SPoT sites are selected in large watersheds with heterogeneous land cover, and are located at or near the base of the watershed, defined as the confluence with either an ocean, lake, or another stream of equal or greater stream order; and located where site-specific conditions are appropriate for the indicators selected (e.g., depositional areas, sufficient flow, appropriate channel morphology, substrate).
Darker areas on the map indicate sub-watersheds. |
Sediments collected from depositional areas at integrator sites provide a composite record of pollutants mobilized from throughout the watershed. While many hydrologic, engineering, and environmental variables affect the ability of this record to adequately characterize all pollutant-related activities, sediment samples collected from such areas are considered to be a relatively good and logistically feasible means of assessing large watersheds for long-term trends
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As of 2020, there was no significant trend in the Hyalella survival endpoint. Although some contaminant concentrations have significant upward and downward trends at individual sites, sites that have been consistently toxic or highly toxic tend to remain so. Sites with toxic and highly toxic sites, as indicated by the X's, demonstrate that beneficial uses are being impacted. The lack of a significant toxicity trend at the statewide level makes it difficult to determine if conditions are getting better or worse.
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