TagWater Quality(478)

City of SeaTac Municipal Code section 15.30.340 and King County Code section 21A.24.360 establishing stream development standards and minimum buffer requirements from the ordinary high water mark (OHWM). Specifies buffers for Class 1 streams (100 feet), Class 2 streams used by salmonids (100 feet), Class 2 streams not used by salmonids (50 feet), and Class

This document outlines the Port of Seattle's step-by-step process for applying water quality standards at a specific site, focusing on copper toxicity testing in local waterways. The flowchart guides researchers through a series of studies — including screening, range-finding, and definitive toxicity tests using waterfleas and fathead minnows — to determine whether copper levels in outfall and receiving waters pose environmental risks. Depending on test results and regulatory approval from the Washington State Department of Ecology, the process may lead to a Water Effect Ratio (WER) study or a Translator Study.

Technical Note #15 from Watershed Protection Techniques, I(1):30-31, covering sources of urban stormwater pollutants as defined in Wisconsin. Based on Bannerman, R., D. Owens, R. Dodds, and N. Hornewer (1993) study published in Water Science & Technology (28):3-5, pp. 241-259. Over 300 runoff samples collected from 46 micro-sites in two watersheds. Documents pollutant concentrations of

Technical Note #13 from Watershed Protection Techniques 1(1):28, summarizing a Santa Clara Valley Nonpoint Source Program study on metal pathways into the Lower San Francisco Bay. Cars and vehicles found to produce over 50% of total loads of copper, cadmium, and zinc; brake pad wear alone accounts for 50% of total copper load; tire wear

This document presents a Water Resources Analysis Schedule, displayed as a Gantt-style project timeline chart. It outlines the sequencing and duration of various technical tasks related to water resources analysis, including data collection, feasibility studies, treatment evaluations, and report preparation. The schedule appears to track project milestones and dependencies across multiple phases of a water resources planning effort.

This document outlines Washington State Department of Ecology's presumed policy positions on stormwater mixing zones, addressing when stormwater becomes regulated state water and how mixing zones should be calculated. It details recommended design storms for acute and chronic mixing zones, critical receiving water flow conditions, and background concentration requirements. The document also discusses circumstances under which mixing zone size criteria exceedances may be permitted under state regulations.

This document contains hydrological flow data for Miller Creek, including a ranked frequency analysis of the lowest monthly mean streamflows recorded between August and May from 1948 to 1995, alongside modeled daily and hourly stream flow outputs from 2-year/72-hour and 2-year/2-hour storm events simulated in August 1996. The analysis identifies a 5-year mean low flow of approximately 0.60 cubic feet per second for the lowest month in the August–May period. Acute and chronic water quality standards are also evaluated in relation to effluent and receiving water flows during the storm event.

National Research Council publication by the Committee on Mitigating Wetland Losses, Board on Environmental Studies and Toxicology, and Water Science and Technology Board titled ‘Compensating for Wetland Losses Under the Clean Water Act.’ AR034586, Exhibit-2178. Covers mitigation compliance standards including jurisdictional hydrology, wetland delineation, hydrological performance standards, design standards for mitigation sites, USACE wetland filling

This document presents a statistical analysis of ambient water conditions and effluent discharge at a location designated 3RWN, examining the joint probability of stream flow and discharge occurring simultaneously. It includes a 3D probability surface chart, a data table showing dilution factors ranging from 3.6 to 5,294 at various probability levels, and a distribution curve of ambient stream discharge measured in cubic feet per second. The analysis notes that effluent is present approximately 38% of the time, with the 7Q10 flow of 0.16 cfs corroborating the 1st percentile and the 5Q30 flow of 0.15 cfs corroborating the 0.9th percentile.

This Washington State administrative regulation establishes rules for 'mixing zones,' which are designated areas in bodies of water where pollutant discharges are allowed to mix and dilute before meeting water quality standards. The rules set strict size limits for mixing zones in rivers, estuaries, lakes, and ocean waters, and require that dischargers apply all available pollution-reduction technology before a mixing zone is approved. Special provisions are also included for storm water discharges and combined sewer overflows.