On the crisp, Saturday fall morning of November 5, 2016, members of the PLIA assembled at the telephone substation near Seaman’s Point Road to pick up litter on the highway. They have adopted and are responsible for cleaning up a stretch of roadway along Route 156, which they do twice a year. PLIA Board member John Morin organized the team and PLIA member Steve White coordinated with the State to support the activity. The White family has its own stretch of Route 156 which it also patrols for cleanup. Although the temperatures were frosty, spirits were high as friends and neighbors shared stories of summer adventures as well as plans for the coming winter, all while bagging cans, bottles, and other debris strewn along the road. Community service can be fun!
Those who have been following reports from the PLIA are aware that invasive Variable Milfoil has been in the South Channel for the past two summers. Throughout this time, PLIA volunteers have been snorkeling the area to discover new growths, which they have marked so that DES divers can remove them. At one point, a local volunteer certified diver even donated his time to pull a lot of growth in early July.
As a result of the infestation, we have sent out notices and placed signs in the South Channel advising boaters to avoid the channel in order to minimize the possibility of fragmenting and spreading the milfoil. Currently, all known Variable Milfoil has been removed from the channel.
While it is very likely that the invasive milfoil has not been eradicated completely, the South Channel appears to be clear enough that boating can resume in the South Channel.
Consequently, the signs in the South Channel are being removed. In the spring we will resume searching the South Channel area for new infestations of milfoil and will send out notices and place the signs back in the channel if any new milfoil is found.
The PLIA would like to thank the people who went out of their way to avoid this area and recognize that their sacrifices and inconveniences played an important role in this effort. As we know, it is impossible to stop all traffic through the South Channel, but we appreciate the efforts made by many boaters to avoid using it. We also appreciate all those who answered our call to spread the word, not the milfoil!
Prepared by the NH Department of Environmental Services (NHDES)
Over the last year, NHDES continued its evaluation of Pawtuckaway Lake’s phosphorus, aquatic plant surveys and lake outflow volumes and phosphorus concentrations. Semi-annual meetings were held in spring and fall. A meeting was held September 17, 2015 in Nottingham where the summer relief pulses and the public hearings about the draft 2015 Report of the Instream Flow Pilot Program were discussed.
Lake Drawdown – On October 13, 2015 the NHDES Dam Bureau started the fall drawdown by opening the Drowns gate and removing a stoplog from Dolloff dam, which was subsequently replaced. Most of the flow from Pawtuckaway during the last two years’ drawdown had gone through Drowns. Initially, the target release ratio was 70:30 (Drowns: Dolloff), but later the ratio drifted to a 90:10 split in trying to maximize phosphorus export. However, this has resulted in long periods when the Pawtuckaway River received no flow other than leakage. This is much less than is needed to support that river’s ecosystem. A more balanced release will occur next time while still preferentially releasing higher phosphorus concentrations at Drowns. From October 30 to November 1, NHDES rerouted all outflow through Dolloff Dam when Fish & Game Department requested that alewives needed egress from the lake over Dolloff Dam. NHDES and NH Fish & Game are conferring on how to operate the drawdown to support the alewives’ migration out of the lake.
2015 Phosphorus values – Phosphorus export during the fall of 2015 was significantly less than in 2014. From October 10 to December 3, 2015, 211 pounds of phosphorus were released from Pawtuckaway Lake during the early stages of the lake drawdown, compared to 1066 pounds in 2014 as a result of lower phosphorus concentrations and less water entering and leaving the lake. The volume released from the lake in 2015 was 37 percent of 2014’s volume, and the peak phosphorus concentration at Drowns Dam outlet in 2015 was 40.2 ug/L compared to 2014’s concentration. NHDES is looking into the reasons for lower phosphorus concentrations in the lake.
Wiswall Dam water use – Under the UNH/Durham Water System’s Instream Flow Program water management plan, UDWS must stop withdrawing water from the Lamprey River whenever flows at the USGS gage fall below 16 cfs. UNH has developed a website at http://energy.sr.unh.edu/water/ which shows UDWS’s water withdrawals from Wiswall Reservoir and the reservoir levels. The lake level drawdown for 2016/2016 target will be -5 feet (minus 5 feet).
Click here to read the full report (PDF): 2016-plia-article-from-des