1. Watershed Origins of Sediment Loads
Sediment Loading from Three Tributary Streams to the South End of Cayuga Lake,
Watershed Origins of Sediment Loads
WRC-Cornell Partnership Meeting
November 25, 2014

2. Selected USGS LOADEST Regression Model 3 Based on Statistical Criteria (Bias < 25%; Nash Sutcliffe Efficiency Index)

3. Comparison of CSI and USGS Sediment Load Estimates at German Cross Road, tons/year x 103
‘04
‘05
‘06
‘07
‘08
‘09
‘10
‘11
‘12
Mean
CSI
12.8
21.5
16.4
10.4
6.9
2.8
8.1
40.1
3.7
13.6
+/- 11.6
USGS
22.5
15.9
49.9
21.3
10.3
7.6
14.8
51.9
5.1
22.1
+/-17.3
Ratio
CSI/
0.57
1.4
0.33
0.49
0.67
0.37
0.54
0.77
0.73
0.65 +/- 0.32

4. CSI-USGS Differences: Sampling, Measurement, and LOADEST Calibration
CSI volunteers collect grab samples; USGS uses submerged autosampler
CSI measures Total Suspended Solids (EPA method); USGS measures total sediment (USGS method)
CSI calibrates LOADEST by pooling concentration-flow data from all years to obtain a single calibration curve; USGS re-calibrates LOADEST each year
Results show that CSI protocol “low balls” sediment loading estimates at German Cross Road by about 1/3, on average, compared to USGS

5. Downstream Increases in Fall Creek Sediment Loads, tons/year
2009
2010
2011
2012
2013
Davis Rd
647
595
1,528
393
653
Freeville
1,277
1,114
3,299
811
1,436
Freese Rd
7,412
7,594
30,038
3,415
10,512
Cayuga St.
10,396
9,754
34,257
5,225
12,475

6. Stormwater Impacts on Fall Creek Sediment Yields, tons/year/mile2
% Load in Storm
Yield, 2012
Davis Rd
41.9
73%
10.8
54%
Freeville
50.5
78%
12.4
58%
Freese Rd
240.3
89%
27.3
69%
Cayuga St.
269.7
86%
41.1
65%

7. Summary: Sediment Loading from Fall Creek to Cayuga Lake
Upper Fall Creek watershed above Freeville accounts for ~11% of sediment loading to Cayuga Lake
Lower Fall Creek watershed accounts for ~70% of sediment load, Virgil Creek for ~19%
Increased stormwater flows in 2011, including Tropical Storm Lee, resulted in a ~6x increase in sediment yields from the Fall Creek watershed, ~4x in the upper watershed, when compared to 2012, a low flow year

8. Downstream Increases in Six Mile Creek Sediment Loads, tons/year
2009
2010
2011
2012
2013
600 Rd
203
444
1,799
200
228
German Cross Rd
2,775
8,110
40,096
3,732
5,346
Plain St.
2,499
7,018
36,130
3,850
5,631

9. Stormwater Impacts on Six Mile Creek Sediment Yields, tons/year/mile2
% Load in Storm
Yield, 2012
600 Rd
149.9
93%
16.7
81%
German Cross Rd
1,038.7
95%
96.7
84%
Plain St.
734.4
94%
78.3
82%

10. Summary: Sediment Loading from Six Mile Creek to Cayuga Lake
Stormwater typically accounts for ~82% of total sediment load in Six Mile Creek compared to ~65% in Fall-Virgil Creek, consistent with its “flashiness”
Extreme stormwater flows in 2011, particularly Tropical Storm Lee, resulted in a ~9x increase in sediment yields from the Six Mile Creek watershed compared to 2012, a low flow year

11. Downstream Increases in Cayuga Inlet Sediment Loads, tons/year
2009
2010
2011
2012
2013
Blakeslee Rd
517
1,745
33,537
678
1,237
Upstream of Buttermilk
3,736
5,187
37,845
1,977
1,625
Cherry & Tabor St. ND
52,959
2,333
2,920
Farmers Mkt.
70,312
2,942
4,325
Cass Park
72,355
2,933
3,845

12. Stormwater Impacts on Cayuga Inlet Sediment Yields, tons/year/mile2
Yield, 2011 tons/year/mile2
% Load in Storm
Yield, 2012 tons/year/mile2
Blakeslee Rd
989.3
98%
20.0
78%
Upstream of Buttermilk
536.1
94%
28.0
67%
Cherry and Tabor St.
583.3
96%
25.7
57%
Farmers Mkt.
491.7
20.6
62%
Cass Park
457.9
97%
18.6
58%

13. Summary: Sediment Loading from Cayuga Inlet to Cayuga Lake
The upper Inlet above Blakeslee Road contributes about ¼ to 1/2 half of the total Inlet sediment load to Cayuga Lake, depending on stormwater flows
Extreme flows in 2011, including Tropical Storm Lee, resulted in a ~25x increase in the yield of sediment from the Inlet compared to 2012
Sediment loads at Cass Park were less than the combined loads from Six Mile Creek at Plain Street plus the Inlet at Cherry & Tabor Streets, indicating sediment is trapped in the lower Inlet

14. Sediment Trapping in the Lower Cayuga Inlet, tons/year
2011
2012
2013
Sum of loads at (Cherry & Tabor St.) + (Plain St.)
89,089
6,183
8,550
Load at (Cass Park) – (Cascadilla Creek)
67,260
2,115
3,027
Difference = Sediment Trapped in Lower Inlet
21,829
4,068
5,523

15. Sediment Trapping in the Lower Cayuga Inlet
Between 2011 to 2013, approximately 31,420 tons of sediment were trapped in the lower Cayuga Inlet from Cherry & Tabor St. to Cass Park, about 2/3 due to Tropical Storm Lee in 2011
In years of normal flows, such as 2012 and 2013, about 2/3 of sediment from the Inlet and Six Mile Creek is trapped in the lower Inlet and about 1/3 enters Cayuga Lake
Extremely high flows in 2011 pushed most of the sediment into the lake, however, ~4x more was trapped in 2011 than either 2012 or 2013

16. Practical Applications of Sediment Loading Estimates Acquired Through Volunteer-CSI Monitoring Partnerships
Track build-up of sediment in lower Inlet
Track build-up of sediment in City of Ithaca drinking water reservoir
Identify upstream areas in Cayuga Inlet watershed that are prone to extreme sediment loss during “100-year” floods
Estimate rate at which southern shelf of Cayuga Lake is filling in with sediment