*2.2. Lorenz Inequality Analysis*

The extent of temporal inequality in the TN and TP loads observed at each selected monitoring station were determined using Lorenz Curves and corresponding Gini coefficients (*G*). The Lorenz Curves were created by sorting the daily loads in ascending order and graphing the fractions of the cumulative loads as a function of the fractions of cumulative time (Figure 2). Lorenz Curves were generated for each station from 2010 through 2018 given that the TMDL began in 2010 and data are available from the Chesapeake Bay Nontidal Network through 2018. In a few cases, where data were not available from 2010–2012, data were analyzed from 2013 through 2018.

Lorenz Curves plot on or below a line of equality (Figure 2), with the value of *G* quantifying the extent to which the curve plots below the line of equality. *G* was calculated as the ratio of the area between the line of equality and the Lorenz Curve to the entire area under the line of equality (Figure 2). These metrics are commonly used in economics and have more recently been applied to hydrology and water-quality data [11–15]. In the economics scenario, *G* would equal 0 (i.e., perfect equality) if everyone in the population had the same amount of wealth, while *G* would equal 1 (i.e., perfect inequality) if one person in the population had the entirety of the wealth, while everyone else in the population had none. In the water-quality scenarios, *G* = 0 if every moment contributes equally to observed biogeochemical and/or hydrologic responses, whereas *G* = 1 if one moment contributes to the entirety of the observed responses. The appeal of this analysis is its applicability to data over any duration of time or spatial extent in exactly the same mathematical manner.
