Management of aquatic resources requires meaningful assessment endpoints on which to base decisions. In freshwater streams, assessment endpoints are often defined as fish communities. Given the limited resources available for environmental monitoring, having a means of predicting fish assemblages in streams where no sampling has yet occurred would be useful. Such a tool could be used for regional screening‐level analyses of fish communities and could be input into local‐scale model applications for evaluating management scenarios of stream degradation or restoration. In this study, a set of fish assemblages (a list of fish species and their corresponding relative abundances) representative of different stream types in the Mid‐Atlantic Highlands region of the United States was defined by use of a k‐means cluster analysis performed on relative abundance estimates. The cluster analysis produced 18 fish assemblages, and the following 14 species had the greatest relative abundance in at least one of the 18 assemblages: Eastern blacknose dace Rhinichthys atratulus, bluehead chub Nocomis leptocephalus, bluntnose minnow Pimephales notatus, brook trout Salvelinus fontinalis, central stoneroller Campostoma anomalum, creek chub Semotilus atromaculatus, fantail darter Etheostoma flabellare, mottled sculpin Cottus bairdii, mountain redbelly dace Phoxinus oreas, redbreast sunfish Lepomis auritus, rosyside dace Clinostomus funduloides, slimy sculpin Cottus cognatus, striped shiner Luxilus chrysocephalus, and white sucker Catostomus commersonii. A discriminant analysis was then used to predict a stream's potential fish assemblage based on stream and watershed characteristics. The discriminant function had a 42% success rate using the following predictors: Latitude, longitude, mean stream depth, percent urban area of the watershed, and percent fine gravel on the stream bottom. The discriminant function was validated with an independent data set from a regional data collection effort in West Virginia, resulting in 44% success when classifying observed stream fish communities.

Fracturing work conducted on the 2006 Tip Top/Hogsback (TTHB) field horizontal well program proved that sand plug isolation will work in horizontal wells, even when the stimulation treatment calls for fracturing with a high energy fluid. The TTHB field is a tight gas field in southwestern Wyoming, and the wells will not produce without a fracture stimulation treatment. This paper will describe the evaluation process of various fracturing technologies considered for the program, and how learnings from a 1995 horizontal program were used to build the final pinpoint stimulation design. In addition, this paper will discuss the stimulation execution and the learnings generated from the program. The fractured horizontal wells were drilled to 11,000 ft measured depth (MD), 7,200 ft true vertical depth (TVD), with the laterals being approximately 3,800 ft of the total measured depth. Eight fracture treatments were planned for each horizontal. The foam stimulation treatments contained 60-quality CO2 and averaged 235,000 lbm total proppant per zone. The basic stimulation procedure consisted of cutting perforation holes by use of a hydrajet tool on the end of coiled tubing (CT), pumping a fracture treatment down the production casing, and setting a sand plug with CT in the lateral to provide zonal isolation. This process allowed continuous treatment of successive intervals without shutting down to set a mechanical plug or perforate the next interval. Although several challenges were encountered during the execution of the stimulation treatment, the stimulation design did prove to be a more time efficient and cost effective option than conventional horizontal well fracturing treatments. The paper will discuss learnings on setting sand plugs between fracs, frac designs, and equipment operation/limitations. As a result of the learnings, the average treatment time decreased from 24 hr/zone on the first well to 13 hr/zone on the second. The paper will also discuss additional changes made during the stimulation execution to increase the effectiveness of the hydrajet tool and increase the probability of setting a successful sand plug. The process for designing and placing successful sand plugs was optimized from well to well and can furthermore be tailored to fit other fields. Learnings and techniques applied in this work can be used to improve and optimize fracturing treatments of similar nature in other geographic/geologic areas. Introduction The TTHB field is a tight gas field in southwestern Wyoming (Fig. 1) which has been produced since 1953. Production is primarily from relatively shallow, normal pressure, sweet gas formations. Based on the nature of these tight gas sands, TTHB wells will not produce without hydraulic fracturing. Formation properties are listed in Table 1.

Numerous models have been developed to predict the bioaccumulation of organic chemicals in fish. Although chemical dietary uptake can be modeled using assimilation efficiencies, bioaccumulation models fall into two distinct groups. The first group implicitly assumes that assimilation efficiencies describe the net chemical exchanges between fish and their food. These models describe chemical elimination as a lumped process that is independent of the fish's egestion rate or as a process that does not require an explicit fecal excretion term. The second group, however, explicitly assumes that assimilation efficiencies describe only actual chemical uptake and formulates chemical fecal and gill excretion as distinct, thermodynamically driven processes. After reviewing the derivations and assumptions of the algorithms that have been used to describe chemical dietary uptake of fish, their application, as implemented in 16 published bioaccumulation models, is analyzed for largemouth bass (Micropterus salmoides), walleye (Sander vitreus ϭ Stizostedion vitreum), and rainbow trout (Oncorhynchus mykiss) that bioaccumulate an unspecified, poorly metabolized, hydrophobic chemical possessing a log K OW of 6.5 (i.e., a chemical similar to a pentachlorobiphenyl).

Craig Barber MBCS CITP tells ITNOW how to overcome challenges with security operations teams in a large organisation.

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