Resolution No. 4793 - Laserfiche WebLink

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MWMC FACILmE$ PLAN In adclition, management staff anticipate that the WPCF will not be a sigrdficant thermal load source under the biologically based numeric criteria of 55.4 °F (13 °C) £or salmon and steelhead spawning from October 15 tlxrough May 15, and a human use allowance temperature increase of 0.5 F° (0.3 C~). To put the water temperature data in perspective, in general, the coo~ess of water at night has some bearing on the ability of cool-water fish to withstand ma×imva-n water temperatures dur~g the day. Because fish are cold-blooded, their energy needs increase with increasing water temperature. Trout usually leave water that regularly exceeds 70° F during the day. Rivers and streams with Iow water temperature at rdght enable fish to rejuvenate and be better prepared for the next day's increased water temperatures. Bacteria Monitor~mg for E. coli in the Willamette River in the MWMC service are has occurred over a number of years and for a large number of sites. The mainstem o£ the Willamette River had no exceedances of the state water quality standard. Currently, Escherichia coli (abbreviated as E. colO is widely used to evaluate the level o£ harmbal bacterial contamination in water. In Oregon, the water quality standard £or E. cdi ~s 406 orga~dsms/100 m~ll~liter (mL) to protect swimming and aquatic life; the drinking water standard is <1 orgardsms/100 mL. These organisms, along with other, more harmful types, have their origin in the intestinal tracts of humans and some ardmals. While E. co[i counts alone do not measure contamination risk for humans, they are indicative of stormwater quality entering rivers and streams. Perhaps more importantly, they are indicators of potentially more significant water quality issues that are generally associated with land development. Although naturally occurring bacteria in streams generally have no affect or~ fish, other aquatic orgardsms, or wildlife, certain types of bacteria or high concentrations may pose a health risk to people through recreational contact with the water. In addition to bacteria, other water-borne protozoa and d~sease-causing microorganisms can adversely affect human and animal health. Because of the number of various organisms with the potential to affect health, mordtor~g commonly focuses on easily-detected but relatively harmless bacterium that frequently occur with the other, more harmful varieties. Heavy Uetals Heavy metal concentrations in Oregon streams and rivers are generally well below water quality standards. Where concentrations above water quality standards are found, it is usually a result of contamination from human sources, such as industrial sites, paved surfaces, mining operations, galvanized metal siding and roofs on buildLngs, and water trea~ent plants. Aquatic insects and algae are organ~sm_s most affected by high concentrations of heavy metals, ~y of which readily adhere to sediment particles so they may not appear in the water column except at short distances downstream from their SOurCe. With few exceptions, heavy metal concentrations in the Willamette River are, on average, less than the water quality criteria specified by DEQ. In many instances, the concentrations are several orders of magnitude less than the criteria. Water quality data in the IVIWMC 2-20 MWNtC_20_REV23 DOC