## 2 Materials and Methods
### Field Sampling  
Daily rates of stream metabolism were estimated at our 13 study sites from instream dissolved oxygen (DO) measurements collected over a two-week period (10 June to 26 June) in summer of 2014. An early summer sampling period was chosen in order to encompass a time period where plants in both aquatic and terrestrial systems were expected to be actively growing [35]. Concentrations of DO were recorded at 15-minute intervals over the two-week sampling period using a D-Opto logger (Zebra-Tech Ltd). Stream metabolism was estimated for each study reach using the open-system, single station method [36]. In this method a single DO logger is used to measure DO changes over time at a specific point along the study reach. The DO change is assumed to be uniform throughout the upstream reach. Therefore, potential drivers occurring along this reach are presumed to influence metabolism measurements. Probe deployment followed the recommendations of [PERSON] and [PERSON] [36]. Logger malfunction at one site resulted in this site being excluded from analyses leaving 12 sites included in the study. To determine whole stream metabolism of each study site, the nighttime regression method was used to calculate the reaeration coefficient (\(k\)) as recommended by [PERSON] _et al._[37]. This regression was performed using the River Metabolism Estimator v1.2 spreadsheet macro in Microsoft Excel v14.4.6 [38] developed by [PERSON] and [PERSON] [39]. Regressions were considered reliable if the \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Metric Type** & **Metric Name** & **Description** & **Applicable BMPs** \\ \hline \multirow{8}{*}{_BMP Abundance_} & \multirow{4}{*}{Structural BMP(s) per farm} & Ratio of BMP abundance to the number of farms within a catchment & MS, LAR, EC, BMP summary \\ \cline{3-5}  & & Percentage of riparian & \\  & \% Riparian vegetation & vegetation present in a 30 m buffer area around the stream network & \multirow{2}{*}{RBA} \\ \cline{2-5}  & \multirow{2}{*}{Length of LAR} & Length of LAR adjacent to the stream & & \\ \cline{3-5}  & \% River with LAR & Proportion of the stream length with LAR adjacent & & \\ \cline{3-5}  & \% River protected & Proportion of the stream with either LAR and/or riparian vegetation adjacent & & \\ \hline \multirow{8}{*}{_BMP Location_} & Hydrologic distance to stream & Overland distance from BMP to stream channel & MS, LAR, EC, BMP summary \\ \cline{3-5}  & \multirow{2}{*}{Hydroologic distance to sampling point} & Combined overland and instrument distances water must travel from BMP to sampling site & MS, LAR, EC, BMP summary \\ \cline{3-5}  & \multirow{2}{*}{Flow accumulation} & Catchment area that contributed surface runoff to BMP & MS, LAR, EC, BMP summary \\ \cline{3-5}  & \multirow{2}{*}{\% Flow accumulation} & The summed area contributing surface runoff to BMPs divided by the total catchment area & MS, LAR, EC, BMP summary \\ \hline \hline \end{tabular}
\end{table} 
Table 2: BMP metrics and associated descriptions used to quantify abundance and location of agricultural BMPs in small catchments in southern Ontario. calculated \(k\) coefficient was positive, and the value of R\({}^{2}\) was greater than 0.4 [sensu 39]. Abiding to these constraints, the calculation of the \(k\) coefficient for one site was modified due to the occurrence of weak R\({}^{2}\) values in the nighttime regressions throughout the sampling period. As the recorded data appeared reliable, the \(k\) coefficient of this site was determined using the O'Connor-Dobbins empirical equation as recommended by [PERSON] _et al._[37] for streams with relatively low reaeration coefficients (_i.e._, \(<\)50 day\({}^{-1}\)).