TRURO — The Pamet is not just a tidal river but an entire estuarial system — albeit an altered one — that stretches the width of Truro. At its eastern limit is the barrier beach, and it emerges at Pamet Harbor, where its three branches join and flow into the bay through a tidal inlet. Its branches are mostly unseen as they flow beneath roadways and through undersized culverts that restrict the system’s tidal flow.