Protecting and Preserving Black Lake and the Surrounding Watershed

P-11730 – Alverno – Black Lake Levels Testing

The testing to bring the headpond (at the dam) down to the 608.5 mark began this past Sunday (March 5, 2017). By 6:30pm that day, we had the spillgate at Alverno open to 13 inch height opening and the units running at about 60% gate opening (and cavitating). Flow indications had flows (total) from the spillgate and units (powerhouse) at a combined flow of 950 cubic feet per second (cfs). However, please note that these flow measurements taken from a computer table for spillgate opening and wicket gate opening and were made several years ago when the headpond was at the 612 mark, or a head differential between pond and tailrace level of approximately 18 feet. Since the pond was actually at 608.5 and the head differential (from headpond to tailrace level) was at about 14.5 feet on Sunday, really the flow, therefore is reduced by approximately 20% to the 760 cfs mark.

Please note it is hoped that should the USACOE take the county up on the county’s request to re-do the 1965 report (at least a portion of it), then the USGS, on behalf of the USACOE could redo the table/curve for various spillgate openings and wicket gate openings at the Alverno Dam.

At this point on Sunday the 5th of March, we were running Kleber in such a way that we were passing approximately 450 cfs into the river, upstream of the lake.

So – what happened since Sunday evening at 6:00pm?

  1. Warm weather came and even rain
  2. Flows from Kleber have increased to over 1,000 cfs (we now have the units at Kleber running full out and the tainter gate open at 1.88 feet, at Kleber.
  3. The Lake levels have increased as follows:
    • Sunday at noon – Black Lake was at 611.72
    • Monday at noon – Black Lake was at 611.75
    • Tuesday at noon – Black Lake was at 611.9
    • Today at 9:00am – Black Lake was at 612.00
  4. We achieved a steady state situation at the Alverno Dam at the 608.5 mark and in essence, haven’t stopped delivering approximately 750 cfs downstream.

In fact, last night and this morning our powerhouse tripped off line because the turbines were starving for water and in fact, because we have no automated control at the 608.5 level, the turbines in fact drew the pond down to about 608.3. This says that we were likely drawing more water than Smith Rapids could give us (not much more – but certainly a bit more – otherwise the pond would not have dropped). And, because we could not draw more than 750 cfs without dropping the pond, then the general numbers that the 1965 USACOE report puts forth seem to be accurate and the statement/conclusion that Smith Rapids is definitely a restriction and is the real control of Black Lake can be made. At 612, the table in the USACOE report says that Smith Rapids can only pass about 750 cfs. This correlates well with what we have been putting out at the powerhouse/dam over the last few days and could put out at the powerhouse to keep the system in balance (i.e. the pond stable at whatever elevation – it doesn’t matter – whether it is 610.2, 609.5 or 608.5 or some lower elevation). The fact that Smith Rapids is the restriction can be further substantiated by the fact that the Lake was coming up over the last few days and yet, we had our turbines and spillgate, more or less at the same settings through the last few days and the pond was at more or less the same 608.5 elevation. Smith Rapids is the restriction. If it wasn’t the restriction, that additional water into the lake would have flowed aggressively past Smith Rapids and onto the powerhouse thereby aggressively raising the headpond at the dam.

In conclusion, we can assert that it would be futile to continue this experiment and, with certainty, futile to go even lower. As we put forth on our USACOE communiqué update on March 7, 2017, we hope that the County will support with a signed letter to the USACOE requesting they embark upon a engineering and field re-assessment of Black Lake, Black River, Smith Rapids and the Kleber and Alverno Dams/Powerhouses as they relate to flows and dust off the 1965 report as it appears that the general public is not satisfied with the 1965 report.

Further, BRLP will at this time go back to its historical winter headpond operating level of 610.2 as it is clear that running the pond at 609.5 did not alleviate higher water levels either on Black Lake. We are headed into another week of cold weather. We will re-assess the 610.2 operating level at the headpond when mild weather hits us again. Additionally, when water levels in Black Lake begin to rise with the final approach of the beginning of spring in the next couple of weeks – we can quickly draw the headpond down if it would be helpful. We have seen that at levels below 610.2 it isn’t and Smith Rapids is in full control.

Lastly, the idea that we missed our opportunity in November of 2016 to get the lake down to the 610.2 mark has been put forth to us. We at this time our highly doubtful that this is the case. Again, I would urge the BLA and BLPS to clarify with its members as to the context of the court order – it was given to Cheboygan County at the time and it was made by the judge in the context that the Smith Rapids would be “dredged” and reconstructed. That never happened. We will, though, assuming the general public is in support, consider an aggressive campaign on October 15th, 2017 to bring the lake to a winter level, two weeks ahead of our normal drawdown period.

We will continue to work with the BLA and BLPS and hope that the County will commission the services of the USACOE to re-do the 1965 work so as to satisfy the concerns of the general public and to determine, without question, what is happening at Smith Rapids.

In closing, we feel that the following conditions are required so that the system and Smith Rapids can effectively lower the Black Lake to the target point of 610.2

  • low fall flows
  • cold weather in November and sustained cold weather through the winter
  • no real mild spells and warm ups through the winter

Should fall flows be present or should we get a mid-winter thaw, the lake will climb back up and we won’t be able to do anything about that at the Alverno dam and those levels will stay high unless a lengthy deep freeze occurs.

— Nelson Turcotte, Black River LP

Posted on March 9th, 2017 in Announcements. Tagged: ,