Sentinel Site Criteria

1. Parameters of interest (do not all have to occur at a single site)
   1. Nitrate
   2. TN
   3. Total Phosphorus
   4. Dissolved Phosphorus
   5. Turbidity
   6. Sediment (If viable. Likely few sites available)
2. Site Criteria
   1. Data / Measurements
      1. Longest record available, at least including baseline of 1980-1996 or close to it.
      2. Monthly sampling first, then look at quarterly
      3. Discreet and Continuous sensor data should not be mixed unless an analysis is done to determine if data is comparable
      4. Event data, if available, can be used with certain cautions
      5. If methods vary between sites, can still compare as long as an approved method used, and parameter reported is the same
      6. When using WRTDS, flux bias statistic should be in range of -0.1 to 0.1. Other model checks should be run as well
      7. Flow measurements(discharge) should be available either at the site, or close by on the waterway, to be used to calculate loads
      8. Data gaps should be relatively short, no more than one to two years- use as screening criteria to select sites with shortest data gaps
   2. Geographic
      1. Between approx. 1000 sq. mi to 20,000 sq. mi (no smaller than HUC 8, approximately size of HUC 6)
         1. HUCs not necessarily the size of the watershed.
         2. Drainage for site should be specifically calculated and mapped
      2. Watershed land use should be approximately representative of the state’s land use
      3. Small watersheds (HUC 12 size) can be used to underlie the matrix of larger watersheds to help elucidate more local trends or help explain larger trends
      4. Sites experiencing backwater flow should generally be avoided
3. Methods - WRTDS
   1. Loads
   2. Flow-Normalized Loads & Trends

Selected Sentinel Sites

Each sentinel site will have a separate page. This section will summarize the sites.