8.0.3 Totals and Average Loading by Watershed

Totals

Totals are approximated by averaging all the values. Data that is missing is not included. Storm events are included.

Flow

The Pelican River inlet accounts for nearly three quarters of the water entering Pelican Lake via streams at an approximate average of 70 cfs, or 44 million gallons per day. Duck Lake is nearly insignificant at 0.56 cfs or 360 thousand gallons per day.

Phosphorous

In comparing the total phosphorus between the different inlets, the Pelican River accounts for over half (62%) of the total phosphorus entering Pelican Lake (see figure below). This would prioritize this stream for source identification; however, the phosphorus concentration in the Pelican River is average compared to the other sites, and is nearly half of other area streams. This would suggest that heavy loading is due to the shear volume of water (see figure above).

The figure below shows the actual phosphorus loading for each inlet. Duck Lake is a small inlet that trickles in from a wetland on the west side of Pelican Lake. The flow and phosphorus loading from Duck Lake is negligible.

In looking at all the monitoring sites in each watershed, one can better pinpoint potential sources of phosphorus (see figure below). In the Bob Creek watershed, both the Burton Lake Outlet (upstream) and the Bob Creek Inlet to Pelican Lake have similar phosphorus loading. This result means that not much phosphorus is picked by Bob Creek as it passes through a cattle farm and a large wetland.

In the Spring Creek Watershed, water exits Lake Ida and Big Cormorant Lake with very low phosphorus concentrations. The Sherbrooke Road site has higher phosphorus loading than the source at Big Cormorant Lake as Spring Creek winds back and forth through the city of Cormorant , numerous wetlands and picks up phosphorus as it flows. Further downstream, the branch from Lake Ida joins Spring Creek and then enters Pelican Lake at the Spring Creek Inlet. The phosphorus loading at the Spring Creek Inlet is slightly higher than at Sherbrooke Road , which could come from the Lake Ida branch or the wetlands.

The Pelican River has the highest phosphorus loading of all the watersheds. The Highway 20 site is just upstream from Little Pelican Lake and the Stroms Bridge site is between Little Pelican and Pelican Lakes . The results show that some phosphorus remains in Little Pelican Lake and most likely gets taken up by plants and algae for food.

The sum of the phosphorus loading from the inlets is higher than from the Pelican River Outlet, but this is common in lakes. The extra phosphorus gets utilized by plants and algae in the lake and also gets deposited at the bottom of the lake into the sediments.

Chlorophyll A

The chlorophyll a (algae concentration) loading patterns in Pelican Lake follow the phosphorus loading patterns since phosphorus is food for algae (Figure 2.19-2.20).

Total Suspended Solids

Total Suspended Solids (TSS) averages around 1 to 3 mg/L per site and is evidence to the clarity of the Areas Rivers and streams. In comparing inlets, they follow the same pattern in loading as for flow and phosphorus. The Pelican River is the largest contributor of TSS to Pelican lake, but this is due to the shear volume of water flowing in from that inlet.

Next page: Inlets and Outlet loading comparisons