The water budget was reconstructed for the period of discharge record for the Ipswich River watershed, Massachusetts.  Methods are summarized in Claessens et al. 2006.  Data through 1999 are from Claessens et al. 2006.  Data for 2000 through 2008 are updated using precipitation collected at the PIE LTER rain gage in Byfield, Newbury MA, and water withdrawal summarized in Wollheim et al. 2013. From 2008 to 2014, we have updated precipitation and stream flow only, because of difficulties in gainging water withdrawal data. 

Briefly, precipitation for 1931-2000 was estimated from interpolated  precipitation gages in and surrounding the Ipswich and Parker River watersheds, while for 2001 through 2018 precipiation was updated using precipiation amounts from the PIE LTER rain gage (see PIE LTER Climate data).  Discharge was calculated from USGS gage data at the Ipswich gage at Ipswich (#01102000).  Water supply source, public water export, and amount of sewage exported are based on town level tabular information compiled over time for towns within the basin.  All sewage water is exported from the basin, as there are no sewage treatment plants in the basin.  ET was calculated by difference (PPT-RO-netExport).  For more details see Claessens et al. 2006

All variables were standardized as depth of water per year (mm/yr) to construct the budget, using the area of the Ipswich River watershed (404 km2).  That is, total volume of water per time was divided by watershed area and converted to mm/yr.

Claessens, L., C. Hopkinson, E. Rastetter, and J. Vallino. 2006. Effect of historical changes in land use and climate on the water budget of an urbanizing watershed. Water Resources Research 42:W03426.

Wollheim, W.M, M.B. Green, C.S. Hopkinson, B.A. Pellerin, N.B. Morse. 2013. Impacts of ecosystem service regionalization on a suburban New England watershed.  Estuaries and Coasts. DOI 10.1007/s12237-013-9646-8