Dredging Feasibility Study Discussed

ASHVILLE - Representatives from EcoLogic LLC, a company that offers environmental consulting in aquatic and terrestrial ecology and wetland analysis, think dredging could help to reduce the amount of sediment in Chautauqua Lake.

Thirty-five people showed up to the BOCES in Ashville on Monday to participate in a public information session regarding the feasibility of dredging Chautauqua Lake. Reducing sediment will help reduce vegetation and algae by taking away the nutrients that feed them.

The session, which lasted just over two hours, discussed public opinion of the lake, studies being done on lake sediment and the difference between mechanical and hydraulic dredging, as well as other lakes in the state which have experimented with dredging.

Article Photos

EcoLogic representative Steve Eidt leads discussion on dredging at the BOCES in Ashville.
P-J photo by Remington Whitcomb

Many different topics were discussed, however the specific cost of dredging cannot yet be calculated. As research continues, however, a ballpark number should start to develop.

PUBLIC OPINION OF THE LAKE

Liz Moran and Steve Eidt, both representatives from EcoLogic, led discussions of research regarding public opinion of the lake, as well as the feasibility of different types of dredging.

Moran began by explaining that five areas of the lake, which have been selected through a combination of an online public survey, field assessments and individual interviews, are set to undergo bathymetric mapping on Aug. 6 to better understand the degree of sediment acquired by the lake.

Next, Moran showed the audience a series of graphs which have been calculated through responses of an online poll held at www.ecologicllc.com/chautauqua-implementation.html.

Out of the graphs viewed, some of the most outstanding results were:

With regards to water clarity, 36 percent of participants were dissatisfied with Chautauqua Lake, while 46.5 percent said they were very dissatisfied;

With regards to favorable swimming, 32 percent of participants were dissatisfied with the lake, while 59 percent were very dissatisfied;

With regards to amount of underwater aquatic vegetation, 70 percent of participants were very dissatisfied with the lake;

With regards to navigability of the lake, 33 percent of participants were dissatisfied, while 40 percent were very dissatisfied;

With regards to fishing, 40 percent of participants were neutral about the quality of the lake;

72 percent of participants said sediments affect their ability to use the lake;

87 percent of participants believed sediment in the lake is worse now than it was five years ago.

Moran concluded by stating that understanding the amount of sediment as well as the content of the sediment at all of the bathymetric examination sites will help to contribute to where and how much dredging will take place.

MECHANICAL VERSUS HYDRAULIC DREDGING

When Eidt took the floor, he discussed what types of dredging are best utilized in different scenarios. Eidt mainly spoke about two different types of dredging: mechanical versus hydraulic dredging.

"How many of you remember going to the beach as a kid and sticking your shovel in the sand a few feet into the lake?" asked Eidt. "For those who remember doing so, it usually didn't work so well. It created a lot of turbidity and the sand always came out with more water than actual sediment that's mechanical dredging. It's not the best for large scale dredging project, but in some cases, it is more suitable than any other method."

Eidt went on to compare and contract mechanical versus hydraulic dredging. The main differences he spoke of between the two was that hydraulic dredging creates much less turbidity than mechanical dredging and helps to maintain a uniform lake floor, where mechanical dredging can create trenches where sediment is removed.

However, hydraulic dredging requires large amounts of unutilized land where the water and sediment mixture can be pumped to settle, and Eidt estimated that every dredging site might require at least 10 acres of land for sediment settling. Eidt also discussed how the piping which is needed for hydraulic dredging cannot be laid across railroads or highways and finding a mile long tract of unused land to lay pipes would can also sometimes be difficult.

Ultimately, Eidt said that large scale dredging more than 40 meters offshore could be most efficiently executed with hydraulic dredging, while mechanical dredging would be most efficient for close-to-shore dredging.

With regards to what factors could affect the cost of dredging, Eidt listed several variables, including: volume of material, sediment texture, sediment quality, type of dredging selected, complexity of reviewers and permits needed, distance to move sediment and whether there are buyers who would be interested in utilizing the sediment for agricultural purposes.

Specific figures for Chautauqua Lake aren't ready yet because not enough information has been gathered.

"Sometimes the sediment comes out and it's rich with nutrients," said Eidt. "Sometimes it comes out and it's mostly sand. It certainly makes it easier if there's someone who is willing to pay for what you're pumping out."

Finally, both representatives ended on a bright spot, stating that other lakes in the state similar to Chautauqua, such as Lake Algonquin, has experienced a moderate amount of success through dredging.

To keep up to date on the Lake Chautauqua Dredging Project or to weigh in on how you believe sedimentation affects the use of the lake, visit www.ecologicllc.com/chautauqua-implementation.html.