Journal of Student Research 2018

77 Urban Photsphorus Runoff and Loading to Half Moon Lake, Wisconsin flow velocity probe and sample strainer were attached to a culvert ring that was slid ~ 4 ft into the culvert so that they were at the culvert bottom (Fig. 4)

Flow velocity and water depth were measured and recorded every 5 mins. Since ranges in flow were not known prior to the study, a Figure 4. Floor jack holding the culvert ring with flow velocity probe and sampling port in place. discrete time interval sampling program was used to characterize storm P concentration. However, mean summer flow for 2012-2017 ranged from 0.090 – 0.021 ft 3 /s (Table 1)

Year

Mean

Maximum

(ft 3 /s)

(m 3 /s)

(ft 3 /s)

(m 3 /s)

1999

0.091 0.0026

1.25 0.0356

2012

0.022 0.0006

0.64 0.0182

2013

0.021 0.0006

6.51 0.1844

2014

0.090 0.0026

1.38 0.0391

2015

0.047 0.0013

0.99 0.0279

2016

0.046 0.0013

0.49 0.0138

2017

0.022 0.0006

0.45 0.0126

Table 1. Summer mean and maximum flow

The 6700 sampler was programed to grab a sample every 15 min when the depth of the water moving by the sensor reached a certain height (usually 0.2 ft) and stop when the water level fell below the threshold. The