LYME CONSERVATION COMMISSION
Minutes - April 5, 2004
PRESENT: Lee Larson, Dick Jones, Paul Klee, Adair Mulligan, CC; Rod Finley, Pathways Consulting; Tom Morrison, Post Pond resident
1. Housekeeping: Approved minutes of March meeting, on a motion by Dick seconded by Paul.
2. Post Pond: Rod presented the results of surveying at the Trout/Clay Brooks area. His charge had been to find out the likelihood of Trout Brook bypassing the pond and discharging directly to Clay Brook in the event of high water. Trout Brook has a 14 square mile watershed which begins at the top of Smarts Mountain, and is one of the larger streams in town. Rod had found a FEMA flood study from 1992-3 which concentrated on Trout Brook and did not look at the channel east of Route 10. He showed the Flood Insurance Rate Map for the pond, which shows the entire area flooded by a 100 year storm. Rod said that when the double culverts carrying Trout Brook below Route 10 reach capacity, water would then run east along Route 10, and then
cross the road in two culverts that would carry it to the pond via the ditch along the pond’s access lane. Rod concluded that, based on the flatness of the area between Trout and Clay Brooks, and the fact that it is very well vegetated, that it would be highly unlikely for a channel to be created between the two. When water rises enough to spread out in this area, its velocity and channel-cutting potential would greatly decrease. If a channel were to be created, the state would want the town to fix it, and reroute Trout Brook back to the pond. There is a four-foot drop between Trout and Clay Brooks.
a. Culverts: Rod recommended that the culverts carrying Trout Brook under Route 10 should not be increased in size, because that would end the flood dissipation function of the ditch east of Route 10. If culverts are to be changed, he recommended enlarging the 18" culvert south of this.
b. Beaver pipes: Rod displayed a diagram of the Clemson Beaver Pond Leveling device, which has an intake device large enough to prevent beavers from detecting a leak. The pipe is to be surrounded by a mesh cage. Rod said that the problem in installing this in the Post Pond beaver dam is that Clay Brook receives drainage from a 14 square mile watershed, and that even a 2 year storm, which includes 95% of the storms experienced in the area, would require a pipe of four feet in diameter, not including the mesh cage. Such a large pipe could not be submerged deeply enough to be effective, and would be very expensive to install. Rod estimated it could cost more than $2000. He said it also would not control the pond level all the time, and if
there is a storm, the pond level would go up. Heavy equipment would be needed to lift the pipe, and it is likely that if a pipe were installed in one dam, the beavers might move their control operations to another dam. It was agreed that it is not economically, politically, or environmentally viable to install a control device in the Clay Brook beaver dams. Lee noted that the dams breached last fall have not yet been repaired by the beavers.
c. Project: Agreed that Rod has done what the CC outlined for the project, and asked him to send a bill which can be paid when it arrives. Project has come in under budget.
3. Moose Plate grant application: unsuccessful, although Ben’s application met the guidelines for the program and not all the programs’ funds were awarded. Lee has written a letter pointing this out.
4. CC membership: News of Ben Hudson’s resignation was met with great disappointment. Members recommended a potential member and will ask absent members for suggestions.
5. Old Business:
a. Natural Resource Inventory: Vickie has contacted the regional planning commission for an estimate on gathering information on 11 x 17" maps. Hope to put this in town plan.
b. Trail maintenance: Hulbert Outdoor Center has offered 10 kids’ labor; agreed to ask for help on rerouting Lower Grant Brook trail, if there is adequate adult supervision. Ben Hudson will help with bridge construction at Whipple Brook on town forest on Trails Day.
6. Site visit: porch proposed at Neal property, in wetland buffer. Lee will set up time.
7. New Business
a. Approved payment of $175 dues to NH Assoc. Of Conservation Commissions and $25 to Upper Valley Trails Alliance, on motion by Dick seconded by Paul.
b. Green Up Day - May 1, Joan and Laura will coordinate. Fees will be waived at transfer station. Will put notice in church news and send email to town list.
c. Trout Pond Management Committee - 3 terms have expired. When Joan can be present, will discuss whether committee is still needed.
d. Scout campsite in town forest - have asked to be sure others using the site will take responsibility for it. Lee will draft a simple permission slip which will include agreement to leave site in as good or better condition, and to carry out all trash.
e. Lake Host program - NH Lakes Association will provide $3-4,000 for a summer intern to patrol the Post Pond boat access if town provides supervision and hiring. Agreed that town cannot supervise this and access is not heavily used.
f. Comments on conservation easements - reviewed advice from town attorney, and agreed that current easement wording is fine. Voted to have selectmen accept the addition to the Big Rock Nature Preserve and grant of easement on former Shelby property as proposed by UVLT, on a motion by Dick seconded by Adair.
Respectfully submitted, Adair Mulligan, Secretary pro-tem
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