Water Quality and Fish Habitat in Littoral Macrophyte Beds Sample Clauses

Water Quality and Fish Habitat in Littoral Macrophyte Beds. Macrophyte (aquatic plant) beds are the second most abundant cover type observed in the in the Reservoir during aquatic habitat mapping (DES, 2001a). At 220,000 cfs flows, cover habitat comprised 16% of the wetted area represented by transects, with boulders accounting for 90% of the cover, with submerged aquatic vegetation and terrestrial grasses providing the remaining cover. At lower flows, only the boulder and aquatic vegetation cover types are available. Macrophyte beds occurred in shallow, near-shore environments throughout the length of the Reservoir. Large macrophyte beds extended well out from shore in the vicinity of Turtle Rock Island and areas approximately 2.5 miles and about 4.5 miles north of Turtle Rock Island. Large macrophyte beds extend out to mid channel in an area just downstream of Daroga Park. The total area of macrophyte beds in the Project boundary, including pools isolated from the Reservoir by highways, was 386 acres in 1999. The most abundant macrophyte species were Eurasian watermilfoil (the dominant species in 30% of the beds), native pondweeds and curly pondweed, in that order (DES, 2001a). Macrophyte beds are important habitat for a variety of fish species, providing both food and cover. The juveniles of most of the species of resident fish that were abundant in the Reservoir were observed to use macrophyte beds as habitat (DES, 2001b). Although sampling in macrophyte beds was not extensive, Chinook salmon were observed using macrophyte beds in the Reservoir (Xxxx Xxxx, EES (formerly DES), personal communication). Areas that are shallow, with low flow velocities and dense macrophyte growth, are where water quality exceedances are most likely to occur. However, these areas also provide suitable habitat for Chinook salmon, the primary sensitive species that would use this habitat type. The aquatic habitat map layers (DES, 2001a) have been processed to show the locations where these three habitat features (shallow – less than 10 feet deep, velocities less than 0.1 feet per second, with dense macrophyte growth) are present (Appendix D). DO levels in dense macrophyte beds may fluctuate widely throughout the day, at times falling below the water quality criterion of 8.0 mg/L. During the day, aquatic plants produce oxygen while undergoing photosynthesis, which results in high DO levels that can exceed saturation levels. However, at night the macrophytes consume oxygen during their respiration cycle, and DO levels can drop below 8.0...