Samples were originally kept cold until filtered within several days of collection, and since 2002 have been filtered immediately in the field.   Filtered samples were frozen until analysis. Particulate samples are filtered in the lab using vacuum filtration., and TSS is calculated from  the mass of particulates  per volume of  sample.  Particulate C and N mass was calculated by analyzing the filters using a CHN analyzer, and converted to concentration by dividing by the filtered volume.  Analysis was conducted at UNH either by the lab of Ted Loder (samples with grid-code = UNH_Grab) at MBL (grid-code = Sigma Grab and Lab_ID = NA) or at UNH by the lab of Bill McDowell (grid-code = Sigma Grab and Lab_ID = McDowell Lab, starting in 2014, unique sample IDs used by the McDowell Lab are entered).  Samples analyzed at the McDowell Lab below the detection limit were entered as 0.  The detection limit is 5 µg/L for  NH4 (0.36 µM) , PO4  (0.16 µM) and NO3 (0.36 µM).

Samples were analysed using Lachat methods.

RESEARCH LOCATION: x and y coordinates given below are in MA State Plane NAD83 (meters). Sites were georeferenced to a gridded river network with 120m grid sizes. X and Y coordinates reflect slight shifts to ensure proper placement on the digital river network. Contributing area is listed in km2.

RESEARCH LOCATION:  x and y coordinates given below are in MA State Plane NAD83 (meters).  Sites were georeferenced to a gridded river network with 120m grid sizes.  X and Y coordinates reflect slight shifts to ensure proper placement on the digital river network.  Contributing area is listed in km2.

Permanent_ID                              Site X                             Site Y                          Description                                 Site ID in SigmaNutrients

YSI-SB                                          225840                          919310               Suburban Headwater Stream                                SB
YSI-CC                                          247680                          946790               Forested Headwater Stream                                CC
YSI-CS                                                                                                           Wetland Headwater Stream                                  CS
YSI-IR                                            232080                          923630               Upper Ipswich R.                              
YSI-FB                                           240600                          934310               Fish Br.                                     
IP24                                                254280                          936350               Mouth of the Ipswich (Sylvania Dam)                   ID
10                                                  246600                          944510                Mouth of the Parker (Central St.)                         PD