CAZENOVIA — On July 28, the Cazenovia Lake Association (CLA) and the Cazenovia Preservation Foundation coordinated a cleanup of a section of Chittenango Creek between the two dams downstream of the lake outlet.

The lake dam, or upper dam, which controls the level of the lake, is located near Carpenter’s Pond. Mill Street dam (lower dam or creek dam), which was built to serve the Erie Canal system, is a little further downstream.

Just east (downstream) of the lake dam, Chittenango Creek meets the water flowing out of the lake to form a single channel.

According to Lauren Lines, executive director of the Cazenovia Community Development Association (CACDA), Mill Street dam was built in 1857 to control water flow upstream of the confluence of Chittenango Creek and the Old Erie Canal.

Before the dam went up, the water in the area between the two dams was low, fast moving, rocky, and generally looked much like any other natural section of Chittenango Creek today.

“This process significantly changed the ecosystem of this 1,000-foot section of the stream,” said Lines.

Since the dam’s construction, the water level between the two dams has been artificially regulated by either raising or lowering Mill Street dam’s sluice gates.

Typically, the New York State Canal Corporation, which owns and operates both dams, leaves the sluice gates fully open from Nov. 1 through April 1. Therefore, the water level between the dams is always low during the winter.

Mill Street dam issues

Recently, CLA and CPF have been working with a team of partners to investigate and address ongoing issues related to Mill Street dam.

The collaborators include the Village of Cazenovia, the Town of Cazenovia, the New York State Canal Corporation, the New York State Department of Environmental Conservation (DEC), the United States Fish and Wildlife Service, CACDA, Trout Unlimited, and Jocelyn Gavitt, who is consulting through Gavitt Associates, a firm specializing in landscape architecture and community design.

When the water level between the dams is high, any significant precipitation can cause the water to flow the wrong way; instead of moving downstream, it backflows over the lake dam and into the lake, carrying with it significant amounts of sediment and pollutants.

According to Lake Health Committee Member Bob Crichton, who has helped study the backflow issue, such events are detrimental to the lake in multiple ways.

Crichton explained that as part of its five-year plan, the CLA has been studying the overall water quality of the lake. One focus of that research has been the runoff that flows into the six largest streams that feed into Cazenovia Lake.

CLA used a three-year study from Cazenovia College, which measured phosphorus levels from all inflow sources to the lake, as the basis for determining the six largest inflow streams.

For the past three years, CLA has collected water samples from these six streams in early spring and again following a major rainfall event in the summer. The samples, which are sent to Upstate Freshwater Institute (UFI) for analysis, are measured not only for phosphorus, but also for nitrogen, ammonia, chlorides, suspended solids, specific conductance, and total dissolved phosphorus.

The backflow problem, Crichton recalled, was identified after a major rainfall in 2020 and again in 2021.

“We collected samples at the upper dam and at the end of the canal at the lakeside as we did with the stream studies,” he said. “The backflow lab results from the UFI were stunning, as they showed phosphorus levels running into the lake that were 1.8 to 6.6 times higher than any of the six streams we tested, and total suspended solids levels that were 5.5 to 11.4 times higher than the streams.”

Cazenovia Lake was recently added to a DEC 303(d) “Impaired Water Body Listing” due to elevated phosphorous levels.

Crichton explained that high phosphorus levels promote algae growth and increased vegetation, which is why working to maintain the natural phosphorus to nitrogen balance of a healthy lake is so important.

“Cazenovia Lake has experienced algal blooms every year since 2013 — both toxic and non-toxic forms,” he said. “There is an increased density of blooms near the outlet of the lake over this time period.”

Crichton also noted that the introduction of suspended solids during backflow events leads to increased sediment in the southeast end of the lake.

The CLA’s sediment depth measurements show an average of 12 inches of sediment at the lake outlet compared to an average of less than 3 inches at various other points along the east shore of the lake.

“Increased sediment decreases the depth of the lake and could eventually make boat travel in these [areas] impossible,” said Crichton. “The sediment is nutrient-rich and leads to greater weed growth in these areas as well.”

Additional issues related to Mill Street dam arise during very dry seasons, like this summer, when the water level between the dams is low.

For example, such conditions can lead to higher levels of fish mortality, make it impossible to kayak or canoe in that 1,000-foot stretch of water, and leave the banks looking like a muddy mess.

Stream restoration

As a long-term solution to the problems at hand, CLA, CPF and their partners aim to restore the stream between the dams to its natural, pre-Erie Canal state and appearance.

“There is no longer any operational need for the Mill Street dam, and the goal of the program is to restore the creek to its natural state,” said Lines.

According to Miller, apart from solving the backflow problem and eliminating the excess pollution it brings into the lake, a stream restoration would provide for a better fish and wildlife habitat, would significantly reduce the possibility of fish dying during low water conditions, and would improve the ascetics of the stream.

“Currently, trout cannot get farther upstream because of the Mill Street dam,” Miller said. “A stream restoration will involve putting in rock veins across the stream, which will provide for spawning and living pools for the trout. Additionally, the restoration will include bank stabilization with proper plantings to reduce sediment flow downstream.”

Miller highlighted several successful stream restoration projects completed on Chittenango Creek.

An overview of these projects is provided in the April 2018 issue of New York State Conservationist (dec.ny.gov/docs/administration_pdf/0418consmag4web.pdf).

Short-term solution

As a shorter-term solution to Mill Street dam issues, the Canal Corporation has decided to leave the sluice gates open this summer to allow for rapid drainage in a storm event. The Canal Corporation also added “stopper logs” in front of the dam in the beginning of June to retain a base level of water between the dams but also allow any excess water to pour directly over the top of the logs.

“This has been effective at keeping the water approximately 12 inches higher than it was before the stopper logs were installed between the two dams,” said Miller. “It is also logical that it would help reduce backflow; however, we have not had enough rain this summer to verify if it would eliminate backflow. But it seems to be an adequate intermediate solution while the stream restoration and dam removal projects are being planned out.”

Planning for partial/complete dam removal

Recently, CLA contracted with Ramboll engineering company to conduct a limited feasibility study regarding some longer-term options for Mill Street dam.

On July 27, Miller reported that the draft study, which was expected to be completed that week, is primarily focused on examining partial and full removal of Mill Street dam and determining whether there would be any flooding impacts downstream.

Ramboll is also tasked with determining if the dam removal will solve the backflow problem and investigating potential modifications to the “T” where Chittenango Creek intersects the water flowing out of the lake between the two dams.

As of July 28, CACDA was in the process of applying (on behalf of the village) for a Local Waterfront Revitalization Program (LWRP) grant for further study of Mill Street dam.

“The grant would fund additional investigation, preliminary design and initial permitting for partial removal of the Mill Street dam and subsequent stream restoration between the two dams,” said Lines. “Once that is complete, we will be in a position to apply for final design and construction. We will not find out if this initial request is funded until December of this year.”

Creek cleanup and other CPF initiatives

During the July 28 creek cleanup, CLA and CPF volunteers took advantage of the low water levels to remove some of the trash and debris that, until recently, had been submerged.

“A lot of the trash and debris that gets picked up during a big storm event ends up here in this section of the creek where the water slows down upstream of the dam,” said CPF Executive Director Jen Wong.

CPF presented the cleanup as an installment of its “Trail Work Thursdays.”

On the last Thursday of each month from June through October, weather permitting, CPF board members, staff, and other volunteers meet up to spend an hour or two beautifying the community trails before grabbing refreshments at a local establishment.

“We want to thank the members of the CLA who came out to join us for this Trail Work Thursday,” said Dave Gerber, CPF stewardship committee co-chair. “We really appreciate the volunteers that help us on these workdays and throughout the year. We’d also like to thank the village for hauling away debris, both for this workday, as well as various other clean-up events and workdays throughout the year.”

Wong stated that while CLA takes the lead with respect to protecting the lake, CPF maintains close correspondence with the lake association and actively follows its current management activities and proposed longer-term solutions for this area of the creek.

“Many community residents know that the Willow Patch, which is adjacent to this section of creek, is a CPF property,” said Wong. “This section of the dike trail is very popular, with some people walking it on a daily basis, so naturally, CPF has received quite a few inquiries this summer about the water levels.”

Wong also reported that the Canal Corporation has completed its gatehouse renovation at the lake dam and will be returning to restore the trail surface later this summer. Additionally, she noted that the 136 trees, shrubs and herbaceous plants planted in the Willow Patch this spring are doing well despite the hot, dry summer.

“With the exception of a couple of hybrids selected for their ability to grow in areas with particularly poor soil and lots of rubble, the plants selected were primarily native species that will naturalize and help diversify the plantings in the Willow Patch, which are primarily non-native willow,” she said.

CPF is a private, non-profit organization that works to protect the historical, agricultural, and natural resources in and around Cazenovia for the benefit of the community and the enjoyment of future generations. For more information and upcoming events, visit cazpreservation.org.

CLA is an all-volunteer organization consisting of residents, homeowners, business owners, and elected officials who strive to protect the environmental and recreational sustainability of Cazenovia Lake. Learn more at cazlake.org.