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DESIGNING IMPACT ASSESSMENTS FOR EVALUATING ECOLOGICAL EFFECTS OF AGRICULTURAL CONSERVATION PRACTICES ON STREAMS 0 C A 191 FIGURE 2. Schematic Depicting Locations of Six Permanent Transects Within a 125 m Long Site for Sampling Geomorphology, Riparian Habitat, and Instream Habitat (A). Transects encompass the Riparian Zone (RZ), Aquatic Habitat (AH), and end at the Agricultural Field (AF). Riparian habitat characteristics are measured along each transect and within 1 m x 10 m quadrats located upstream of the transects (B). Geomorphology measurements are taken within the left and right top banks along the transects (Q. Measurements of instream habitat characteristics are collected at four equidistantly spaced points along each transect within the aquatic habitat (D). percent substrate types involve an investigator walk- ing a reach and then estimating the percent of sub- strate and instream habitat features. Instantaneous discharge is measured using a wading rod and cur- rent meter at an additional transect within each site. Water chemistry characteristics are measured in situ or by analysis of grab samples. Water samples collected from weekly grab samples obtained from May to December are analyzed for nutrients, herbi- cides, and total suspended solids. In situ measure- ments of dissolved oxygen, temperature, pH, and conductivity are obtained with a multiparameter meter from one location within a site three times a year concurrently with instream habitat, fish, and macroinvertebrate sampling. Grab samples for tur- bidity measurements are collected in conjunction with in situ measurements. Fishes and macroinvertebrates are sampled three times a year concurrently with instream habitat and in situ water chemistry measurements. Block nets are set at the upstream and downstream borders of the sites prior to sampling fishes and macroinverte- brates. Fishes are sampled with a backpack electro- fisher and seine. Electrofishing begins at the downstream border and proceeds upstream. After electrofishing, five seine hauls are conducted and dis- tributed throughout a site. Pools and slow flowing areas are sampled with a haul and fast flowing riffle areas are sampled using the seine as a block net and kicking into the seine. The seining effort is standard- ized by ensuring each haul or kick sample encom- passes a 4 m length of shoreline. This provides flexibility to use the best methods for sampling a given habitat type and ensures that sampling efforts are standardized. Macroinvertebrates are sampled with dipnet and surber samples after completion of fish sampling. Sampling is conducted to ensure that sampling efforts are distributed throughout the site and that collec- tions are obtained from each habitat unit (i.e., pools, riffles, runs) present in a site. Three dipnet samples are collected from areas that are either too deep or JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION 875 JAWRA