Posted on October 15, 2026
By Jaime Cone Hughes
Ithaca’s waterfront could begin to look like a working construction corridor in the coming year as pumps, equipment and crews occupy temporary staging areas near Six Mile Creek, the boat houses and Cass Park. Sediment pulled from the waterway will travel as slurry through pipes to an upland containment site near Fairgrounds Memorial Parkway.
The work is designed to solve a problem that has accumulated gradually since the 1960s: sediment has filled portions of the engineered flood-control channel that carries water through the city and connects it with Cayuga Lake.
Officials at the New York State Department of Environmental Conservation (DEC) said they expect dredging to begin in 2027. The agency said it is working with the state Office of General Services (OGS) to establish a bid-advertisement timeline and directed questions about the request for proposals to OGS.
DEC issued a Freshwater Wetlands and Water Quality Certification permit for the project on July 23. The permit authorizes hydraulic dredging in Cayuga Inlet and Old Cayuga Inlet, piping the dredged sediment to an existing Sediment Management Facility for dewatering and storage and releasing filtered water through an adjacent stormwater swale.
DEC is both the applicant and the project sponsor. The agency’s Bureau of Flood Protection and Dam Safety is coordinating with the New York State Canal Corp., the city and town of Ithaca, the U.S. Army Corps of Engineers and other agencies.
“The purpose of the Cayuga Inlet Dredging Project is to restore flood conveyance and water depths for navigation in the Flood Risk Management Channel,” the DEC recently told Tompkins Weekly.
The project will reshape a highly public part of Ithaca for months. It also presents a delicate environmental task in a lake system already affected by sediment, phosphorus, aquatic weeds and invasive Hydrilla.
Dredging plan centers on flood protection in Ithaca
The Flood Risk Management Channel was designed and built by the Army Corps in the 1960s, after Ithaca had experienced repeated flooding. Since then, sediment carried from the surrounding watershed and upland areas has settled in the channel, reducing the depth available for both floodwaters and boats.
The channel now needs maintenance at a scale Ithaca has not seen in years.
The final design calls for removing 180,374 cubic yards of sediment in the planned dredge area, or up to 206,043 cubic yards when the permitted 6-inch overdepth is included. In some locations, dredging could lower the existing mudline by as much as 11 feet.
The dredging footprint covers about 31.6 acres of river bottom along roughly 1.9 miles of Cayuga Inlet and Old Cayuga Inlet. The wider project area extends about 2.8 miles and includes the pipeline route, staging areas and sediment-management facility.
The work will reach north toward the mouth of the inlet, between the Allan H. Treman Lighthouse and Allan H. Treman State Marine Park, and south through the inlet system toward the sediment facility.
The proposal grew out of findings by the Army Corps, which recommended in 2011 that roughly 6 feet of accumulated material be removed from the flood-control channel. The permit application says later hydraulic modeling supported that need, including concerns about flooding that can be worsened by winter ice jams.
“Restoration of the flood and navigation channels in Cayuga Inlet is necessary to reduce flood risks in Ithaca and improve impaired navigation,” according to DEC.
The work is structured around two primary goals. DEC proposed approximately 100,000 cubic yards of dredging targeted to areas with the greatest flood-control benefit. The Canal Corp. agreed to provide matching support for another approximately 100,000 cubic yards, aimed at restoring navigable depth in shallow portions of the inlet.
The dredging is intended to bring the channel back to a “minimally acceptable” condition under Army Corps standards, according to the application.
For residents who remember previous plans involving far larger numbers, the scope has been reduced. Earlier concepts considered dredging roughly 600,000 cubic yards. The current effort is constrained in part by the capacity of the 9.5-acre sediment-management facility, which was built to hold about 200,000 cubic yards.
Funding remains undisclosed before the state awards a contract
DEC would not provide a current total estimated cost or construction funding figure, saying that such information cannot be disclosed until the project is awarded.
But public records show a long and evolving history of state support for the project.
At a March 2023 Tompkins County flood-risk meeting, DEC said it had $5.8 million available for the first dredging phase and estimated it needed another $12 million to maximize the amount dredged using the sediment facility’s capacity. That amounted to an implied funding need of about $17.8 million for that phase, not necessarily a final or current project price.
The state’s 2025 permit package says that the dredging is funded by DEC and the Canal Corp. The application does not provide current dollar figures for either agency’s share.
The sediment facility itself was a separate major investment. The Dormitory Authority of the State of New York awarded a $3.765 million construction contract for the facility in 2019. That expense covered the containment site, not the coming dredging operation.
A 2015 Hydrilla management plan cited $13 million in state funding made available for dredging-related efforts. A separate state capital-assistance record identifies a $2 million appropriation for the city’s inlet dredging project in 2008. Neither figure should be treated as an additional current project cost, because the records reflect different points in a project history spanning nearly two decades.
Boaters, rowers and park users will see temporary disruptions
The DEC said it has coordinated with rowing and recreational boating communities to reduce disruption. Navigation to and from Cayuga Lake is expected to remain open, and nonmotorized boats are expected to retain access to the length of the flood-control channel and the lower reaches of Six Mile, Cascadilla and Fall Creeks.
Still, the waterway will not operate normally. Boats will be excluded from the immediate dredging area and turbidity curtain. The contractor will be required to coordinate in-water activities with local marina traffic. The project documents call for advance notices, navigation aids, scheduling of vessel passage when necessary and efforts to minimize unavoidable blockages.
The inlet is a heavily used corridor for Cornell and Ithaca College rowing programs, recreational rowers, dragon boat teams, anglers, paddlers, boat tours, rental operations and motorized boats. The project application estimates that 657 motorized boat slips serve the inlet corridor during the April-to-October boating season.
Three temporary staging areas will support the work.
The largest, near Six Mile Creek, will cover about 1.479 acres. A boat house’s staging area of about 0.279 acre will require a temporary closure of part of the waterfront walking trail and a pedestrian detour. A 0.810-acre area at Cass Park will occupy a fenced section of turf and trees east of the Cayuga Waterfront Trail, though the application says it represents less than 1% of the park and will not cut off access to the rest of it.
Work is proposed for 7 a.m. to 5 p.m. Monday through Saturday. The application estimated 171 to 274 workdays of actual dredging, depending on production rates.
Hydraulic dredging will send sediment to an upland containment site
The project will use hydraulic dredging.
A dredge will suction fine sediment from the channel bottom and combine it with water into a slurry that is expected to be about 10% solids. The slurry will move through high-density polyethylene pipe to the sediment-management facility.
The method was selected because the material in the inlet is primarily fine-grained sediment, which can be difficult to contain with mechanical dredging equipment. The application says hydraulic dredging is expected to reduce turbidity compared with mechanical removal and allows material to be transferred directly to a confined upland site.
A floating pipeline will be among the project’s most visible features. Depending on the dredge location, the pipe system could run from about 6,210 feet to 14,661 feet, with as much as 11,901 feet floating on the water at one time.
The pipeline will be moved as work progresses and marked with navigation lights where it could affect boat traffic. Up to three booster pumps may be located at staging areas or on a small floating barge.
At the sediment facility, slurry will be placed inside geotextile tubes in a lined, bermed containment area. Water will drain out of the tubes, while the solid material remains.
The filtrate will flow through an existing stormwater swale toward the relief channel. Project documents estimate an average discharge of about 2,355 gallons per minute, with daily volumes ranging from roughly 869,000 gallons to 1.39 million gallons, depending on operating conditions.
The permit requires whole-effluent-toxicity testing because chemical flocculants and coagulants will be used to help separate water from sediment. The testing is intended to determine whether discharge from the dewatering process could harm aquatic life.
If testing or monitoring shows water leaving the facility exceeds permit action levels, the operator must take corrective action and notify DEC within 24 hours. If turbidity or suspended-sediment levels cannot be brought back into compliance, discharge must stop until DEC approves a corrective action.
The project also calls for dredging to pause during significant rainfall, allowing water to be held at the facility until levels decline to avoid worsening flood conditions.
Hydrilla and contaminated sediment create environmental challenges
The southern end of Cayuga Lake is listed by DEC as impaired for silt and sediment, total phosphorus and algal weed growth. Cayuga Lake is also classified as a Class A waterbody, meaning it is used as a drinking-water source.
The permit materials do not conclude that the dredging will make drinking water unsafe. Instead, the environmental assessment predicts temporary and localized water-quality effects if the project’s controls work as designed.
Those controls include turbidity curtains that will surround the active dredging area from the surface to the mudline. The barriers are intended to contain suspended sediment, limit the movement of cloudy water and keep fish out of the immediate work area.
Dredging will unavoidably disturb bottom habitat. The application acknowledges that some bottom-dwelling organisms, fish and fish eggs within the dredge footprint will be destroyed or drawn into the operation.
The project includes a Lake Sturgeon Avoidance Plan that relies on turbidity curtains and scheduling protections near the inlet mouth during periods when juvenile sturgeon are known to gather there. The application concludes the chance of an unlawful take is minimal if the measures are followed.
Sediment contamination is another issue that will require close monitoring
DEC said sediment testing conducted over the past two decades found that the material to be removed is predominantly Class A, a classification for sediment with no appreciable contamination. But three locations in Cayuga Inlet contain historical Class B sediment, indicating slight to moderate chemical contamination, according to DEC.
Historic testing found certain samples with contaminants including mercury, cadmium, copper, lead, PCBs and polycyclic aromatic hydrocarbons. Most of the material is not described as contaminated, but the older sampling results mean workers will monitor the identified locations and take remedial action if contamination is encountered.
The project’s contingency plan requires material with unusual discoloration or strong odors to be segregated and tested further.
Hydrilla presents an unusual challenge. The invasive aquatic plant has been present in Cayuga Inlet since 2011, where it can form dense mats, interfere with boating and crowd out native vegetation.
DEC said the dredging design incorporates measures to prevent Hydrilla from spreading, including hydraulic dredging, turbidity curtains, geotextile tubes and screens. A 3-millimeter screen is planned near the filtrate discharge point to keep plant fragments from leaving the facility.
“The tightly woven, UV-protected geotextile will block sunlight, cutting off the food supply to the hydrilla, eradicating it over time,” according to the DEC.
The sediment will remain in geotextile tubes for years because Hydrilla can remain viable for more than four years. The city will own the dewatered material and will be responsible for its eventual disposal or beneficial reuse under a DEC-approved plan. That future handling is outside the current dredging contract.
