Water Quality Update

Submitted by John Buttrick, WWA LLMP coordinator

Like people, lakes age. It is inevitable. For lakes, aging involves filling in with run off debris and plant matter, eventually becoming a marsh and then a meadow. Ideally, this is a VERY slow process over thousands of years, but human influences can affect the speed of the process. For people and lakes, the most we can do is to try to slow down the aging process through “best practices” and monitor the results of our efforts with an annual physical.
Other issues of the Zephyr have highlighted the work of our volunteers in areas such as land stewardship and Milfoil remediation.

The Wentworth Watershed Association (WWA) in association with the University New Hampshire Extension Service (UNH) “Lay Lakes Monitoring Program” (LLMP), has an extensive water sampling effort designed to monitor water quality and to identify sources of potential contamination. Thanks to a number of WWA volunteers, recurring water samples are collected, frozen and sent to UNH for analysis throughout the season.

UNH has just released 2021 SAMPLING HIGHLIGHTS reports for the water bodies in our watershed. The reports (3 for Wentworth and one each for Crescent and Sargent’s) will eventually be available on-line for your review, but for now the results can be summarized as:


It looks to me that things are mostly in good shape. There are a few points that I would like to highlight:

• All the testing locations show a long-term decline in transparency.
• In the Crescent report, the long-term trend, since 1984, for Phosphorus and Dissolved Color shows an increase, but the results since 2017, show a decrease. That says to me that the Crescent folks must be making progress in controlling run off.
• In Sargent’s Pond, Phosphorus levels are high. According to Bob Craycraft at UNH, that may or may not be a problem, but less is always better than more and every opportunity to restrict Phosphorus rich run off should be pursued. It is encouraging to note that the Phosphorus does not seem to be resulting in high chlorophyll, a marker for algae growth. What is of critical importance is to routinely monitor the water quality.
•  2021 was the first year that Sargent’s was included in the LLMP thanks to Tom Cookson, who was not able to continue for 2022. Julie Brown and I sampled once in July and again in August this year, but it is really important that we find a team who is able to sample Sargent’s on a regular basis, ideally two people and a rowboat. Please contact the WWA office if you are interested.
• Low oxygen levels in Wentworth have historically been a problem. Due to the pandemic, UNH did not sample oxygen (which requires specialized equipment) in 2021, but is scheduled to do so this fall. Low oxygen negatively affects the cold-water fish that live in the deepest parts of the lake.
•  This is the fourth year that Sara and I have been sampling in Triggs Deep. We really enjoy the process and an excuse to get out on the lake once a week. I have been recording some of the data we gather. I find it noteworthy that each year the maximum water temperature at 1 meter has been warmer than the year before going from 25.7°C in 2019 to 28.6°C in 2022. Four years is too short a time to draw any conclusions about long term trends, but I don’t like the direction.

A question I always have is how does our watershed compare to other lakes. In his talk at the 2022
WWA Annual meeting, Bob Craycraft provided these charts:





In conclusion, as with our human bodies, lake health is partly genetics, which we can do nothing about, and partly lifestyle, which we can. We need to take what we have to work with and do whatever we can to try to slow down the aging of the lakes and the warming of the planet by reducing unfiltered run-off, pumping our septic tanks and moving, as we are able, to reducing greenhouse gas emissions.

Evil Weed: Variable Milfoil 
 

Thank you to our Lake Hosts

Volunteers have been busy at Mast Landing boat ramp throughout the summer offering courtesy boat inspections while reminding people to clean, drain, and dry their boats when transferring from one waterbody to another. In fact, performed 1400+ inspections this year. Their efforts help curb the spread of  Aquatic Invasive Species. We are grateful for the many hours of hard work. If you are interested in joining their ranks, let the office know, we always need more Lake Hosts.