Streambank Inventory

Methodology

There are 140 tributaries in the Cayuga Lake Watershed. Data was taken from 1100 sites in the watershed. A visual survey was performed at several sites on each tributary to obtain the information needed to rank the erosion potential of each subwatershed and direct drainage. The information gathered is was fed into the stream factor equation in order to obtain a relative stream factor number. The higher the stream factor the greater the potential erosion problem. All subwatersheds and direct drainage areas were then ranked according to their erosion potential. The stream rankings for the Cayuga Lake Watershed ranged from 50 to 1350. For the purposes of analysis the following erosion classifications were developed based on the average of all stream ranks within a given subwatershed:

Minor - stream rank mean of 50-80

Appreciable - stream rank mean of 81-125

Severe - stream rank greater than 125

Low end of severe - stream rank of 125-250

Moderately severe - stream rank of 251-350

Very severe - stream rank of 351-1350

Site locations where digitzed into a geographical information system. The collected data was then joined to the site locations for the purposed of mapping and analysis.

Stream Factor Equation = (Bottom material value + side slope condition value + vegetative condition value) + ((average velocity) X number of tributary miles in the watershed)

Stream Factor Variables:

Bottom Material: soil, gravel, or bedrock

Side Slope Condition: not eroded, partially eroded, or severely eroded

Vegetative Condition: heavily vegetated, sparsely vegetated, or no vegetation

Average Velocity: depth, bottom material, obstructions, meander, surface irregularities, vegetative cover, and channel size

Mannings Equation V = 1.49 r 2/3 s 1/2 / n

r = hydraulic radius

s = slope

n = basic roughness coefficient + modifying value for surface irregularity + modifying value for variations of cross sections + modifying value for obstructions + modifying value for vegetation + modifying value for meander

Tributary Miles: total length of longest branch of the tributary or average length of sampled tributaries for the direct drainage areas.

Analysis

The streambank data collected from the Cayuga Lake watershed displays various trends regarding erosion and sedimentation ultimately affecting water quality in the lake. Minor erosion is occurring along the western and eastern subwatersheds north of the Taughannock Creek subwatershed and the Salmon Creek subwatershed. The direct drainage basins on the southern end of the lake appear to pose little problems in regards to erosion. More appreciable erosion is apparent in the northeastern subwatersheds in Yawger Creek, Great Gully and Lavanna Area subwatersheds. Taughannock, Bolter, and Spring Brook subwatersheds also show a trend of appreciable erosion. The Salmon Creek major subwatershed (Salmon, Little Salmon, and Big Salmon Creeks) is on the low end of severe with stream ranks between 125-250. The large subwatersheds on the southern end of the lake with the exception of the direct drainage basins are responsible for appreciable loads of sediment flowing into the lake. Fall, Virgil, and Sixmile Creeks are all categorized as moderately severe with a few very severe sites. The Cayuga Inlet is characterized as very severe and contains some of the highest stream ranks in the watershed. Map 3.4.2 shows the Streambank Inventory sites and classifications. Map 3.4.3 shows the erosion classification by subwatershed. The following is a brief description of streambank erosion in the subwatersheds of the Cayuga Lake Watershed:

Barnum Creek

Sites Sampled: 4

Stream Rank

High: 89.1

Low: 43.3

Average: 64.9

Comments: No significant sites

Big Hollow Area

Sites Sampled: 8

Stream Rank

High: 83

Low: 42.3

Average: 65.7

Comments: No significant sites

Big Salmon Creek

Sites Sampled: 48

Stream Rank

High: 712

Low: 87

Average: 189.5

Comments: There are some exceptions on some of the small tributaries flowing into the major stream, but for the most part the streambank erosion is relatively severe.

Bloomer/Mack Creeks Area

Sites Sampled: 11

Stream Rank

High: 89.1

Low: 38.5

Average: 58.2

Comments: No significant sites

Boardman Creek

Sites Sampled: 12

Stream Rank

High: 99

Low: 50.5

Average: 75

Comments: This subwatershed appears to have a few significant sites. Three sites had stream ranks in the appreciable category but none exceeded 100.

Bolter Creek

Sites Sampled: 19

Stream Rank

High: 151.9

Low: 55.5

Average: 101.3

Comments: Along the main stem of Bolter Creek a few sites were identified as problematic contributing to sedimentation in Cayuga Lake. The small tributaries feeding the main stream appear to be in good shape, but once they flow into Bolter Creek the condition of the streambanks decreases.

Buttermilk Creek Area

Sites Sampled: 28

Stream Rank

High: 233.4

Low: 59.5

Average: 119.5

Comments: Upstream, the tributaries tend to be in good shape with a few exceptions. However, when they flow into the main creek the condition of the streambanks becomes degraded.

Canoga Creek Area

Sites Sampled: 4

Stream Rank

High: 78.8

Low: 51.3

Average: 65

Comments: No significant sites

Cascadilla Creek

Sites Sampled: 20

Stream Rank

High: 174

Low: 63.3

Average: 111.5

Comments: Most of the stream ranks were over 100 with a few exceptions at the headwaters of various tributaries.

Cayuga Inlet

Sites Sampled: 78

Stream Rank

High: 1315.5

Low: 99.5

Average: 362

Comments: This subwatershed has the highest rank and therefore appears to need the most attention. No site sampled could be classified as minor.

Cayuga View Area

Sites Sampled: 5

Stream Rank

High: 176.6

Low: 97.3

Average: 130.8

Comments: This area is classified as severe. This may be caused by the steep gradients in the area.

Cayuga Village Area

Sites Sampled: 2

Stream Rank

High: 138.3

Low: 88.1

Average: 113.2

Comments: With only two sites sampled, it is hard to have an accurate account of the streambank erosion in this area. However, one of the sites sampled showed signs of severe streambank erosion.

Enfield Creek

Sites Sampled: 38

Stream Rank

High: 260.3

Low: 72

Average: 131.4

Comments: The average was just high enough to classify the area as severe. There were some exceptions with tributaries that weren’t as severely eroded, but most of the sites showed signs of severe streambank erosion.

Fall Creek

Sites Sampled: 84

Stream Rank

High: 762.7

Low: 101.8

Average: 234.8

Comments: This area is classified as severe, and not a single site sampled had a ranking of below 100. There appears to be major sediment loading to the lake from this subwatershed.

Fish Kill

Sites Sampled: 20

Stream Rank

High: 193.6

Low: 53.5

Average: 97.4

Comments: As a whole, the erosion occurring within the subwatershed isn’t severe, but there are a few exceptions in some tributaries that may deserve attention.

Glen/Dean Creeks Area

Sites Sampled: 12

Stream Rank

High: 96

Low: 53.5

Average: 70.7

Comments: There wasn’t much erosion evident, but there were a couple of sites that could be classified as appreciable.

Glenwood Creek

Sites Sampled: 20

Stream Rank

High: 87.5

Low: 35.25

Average: 60.37

Comments: No a significant sites

Great Gully

Sites Sampled: 23

Stream Rank

High: 192.8

Low: 77.3

Average: 112.1

Comments: Classified as appreciable, but certain tributaries in this subwatershed need more attention then others. Erosion increases after the tributaries join the main branch.

Groves/Powell Creeks Area

Sites Sampled: 13

Stream Rank

High: 92.5

Low: 44.8

Average: 65.5

Comments: No significant sites

Gulf Creek Area

Sites Sampled: 11

Stream Rank

High: 78

Low: 54

Average: 65.3

Comments: No significant sites

Hicks Gully

Sites Sampled: 7

Stream Rank

High: 87.1

Low: 58.9

Average: 70.8

Comments: Few significant sites

Interlaken Area

Sites Sampled: 42

Stream Rank

High: 84

Low: 34

Average: 53.9

Comments: No significant sites

King Ferry Station Area

Sites Sampled: 28

Stream Rank

High: 87.1

Low: 43.8

Average: 63.1

Comments: No significant sites

Lake Ridge Point Area

Sites Sampled: 15

Stream Rank

High: 85.6

Low: 41.1

Average: 65.3

Comments: No significant sites

Lansing Area

Sites Sampled: 16

Stream Rank

High: 84.3

Low: 41.3

Average: 64.9

Comments: No significant sites

Lavanna Area

Sites Sampled: 10

Stream Rank

High: 108.3

Low: 54.4

Average: 85.4

Comments: Some significant sites

Little Creek Area

Sites Sampled: 12

Stream Rank

High: 109.6

Low: 54.2

Average: 79.8

Comments: Some significant sites

Little Salmon Creek

Sites Sampled: 21

Stream Rank

High: 162.3

Low: 63.2

Average: 104.4

Comments: This subwatershed is part of the Salmon Creek major subwatershed, which has some significant streambank erosion problems.

Locke Creek

Sites Sampled: 17

Stream Rank

High: 138.2

Low: 55.7

Average: 86.8

Comments: This subwatershed should be considered an area of concern

McDuffie Town

Sites Sampled: 6

Stream Rank

High: 69.8

Low: 48

Average: 59.6

Comments: No significant sites

Minnegar Creek Area

Sites Sampled: 6

Stream Rank

High: 81.8

Low: 41.3

Average: 67.2

Comments: The erosion problems in this area are minimal.

Paines Creek

Sites Sampled: 31

Stream Rank

High: 225.9

Low: 73.7

Average: 131.9

Comments: Some sites in this area are highly eroded deserving some concern. There are someexceptions at the headwaters of some of the tributaries in this area.

Red Creek

Sites Sampled: 4

Stream Rank

High: 89

Low: 60.2

Average: 73.3

Comments: This is classified as minor.

Salmon Creek

Sites Sampled: 42

Stream Rank

High: 260.9

Low: 74.8

Average: 137.5

Comments: The major tributary in the subwatershed flows directly into the lake and most all of the sites sampled had significant erosion. This area is part of the Salmon Creek major subwatershed and should considered a subwatershed of concern.

Schuyler Creek

Sites Sampled: 10

Stream Rank

High: 67.6

Low: 42.8

Average: 56.8

Comments: Streambank erosion in this subwatershed is minimal.

Sheldrake Creek

Sites Sampled: 15

Stream Rank

High: 99.2

Low: 61.9

Average: 75

Comments: The erosion in this subwatershed is minimal.

Sixmile Creek

Sites Sampled: 55

Stream Rank

High: 375.1

Low: 76.5

Average: 205.5

Comments: Most of the sites sampled showed evidence of significant streambank erosion.

Spring Brook

Sites Sampled: 30

Stream Rank

High: 203.9

Low: 73.4

Average: 129.5

Comments: Most all of the tributaries showed signs of significant erosion with a few exceptions.

Taughannock Creek

Sites Sampled: 51

Stream Rank

High: 385.4

Low: 82.8

Average: 168.2

Comments: The erosion along the streambanks in this area is classified as severe. There were some exceptions along some of the small tributaries flowing into the main stem of Taughannock Creek, but the main stem didn’t have a single ranking below 150.

Trumansburg Creek

Sites Sampled: 5

Stream Rank

High: 83.1

Low: 45.8

Average: 58.5

Comments: The streambank erosion in this area is minimal.

Union Springs Area

Sites Sampled: 23

Stream Rank

High: 118.4

Low: 53.7

Average: 79.6

Comments: Most of the tributaries are in fairly good shape, but there are some exceptions. A couple small tributaries, which flow directly into the lake, have stream ranks above 100.

Virgil Creek

Sites Sampled: 42

Stream Rank

High: 386.8

Low: 84.7

Average: 188.4

Comments: This ranking classifies the area’s streambank erosion as severe. There are many sites with stream ranks greater than 150.

West Branch

Sites Sampled: 18

Stream Rank

High: 314.4

Low: 61.9

Average: 136.5

Comments: Many of the tributaries sampled near the headwaters were in fairly good shape, but as the sites got nearer to the mouth, the streambank erosion appeared significantly worse.

Willow Creek Area

Sites Sampled: 24

Stream Rank

High: 92.7

Low: 42.6

Average: 58.2

Comments: Streambank erosion in this area is minimal.

Yawger Creek

Sites Sampled: 39

Stream Rank

High: 244.2

Low: 70

Average: 123.5

Comments: Streambank erosion is classified as severe. There are a few exceptions with various tributaries, but most of the area has significant streambank erosion occurring.

Map of Streambank Inventory Ranking by Subwatershed

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CLW IO 2004