The monitoring plan relies on the use of the following techniques: flow monitoring, water quality monitoring, sediment quality monitoring, biotic tissue sampling, community analysis, toxicity testing, and bioaccumulation analysis. Subsections 4.2 through 4.6 describe in detail the methods by which each of these monitoring techniques is applied.

Flow monitoring will achieve several objectives: 1. to determine compliance with flow limitations in the GBP; 2. to calculate, in combination with total selenium measurements, selenium loadings within the study area; 3. to calculate, in combination with boron and salinity measurements, boron and salt loading within the study area; and 4. to assess overall trends in the area's hydrology attributable to the GBP. Three separate flow monitoring devices/methods will be used, depending on the sampling location, the level of accuracy required, and the physical attributes of each site. These include an acoustic Doppler sensor in combination with a pressure transducer, a sharp-crested weir, and a simple stage reading using a rating curve.

Water quality monitoring will achieve the following objectives: 1. to calculate, at locations where flow measurements are also taken, selenium loadings within the study area; 2. to calculate, in combination with flow measurements, salt and boron loadings within the study area; 3. to assess spatial and temporal trends in water quality parameters of concern; 4. to characterize the habitats in which biotic samples are collected; and 5. to assess the selenium flux within water, sediment and biota. Either automatic composite samples, grab samples, or depth - width integrated samples will be used depending on the sampling location, the level of accuracy required, and the physical attributes of the site.

Sediment monitoring will accomplish several purposes. For compliance, it will be used to determine the quality and quantity of sediment residing in the SLD so as to make appropriate sediment management decisions. The four substations in the SLD will be sampled to determine whether sediment selenium concentrations are approaching a level requiring action (i.e., removal of sediment for disposal). Sediment monitoring will achieve other objectives: 1. to assess spatial and temporal trends in sediment quality parameters of concern; 2. to characterize the habitats in which biotic samples are collected; and 3. to assess of selenium flux within water, sediment, and biota.

Tissue sampling will achieve several objectives: 1. to assess spatial and temporal trends in selenium and boron biotic uptake; 2. to assess selenium flux within water, sediment, and biota; and 3. to assess "adverse environmental impact." Tissue samples will be collected from fish, invertebrates and plants. Avian eggs will also be collected should invertebrate selenium concentrations indicate substantial bioaccumulation. Fish sampling will be conducted using either seine nets or electrofishers, depending on the station location and the conditions at each site. Fish will be inspected for gross tumors and separated into game and non-game categories. Invertebrate sampling will be conducted using a dip net or kick net for aquatic insects and for crayfish. Plant material will be collected by hand. A simple community structure analysis will be conducted using the samples collected by these means.

Toxicity testing will achieve the following objectives: 1. to assess spatial and temporal trends in toxicity; and 2. to assess adverse environmental impact. Laboratory short-term chronic toxicity screening tests will be conducted using three species (alga, invertebrate, and fish) to evaluate both lethal and non-lethal endpoints. If significant toxicity is observed, definitive tests (dilution series) will be run quarterly. In addition, in-situ chronic toxicity tests will be conducted quarterly using caged fathead minnows.

As a part of the algal toxicity test, selenium concentration in control and test algae will be analyzed by USFWS to indicate occurrence of selenium bioaccumulation.