48D070 - Twisp River nr Mouth

48D070 - Twisp River nr Mouth

Results that exceed water quality criteria or the usual range of data (since October, 1996)

Results that exceeded water quality standards criteria

The Department of Ecology places limits on how much pollution is allowed in our rivers to protect public health and enjoyment, and to support fish, shellfish, and wildlife (WAC 173-201A). Individual results for temperature, pH, oxygen, fecal coliform bacteria, and metals (where sampled) that are higher than these criteria are listed below. (The standards do not contain criteria for other types of water quality constituents.) This table includes only results from our monthly monitoring program. Results from other monitoring, such as continuous monitoring for temperature, are not evaluated here.

Exceeding a criterion does not necessarily mean the water quality standard has been violated. Often, other “pollution” conditions must exist for a stream segment to be in violation of water quality standards. In some cases, standards require that the source of pollution be human activities rather than natural causes. Also, more than a single result exceeding a criterion may be required.

Washington's Water Quality Standards were amended in November, 2006. Data in the tables below are based on the older standards through 2008. Data collected after 2008 are based on the ammended standards, excluding supplemental temperature criteria. We are currently working on incorporating supplemental temperature criteria into our evaluation procedures.

Results that contrast strongly with historical data

Results exceeding the usual range of data (defined as 2 standard deviations beyond the mean value for a station based on data from the same three-month period over the previous six years) are shown below. A certain percentage of results will always be listed in this report. Inclusion here does not necessarily indicate something unique is occurring in the watershed.

Historical outliers were not found.