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Public Meeting Discusses Results Of Dredging Study

By Staff | Aug 11, 2015

AYRSHIRE A public meeting in Ayrshire Friday evening, July 31, revealed the results of a diagnostic and feasibility study on dredging of Silver Lake. The report, which was actually completed in late 2014, has been under study by the Silver Lake Improvement Project Organization, who hosted the public meeting.

The Iowa Department of Natural Resources conducted a private meeting with the Silver Lake Improvement organization in June of this year in order to explain the report’s findings.

Measurements and sampling at Silver Lake were conducted between April 28, 2014 and Dec. 31, 2014, by the Ecology, Evolution and Organizational Biology Department at Iowa State University in Ames. The study concentrated on water quality results and sampling of water and sediment levels in the lake, along with mapping of sediment to determine the distribution of sediments in the lake.

During the study period, water samples were taken from three sampling locations around the lake and probing to measure sediment depths was done at pre-determined locations around the lake. In the water sampling and testing, levels of nitrogen, total phosphorus, chlorophyll a, and total suspended solids varied considerably thorough the time period, but were also similarly spatial throughout the lake, according to the data furnished in the report.

In discussing the findings of the study, members of the Silver Lake Restoration Project Organization highlighted some of the most notable points.

“Something that I found unbelievable is where most of the phosphorus comes from in the lake,” commented committee member Monty Leu. “Do you think it comes from runoff? Wrong, it comes from the air, the atmosphere – Something like 80%.”

“We always thought that when it rained that it helped the lake, but the problem is there is so much dust in the air that when it rains it is worse for the lake.” Added committee member Jo Klooster. “When we had all that rain last year and we thought the lake should be good, it really just destroyed the lake. But this year, the lake is better.”

Water clarity was also addressed in the report, which cited wind as a factor in the water clarity of the lake. Data indicated that transparency of the water in the lake varied throughout the Spring and Summer. The report noted “wind induced mixing may strongly influence the spatial differences and are more obvious during the early part of the ice-free season.”

The report also indicated that measurements of the sediment in Silver Lake average 4.5 feet deep.

It was noted that the DNR would like to see the Silver Lake organization form a Steering Committee to actually guide a restoration project of the lake, while acting as a liaison between the public and the DNR.

A study detailing numbers of carp and rough fish in the lake has been completed and data is being compiled for release early in 2016, along with the final report that details actual recommendations for restoration of the lake.

“Five years ago people would smirk when talking about dredging Silver Lake,” noted Ed Noonan, a member of the group. “Today, they want to know why it’s not done yet.”