Additional text about pH and specificConductance values

[kcawley]

This is additional text to clarify which pH and specific conductance values that users should prioritize using.

[cklunch]

@kcawley Thanks! I think it would be helpful to add a sentence at the start of the new text:

"A few measurements in this data product are also available via the in-stream sensors, most notably specific conductance and pH. Given the potential for additional uncertainty arising from sample collection/processing, shipping, and storage time prior to analysis, we strongly recommend using the in-situ Water quality (DP1.20288.001) sensor data whenever possible, particularly for specificConductance and pH. Alternatively..."

Otherwise it sounds a little bit like we're recommending no one use the water chemistry data product at all.

And I'm wondering if it would be good to use different language in the groundwater chemistry QSG - does the water quality data really reflect what's happening in the groundwater? Or is there a groundwater sensor we can point them to?

[cklunch]

@kcawley Checking in on this stale PR - any thoughts? Thanks!