastern or western Washington). Catch of stock‐length fish can be maximized by using electric fishing for centrarchids and gill netting for yellow perch, Perca flavescens (Mitchill), in June or September. Adequate samples for precise PSD estimates can be difficult to obtain from Pacific Northwestern lakes, even when using recommended gear at optimum sampling times. Inability to capture an adequate sample size for precise PSD estimates may be responsible for some of the fluctuation in PSDs in some studies of warm‐water fish populations in northern areas. Managers in other northern climates may find that low sample size may account for large variations in PSDs reported.

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