Turbidity Monitoring Report 20240731

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Winston, Joey
From:Andy Ferrell <[e-mail]>
Sent:Wednesday, July 31, 2024 5:32 PM
To:Winston, Joey
Cc:Clement Riddle; Troy Lucas
Subject:[External] Cashiers Lake Dredge Turbidity Report
Attachments:7.30.2024_Cashiers Lake Dredge Aerial with Turbidity Monitor Locations.pdf
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Joey,

I hope this email finds you well and it was good talking with you yesterday.

As I mentioned on our call, we discovered over this past weekend that on Thursday, July 18 th, 2024, the
downstream turbidity exceeded the allowable amounts and stayed elevated through Sunday, July 21 st, 2024. We
had approximately 0.35 inches of rain that Tuesday and Wednesday, with the heavy rains beginning on Friday (19 th)
that week and totaling 1.89 inches between Friday (19th) and Sunday (21st). Thursday (18th) was the last day of work
within the lake or related to the lake dredge, and there was no activity in the lake on Friday, (19 th), Saturday (20th) or
Sunday (21st).

On Monday, July 29th, 2024, I downloaded the turbidity data for the week of July 22nd, 2024, and learned that the
turbidity had fallen back within the acceptable range Monday (22nd) and Tuesday (23rd) but on Wednesday, July
24th, 2024, the downstream turbidity again exceeded the allowable amounts and stayed elevated through
Saturday, July 27th, 2024. Between Monday (22nd)and Tuesday (23rd), we had a total of 3.44 inches of rain (mostly at
night) followed by an additional 2.3 inches of rain from Wednesday (24th) to Sunday (28th). Between Friday (19th)
and Sunday (28th) we had a total of approximately 7.6 inches of rain. To try and manage the water that was coming
into the sight the contractor pumped the dredge area on Monday (22nd), Tuesday (23rd) and Wednesday (24th), but
starting Thursday (25th) the rain set in during the day and they ceased all work from Thursday (25th) through Sunday
(28th).

Starting Sunday (28th) and into Monday (29th), when I downloaded the data, the turbidity was within the allowable
range.

I have attached an aerial photo of the dredge work as of Monday, July 30th, 2024, and identified the approximate
location of each turbidity monitors (shown with red circles). The reason for this is because our wetlands ecologist
pointed out that it was a bit confusing see the downstream data higher than the lake data during some of the
spikes, which occurred on Wednesday (24th) through Saturday (27th). Her only thought was that there could be
some naturally occurring erosion that might be flowing into the downstream section during these heavy rain
events.

She also pointed out that the two above mentioned occurrences have been the only times that the turbidity has
exceeded the allowable range and that since the project started at the beginning of June, turbidity has been below
the allowable levels 85% of the time (in days).

Please let me know if you have any questions or need any additional information.
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Thanks

Andy S. Ferrell
Vice President – Cashiers Lake
Daniel Communities
Cell: 980.721.5177
[e-mail]