Dutch Hollow Brook Streambank Protection
Cayuga County, NY

Grantee: Cayuga County Water Quality Management Agency
Basin Program Funds: $10,000
Non-federal Funds: $8,700
Project Duration: 09/1994 - 08/1995
Status: complete

Problem Statement
Dutch Hollow Brook has been identified as one of three major contributors of significant amounts of sediment, nutrient, and pesticide loading into Owasco Lake. Sediment deposits result in turbidity problems for the water supply and excessive weed growth. In addition, sedimentation from bank erosion has clogged the stream's channel resulting in winter ice jamming and flooding.

Background
The Dutch Hollow Brook Streambank Protection project seeks to improve and protect the quality of Owasco Lake, a major source of drinking water in Cayuga County, by controlling nonpoint source pollution originating from Dutch Hollow Brook, a tributary to the lake.

A 1974 study by the Soil Conservation Service shows that Dutch Hollow Brook's 131 miles contributes 64.6 tons of soil per bank mile per year. Bank heights range from two feet to 300 feet high with a 5:1 feet slope, and is less than 3/4 miles from the mouth of Owasco Lake. Past studies have indicated that 60% of sediments entering the lake come from within the first mile of its inlet.

Activities
After a number of meetings with the property owner of the project site, the site was surveyed and a design was drawn up that would best solve the erosion problems. The following Best Management Practices (BMPs) were then implemented.

• 180 feet of rip rap was placed along the streambank and heavy debris was removed at the base of the bank
  
  
• A small retention pond was dug at the base of the bank for sediment storage and control
  
  
• Underground drainage tiles were laid to divert groundwater
  
  
• The steep bank was terraced, seeded, and mulched in the fall of 1994 and the summer of 1995

By removing the south gravel bar, heavy debris at the foot of the bank, and dredging the channel to a depth of 14 feet. The stream channel capacity was increased by 50%. The slope of the bank was reduced to 3:1 feet by forming two terraces. Flood prevention benefits were observed during the spring of 1995 along with reduced soil erosion.

Results
The quantity of soil saved has been approximately six tons per 180 feet. This is due to the former steepness of the bank and the use of the retention pond. With the reduction of soil loss, 198 pounds of potassium, 26.4 pounds of phosphorous and 39.6 pounds of nitrogen were saved.

Future dredging of the pond will have to be done as needed and the bank will be monitored for any future maintenance or reseeding needs.

Contact: Cayuga County Water Quality Management Agency, (315) 252-4171