by R.D. Gainar CEBS – Lake Management Committee Chairman
Your Lake Management Committee is committed to evidence-based management practices but is also careful to consider comments made by residents. Questions continue to be raised comparing the dredging activities at Grand Lake St. Mary’s (GLSM) to our lake water quality activities by a very few residents who continue to favor and promote the former $2+ million plan to hydraulically dredge the shallows to “improve water quality”. However, evidence suggests otherwise so I contacted the ODNR to ask Mr. Scott D. Fletcher, Deputy Chief, Ohio State Parks & Preserves a few questions about the dredging activities at GLSM.
Q: At Roaming Shores all lake front property, with the exception of a few recreation lots owned by the homeowners association are privately owned. Is there any lake front property privately owned at GLSM’s? If so, are these property owners contributing to the program costs?
A: Grand Lake St. Mary’s has a substantial amount of privately owned shoreline. There was no direct cost to property owners; however, there was a significant amount of private money raised locally to support some demonstrations of promising technology, to develop strategic plans for remediation efforts and to provide for public education.
Q: I am confused by the relationship between your use of dredging and chemical treatment to control phosphorus. Your consultants at TetraTech advise that dredging should only be used in strategic places, such as mouths of tributaries where there is significant nutrient buildup because the cost disparity of dredging as compared to chemical treatments ($17,894/ha vs. $564/ha). It would seem to me more efficient and effective for you to skip dredging altogether and instead invest those funds in chemical treatment. Even if you dredge the entire lake in your attempt to control internal release of phosphorus, you would still need to deal with DRP coming in from the watershed. Are you dredging primarily to increase the lake depth as opposed to controlling internal phosphorus release?
A: Excellent questions. Regarding dredging, the purpose of the program is actually to maintain navigation for safe boating. This is dictated by the funding source (gas tax) that’s used to operate the dredging program. As such our efforts focus on channels, the mouths of navigable streams and other areas that primarily support boating. The minimal benefit in reducing nutrients in the lake as a whole is a net positive one, but not the focus of the dredging program. If were using dredging to address the nutrient issue we would probably focus on the deepest portion of the lake and not the shallow areas where most of the work is currently done.
Q: What percentage of the lake has currently been dredged?
A: Off the cuff I would estimate that the percentage of the lake that is dredged in any single year is probably less than 1%. A program that includes three dredges that generates about 300,000 cu. yds. of material on the 12,500 acre lake is a limited, targeted program.
Q: If you could do only one thing to improve the water quality at GLSM’s
what would that be?
A: We would stop the inflow of excess nutrients to the lake. Controlling the watershed is the key to remediating the conditions
in the lake.
