A ridge of hills splits Bridgewater down the middle: six watersheds drain west into Newfound Lake, six drain east into the Pemigewasset, and none of them stop at your lot line. Water trouble here comes from the hillside above the house, wetlands in the saddles nobody mapped, and brooks the town gives a 50-foot setback. We find where it’s coming from before we sell you a drain.
Bridgewater Mountain is the divide. The town’s own plan counts twelve separate watersheds, split six and six across that ridge, and it says as much as 10 percent of the town is wetland — not just down low, but in pockets and saddles all through the hills. That’s why a dry-looking hillside lot above Shore Drive turns out to have a spring under the garage. The water table there follows the bedrock, and the bedrock is close.
The town names its brooks in the setback rule: Dick Brown, Woodman, Clay, Whittemore, Great, Fogg, Able, and Tilton. No structure within 50 feet of any of them, same as the lake and the river. Clay Brook and Dick Brown Brook also carry mapped floodplain, so a drainage plan on those parcels isn’t just about the basement — it’s about not putting fill where the brook needs to spread out in April. State wetlands rules cover anything we touch at the brook edge, and Dig Safe covers everything else.
On the lake side the reason to care is phosphorus. Newfound is deep and clear, and it stays that way because not much runs into it. Every roof and driveway on the east shore sheds toward the water, and the Lake District caps lot coverage at 30 percent partly for that reason. Inside the 250-foot Shoreland band the state limits impervious cover and wants runoff handled on the lot. A gravel driveway that runs straight down to a camp on Whittemore Point is a stormwater pipe with no filter. We fix those with infiltration — a trench that lets the water go into the ground instead of the lake.
River Road is the opposite problem. The ground is sand and gravel over the aquifer and it drains almost too well, so the drainage question there is usually the Pemi coming up, not the roof coming down. Flood-prone from Hammond Hill south to Able Road, per the building inspector. Foundation drains there need somewhere to go when the river’s high, and that’s a design conversation, not a French drain.
On a Bridgewater hillside, the cheapest drainage fix is the one done uphill. A hundred feet of curtain drain above the house beats any amount of work at the foundation wall.
We come look when it’s wet. A dry August walk tells you almost nothing about a Bridgewater hillside; a walk during a March thaw tells you everything. We follow the water uphill until we find where it enters the property — a seep at the ledge line, a ditch the road agent’s culvert dumps into, the neighbor’s new driveway. Then we know what we’re intercepting.
Most hillside fixes here are a curtain drain across the slope above the house: a trench to below the seep, perforated pipe in stone, fabric-wrapped, daylighted to a spot that’s legal and downhill. On a small lake lot that spot is often a dry well or an infiltration trench, because the only downhill is the lake and the Shoreland rules won’t let you pipe to it. Near a named brook we stay outside the 50 feet and let the water get there the slow way, through the ground.
Then grading. A lot of what we’re called for is a camp yard that was leveled with fill fifty years ago and now tips toward the house. We regrade to fall away, add a swale to carry the roof water around, and put the loam back. Culverts under driveways get sized for a real melt, 15-inch minimum, and set so the road agent’s ditch still works.
Curtain and French drains in Bridgewater run $2,000–$8,000 depending on length, depth, and how far the daylight is; regrading and daylighting downspouts usually less. Infiltration trenches on lake lots and floodplain work along the river are quoted after we see the water moving. Flat price, no per-foot surprises.
Because the hill is a watershed and your foundation is the first thing in the way. Groundwater follows the bedrock here, and it’s shallow on the slopes above Route 3A. A curtain drain uphill of the house, cut to below the seep and daylighted, intercepts it before it reaches the wall. Waterproofing the wall alone just moves the problem.
No. Inside the 250-foot Shoreland band the state wants runoff managed on the lot, and the town’s coverage cap and 50-foot setback back that up. We build an infiltration trench or dry well sized to the roof area so the water goes into the ground and the phosphorus stays out of Newfound. It usually costs less than pipe anyway.
If it’s one of the named brooks — Dick Brown, Woodman, Clay, Whittemore, Great, Fogg, Able, Tilton — nothing structural within 50 feet, by town rule. Any work at the bank itself is a state wetlands question. Clay Brook and Dick Brown Brook have mapped floodplain too, so we don’t fill there. Drainage outlets stay back and let the ground carry the water in.
Yes, and it’s common on the point, where yards were leveled with fill decades ago and settled the wrong way. We regrade to fall away from the foundation, cut a shallow swale to carry roof water around the building, and re-loam. On a tight lot the swale ends in a dry well so the neighbor doesn’t inherit your water.
That’s a different problem: the ground drains fine, but the river comes up through it. From Hammond Hill south to Able Road the town flags the area as historically flood-prone. Foundation drains need an outlet that still works at high water, sometimes a sump with a check valve. We’ll be straight with you about what a drain can and can’t do there.
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