Water Quality in the Willamette Basin

National Water-Quality Assessment Program

Description of the Willamette Basin Surface Water Trends Network

Willamette Basin surface water fixed sites (FS) were sampled from April 1993 through August 1995 as part of the high-intensity phase of Cycle I. Surface water trends sites (TS) will be sampled from October 2001 through September 2005 as part of Cycle II. Following are brief descriptions of the sites. (See glossary of terms following the list for an explanation of site acronyms and types.) Click on the site name (or activity) to view a photograph. [Photos by D. A. Wentz; files are gif images that range from 75K to 195K]

• Willamette River at Portland (14211720) --
  DA=11,200 sq. mi
  Former NASQAN site with supplemental NAWQA sampling during Cycle I to bring to level of INT BFS; Cycle II TS

• Tualatin River at West Linn (14207500) --
  DA=709 sq. mi.
  Former NASQAN site with supplemental NAWQA sampling during Cycle I to bring to level of INT BFS

• Fanno Creek at Durham (14206950) --
  DA=31.0 sq. mi.
  Cycle I urban IND IFS; Cycle II TS

• East Fork Dairy Creek near Meacham Corner (14205400) --
  DA=~35 sq. mi.
  Cycle II REF IND TS

• Gales Creek near Glenwood (14203750) --
  DA=7.34 sq. mi.
  Cycle I REF IND BFS

  Collecting benthic macroinvertebrates at Gales Creek

• Pudding River at Aurora (14202000) --
  DA=487 sq. mi.
  Cycle I agricultural IND/INT IFS

  Sampling for pesticides at the Pudding River

• Zollner Creek near Mount Angel (14201300) --
  DA=15.0 sq. mi.
  Cycle I agricultural IND IFS; Cycle II TS

• Little Abiqua Creek near Scotts Mills (14200400) --
  DA=9.84 sq. mi.
  Cycle I REF IND BFS; Cycle II TS

  Logging old growth may affect water quality and ecological conditions in the Little Abiqua Creek watershed

Glossary of Terms:

Basic Fixed Sites, Intensive Fixed Sites, and Trend Sites

• Basic Fixed Site (BFS) (Cycle I term) -- Continuous record for discharge, water temperature, and specific conductance; sampled approximately monthly for pH, dissolved oxygen, major cations and anions, dissolved and suspended nitrogen and phosphorus species, dissolved and suspended organic carbon, and suspended sediment; an additional two to three samples collected during high streamflow.

• Intensive Fixed Site (IFS) (Cycle I term) -- BFS with
  1. the addition of approximately 80 dissolved pesticides for each sample, and
     
  2. three to four high-flow samples, instead of two to three.

• Trend Site (TS) (Cycle II term) -- New name for fixed sites. Sampling frequencies and analytical schedules are slightly different than those for Cycle I. The primary differences are:
  1. Samples are collected at regularly scheduled intervals (weekly, biweekly, or monthly), rather than being tied to streamflow;
  2. Pesticide degradation products are analyzed at agricultural and urban IFS; and
  3. VOCs are analyzed at urban IFS.

• Indicator Site (IND) -- Site representing a small drainage basin (10s to 100s of sq. mi.) with relatively homogeneous land use (agricultural or urban).

• Reference Site (REF) -- IND representing a basin with predominantly forested land.

• Integrator Site (INT) -- Site representing a large drainage basin (100s to 1,000s of sq. mi.) with mixed land use.

• DA -- drainage area.

• NASQAN -- National Stream-Quality Accounting Network.