Spring 4A is located on the west side of the Rio Grande, approximately .5 mile upstream from the river.

Field Parameters: No specific conductance measurements taken; pH 8.02 at 20° C.
Flow:
Coordinates: NMED - DGPS: 1656092.93 1747951.27
Elevation: NMED - DGPS: 5571

Sampling on Thursday, May 1, 2003 in the morning.

• LANL/WQH took a 250 ml water sample for low-level perchlorate testing by the LC/MS/MS method.
  
• NMED helped LANL collect their samples. NMED took a 1 L water sample for the NMED Groundwater Bureau for nitrogen species, trace metals and anions and cations.
  
• TRAC collected moss samples, both washed and unwashed. They collected a sediment sample from the moss and from the streambed. TRAC also collected two 40-liter water samples for sampling of all radionuclides except carbon-14 and tritium.