P-11730 – Alverno Dam – Black Lake Levels Concerns
Good Morning All:
Further to Jim Tucker’s email, I think Jim meant to say on Sunday afternoon when the temperatures get mild from this current cold spell, we will move the head pond down from its current level of 609.89 to the 608.5 level and hold it steady there.
We will do that for 48 hours into Tuesday afternoon. It appears that we will have until Wednesday afternoon for mild weather, then it will be turning frigid again. If we find that the lake level continues to drop, we will likely maintain the 608.5 until Wednesday.
However, we will assess after 24 hours and after 48 hours. We do believe with the warm temperatures Sunday and Monday that the Kleber dam outflow will pick up again.
One thing we would like to state is that after reviewing the USACOE’s 1965 report, it appears at a lake level of 612.0, that Smith Rapids will flow at about 750 cfs. At 611.5 lake level, that Smith Rapids will flow at about 575 cfs (see page 51 of 65 of the pdf document attached). We will know what our flow is out through the spillgate and/or powerhouse at any point in time. If we have a steady state situation and hold the pond at 608.5 – we will know what the flow is at the dam. We will look at the lake at the same time and then check the table on page 51 of 65 of the USACOE report – that, then, will give us a solid comparison and idea of what is happening at Smith Rapids.
Kleber Dam by Sunday/Monday will likely be pushing out at least 575 cfs and that doesn’t factor in what the small creeks/streams, also dumping into Black Lake, will put into the lake. In theory, we likely won’t get the lake down that far. Also, important to note is that if Smith Rapids is truly a restriction and there is this direct relationship between Black Lake level and flow through Smith Rapids, then, it would be futile to draw the pond down at the Dam by opening the spillgate and thereby shutting the turbines down as we can push out up to 870 cfs from the two turbines running full out (so why shut the turbines down at a low level to simply allow the water to pass through the spill gates).
In any event, we agree to try this and see what impact it has on the lake. If we can have a significant impact on the lake by doing this, then it points to a potential long term solution to not worry about the lake through the winter and then just do something like this in late winter/early spring for a stint in future years.
We did a theoretical calculation as follows:
Assume the powerhouse/dam releases 800 cfs at Alverno Dam and that only a total of 500 cfs is flowing into the lake (that is from Kleber (the river) and from other sources – streams, creeks, ground water, melt water). So with a differential of 300 cfs and a Lake area of 10,000 acres (43,560 square feet per acre) or 435,600,000 square feet, we can theoretically calculate the following.
To move Black Lake down 6”, this would be equivalent to 0.5 feet x 435,600,000 sq. feet or 217,800,000 ft3. Therefore, if the Alverno plant/spillgate were pulling out an extra 300 cubic feet/second, it would take 726,000 seconds or 210.6 hours or 8.8 days to take the lake down by 1/2 a foot assuming a steady state situation in terms of inflow into the lake. However, we know, already, that when we draw more water out of the system at the dam, then is coming into it, that the pond at the dam will come down very very quickly. This points to the fact that the Smith Rapids just won’t supply more water and is a restriction.
I thought I would put this forth, as the basic information, that the USACOE presented in its 1965 report, seems to have gotten lost in the last couple of months of grasping at solutions to the problem. We will continue to try various things but the science is the science and the facts are the facts and 52 years of time passing won’t necessarily change it. We are talking to the USACOE and I have been passed onto their Outreach Coordinator in an effort to see what service(s) they might provide to re-evaulate things at Smith Rapids and in the system (i.e. dust off the report if you will).
Again, we will be back to you on Monday and then on Tuesday, again with a status report and update.
Black River LP