Lake Level - Science, Art or Luck

[Steveo]

Sorry to have to do this but it is that time of year for our traditional lake level thread. But different from prior years I would like this to be an educational thread versus a bashing of the Lakeport dam.

I noticed that the lake level is fairly low like it was last year at this time. We had a lively discussion on the topic with several jokes about increased property lines, no boat access, etc, etc.. The jokes turned to tears when the heavy rains came, with beach and soil erosion and structural damage.

This year I would rather know more about the "science, art or luck" of the lake leveling process. I have several question, maybe you have a few too:

Traditionally the lake level is brought down in the fall. The reason has always been given as - preparation for the influx of winter precipitation and allowing lake front owners to work on water structures. My question is, is there a science to what the lake level should be. Is there any consideration to long range precipitation forecasts or is it just a set height on a set date. Do current Lakeport dam outflows take in consideration the snow pack or the overall precipitation that occurred over the past winter.

Further, is there any consideration as to downstream requirements or restrictions? While the lake is low now the Merrimack River is quite high. Is there coordination between Lakeport dam and downstream entities?

Still further, is there any consideration given to upstream inflow. While the Merrymeeting River inflow can not be controlled, is there any controls on the inflow from the Squams.

Some might find this boring but I'd rather turn this thread into a positive then its traditional bashing.

[jrc]

This might be a good place to start:

http://www.winnipesaukee.com/forums/...6454#post26454

KEEPER is the dam keeper and the documents he attached have a lot of good info on how and why they control the dam and water levels.

[Merrymeeting]

and if you look at Bizer's lake level chart, you'll see that the level is right on track for this year....so far.

http://www.bizer.com/bztnews.htm#lakelevel

[Skipper of the Sea Que]

Originally Posted by Steveo

Lake Level - Science, Art or Luck

Management of the Lake level IMHO takes science, art and includes a lot of SKILL.

jrc pointed the way to info already posted by Keeper. I found the info revealing.

It's a complicated task but I haven't needed to use my mud prop for a long time

[Bizer]

Originally Posted by Steveo

Do current Lakeport dam outflows take in consideration the snow pack or the overall precipitation that occurred over the past winter.

Yes. There are several places where the snow depth and density are measured periodically.

Originally Posted by Steveo

Further, is there any consideration as to downstream requirements or restrictions?

Yes. Many of the decisions for Lakeport are made elsewhere. Winnipesaukee is a reservoir for those downstream. As an example, during the deluge that occurred last May, the Lakeport Dam was held back for a few days while the Merrimack was over flood stage. Winnipesaukee may have been eighteen inches over normal, but the Merrimack River in Manchester was four feet over flood stage.

Originally Posted by Steveo

While the Merrymeeting River inflow can not be controlled, is there any controls on the inflow from the Squams.

Squam Lake does not flow into Winnipesaukee. The flow enters the Pemigewasset River in Ashland.

[Merrymeeting]

Originally Posted by Steveo

Still further, is there any consideration given to upstream inflow. While the Merrymeeting River inflow can not be controlled

Also the Merrymeeting River inflow is contolled. The river starts at the Merrymeeting Lake dam, which is monitored and managed by Fish & Game. They control the dam flow since it has a large impact on the fish hatchery just below the dam.

Merrymeeting was kept high for awhile last Spring to reduce the inflow to Winnipesaukee during the floods.

[SIKSUKR]

Originally Posted by Bizer

Yes. . Winnipesaukee may have been eighteen inches over normal, but the Merrimac River in Manchester was four feet over flood stage..

Boy,do I know about that.That 4 feet is exactly what was in my building on the Merrimack last May.

[Merrymeeting]

Now the art comes in...

[Bizer]

I'm surprised that no one is buzzing about the lake's level. The lake has risen 12.5 inches in the past five days. As I write this, the lake's level is 4.52 feet. The lake has risen 1.5 inches since this morning's official reading of 4.40 feet. It's still rising about one tenth inch per hour.

Here is where the "luck" is demonstrated. Whether it's good luck or bad luck is a matter of opinion.

As of last Friday, the bulk of the weekend storm was supposed to miss Winnipesaukee. At that time, it looked like Winni might get an inch or two of rain. Since Saturday, Winnipesaukee received 4.3 inches of rain, more than double the forecast.

http://www.bizer.com/bztnews.htm

[Resident 2B]

Looking at the Lakeport Dam data, the outflow has been increased to about 1100 cfps, but this increase has not had any real impact on the increasing lake level at the Weirs.

Looks like high tide will be early this year.

As soon as this storm moves out, the weather looks to be good for a while. Lets hope this gets the lake level back to normal.

I am sure the folks at the dam are in the middle of a critical balancing act, with the down stream flooding and the Lakeport discharge rate. Not an easy job when the rainfall is twice what was forecasted.

R2B

[fatlazyless]

Even with all the rain, still have a lot a heavy snow on the ground starting in the southern edge of the White Mountains. Not sure how much drains into the lake and how much bypasses the lake by draining into the Pemigewasset. Meredith has very little snow, but 40 miles north it's a thick white blanket everywhere.

So, who needs electricity, just gimme a woodstove and a 5 gallon bucket!

[jeffk]

Originally Posted by Resident 2B

I am sure the folks at the dam are in the middle of a critical balancing act, with the down stream flooding and the Lakeport discharge rate. Not an easy job when the rainfall is twice what was forecasted.

R2B

I live along the Merrimack down in Hudson and the river here is just about as high as it was for Mother's Day last year. One house in our neighborhood flooded last year and I think is in trouble again and our neighbor's shed by the river is half under water. Except for last year, the river has been no where near this high for the last 10 years that I've been here. I don't want the lake too high either but by Thursday most of the downstream rivers will drop below flood stage and we'll be able to absorb a bit more flow from upstream. Very, very, tricky work.

[chipj29]

As Siksukr said in another thread, the Merrimack is very high right now, and it must be extremely difficult to balance the lake level, and the river level downstream. I drive by 2 sections of the river daily, both are very high. On the Concord-Hooksett stretch, it is not quite as high as it was last May, but pretty close. The river is well into the parking lot at the launch ramp near the Bow powerplant. Down in the Hooksett-Manchester end, again very high, but not quite as high as last year. Same situation at the Hooksett ramp, water well into the parking lot, but not as high. I can tell you this...there is a ton of water flowing downstream right now!

[Resident 2B]

I just did some quick research.

The peak flow of the Merrimack River yesterday/earlier today was 90,000 cubic feet per second measured at Lowell. That is a lot of water and too many raindrops to count!

The flow is at 78,000 Cubic feet per second at 9:30 this morning, so the good news is it is going down.

Outflow at Lakeport Dam yesterday was 1,100 cubic feet per second, so we are supplying a bit more than 1% of the water going through Lowell. I would guess a lot of this water is coming from the melting snow pack north of the lake as pointed out by FLL.

Visit this site for updated flows at Lowell:

http://waterdata.usgs.gov/ma/nwis/uv...te_no=01100000

R2B

[SIKSUKR]

I found a great hydrograph site from the NWS.I've been using that to monitor the Merrimack for my Mill building in Manchester.It shows historical river heights from the monitoring station at the 293 bridge.Last year the height was 3 feet below this years crest which corresponds with the flood level in my building.I had 4 feet last year and about a foot and a half yesterday before it dropped last night.But how about this.In 1936 the river was over 15 feet higher than last years flood which would have put it at 10 ft on my second floor!This year was the 5th highest recorded since whenever they started recording.

[Lakegeezer]

Gack! We're nearing that dredded 505 foot level again. This is the third time in 18 months that the lake is experiencing a 25 year high. The good news this time is few large boats are out yet to erode the shore with wake. The bad news, there is still ice floating around to scrape away soil at new high levels. Will this mean another year of high silt and lower water clarity? The ecology of the lake deserves a break for a few years.

[This'nThat]

Originally Posted by Lakegeezer

Gack! We're nearing that dredded 505 foot level again. The bad news, there is still ice floating around to scrape away soil at new high levels.

Indeed, LG. At 9:00am today, no wind and lots of blue lake in Alton Bay. By 12:30, the wind picked up and the ice started moving. I timed it at 1/2 foot per second. It moved towards shore, and as it hit, there was loud grinding all along the shoreline and into the fixed docks. Here's the picture, now, as the ice has spread all across the bay.

Update: The second picture shows how rapidly the ice flow moved South in Alton Bay today. The second picture taken at 3:00pm. Ice Out is getting very, very close.

[CanisLupusArctos]

According to a data page on NH-DES's web site (http://www.des.state.nh.us/dam/graph/chart2007.htm) it appears that the lake level has broken a record high for this date by about 0.19 ft. Now stands at 504.83 ft. as of 8 AM today. Lakeport Dam has increased the discharge to just under 1,800 cfs but the last estimate of the inflow (made on Apr. 17) was over 9,000 cfs. I would guess most of it's coming in from below - just like it's been doing in everyone's basements the past few days.

Checking the historical graphs on thier site it looks like last May's high was 505.5 feet and the all-time high (since 1982) was 505.9 feet.

[Mee-n-Mac]

Fun ? Seems like a Spring ritual now. Get the snow off the dock. Put 30+ gal barrels on dock. Fill with water. Watch dock disappear under the lake. See neighbor's docks go "mcduding" on by. Watch rock bass swim up 28A. Listen to perch complain about no new beach @ Alton.


ps - is it still Ice Out if the Mount can make to all it's ports but has to be restricted to NWS ?

[Mee-n-Mac]

Forget one sure sign of Spring ....

http://www.winnipesaukee.com/photopo...=11194&cat=523

[Merrymeeting]

Highest level recorded in April according to Bizer records. The good news is it's finally heading down again.

Hopefully the rest of the Spring will only show normal rain levels.

[CanisLupusArctos]

According to NH DES the lake is finally starting to recede, after a week of no rain at all. Strangely enough the warm temps caused a rapid snow melt that helped keep the lake level high.

The real irony is that yesterday and today we've had fire weather watches issued by the National Weather Service - from floods to fires in 7 days. Amazing.