The title promises a rescue, and the poem delivers a corpse. "Dammed" sounds exactly like "damned", and "saved" can mean rescued or put aside, like money in an account. Pickering's poem is about how the language of law and finance can make the destruction of a landscape sound like good management, and how one small, ordinary body can undo that language.
The first stanza is a single unpunctuated sentence, and its verbs all come from offices rather than from rivers. To "bespeak" is to order something in advance, so the valley was reserved like a made-to-measure suit before anyone arrived. A lake is "bankrolled", a village "revoked" as if it were a licence, farmsteads "foreclosed" like failed mortgages, and a river "distrained", which is the legal term for seizing property to settle a debt. The objects of these verbs are a valley, a village, farms and a river, things people live in and by. The clash between tidy, abstract actions and heavy, physical things is where the poem gets its bitterness. The sequence even loops back on itself: it begins with land and ends with the river, the thing the title says was "saved".
Sound reinforces the coldness. The line lengths alternate almost exactly between four and five syllables, so the stanza moves at a steady, bureaucratic tread. The long "o" of "bespoke", "bankrolled", "revoked" and "foreclosed" chimes from line to line like a door closing, and most of the verbs end on a clipped "d". There are no commas, so the actions pile up without a pause, as if the process had no brakes. There is also not a single adjective, which means no colour and no feeling, only procedure. And "Before this they" quietly points ahead, so the whole list is set up as a prelude to something we haven't yet been shown.
The second stanza breaks the pattern. "In the sun" is almost cheerful, but the sentence that follows lurches: "From on a streaming slab" piles two prepositions together, as if the speaker is stumbling on what they see. "Slab" suggests something hard and man-made, and judging by the imagery it could be part of the dam itself, though the poem never says. "Belly upwards" is the posture of a dead animal, but it also echoes the idiom "go belly up", which describes a failed business. That would fit the commercial vocabulary of the first stanza, whether or not Pickering intended it. Then "here it is" sounds like someone presenting evidence, and the legal frame begins to turn on the people who built it.
The last line is a fragment: "A white dead fish." It has no verb, which is striking after a stanza of nothing but verbs. The people in the first stanza *do* things, and what they leave behind is a sentence in which nothing happens any more. The line is all stressed syllables, so it lands like a dropped weight. The word order matters too. "White" comes before "dead", as though the eye notices the colour first and understands the death a moment later. These are the poem's only real adjectives, and they carry all of its emotion because the poem has refused to supply any elsewhere.
The poem is significant because it never argues. It names no place, no year and no company, which makes it widely applicable: the same pattern could fit any project that moves people and water around on paper before it moves them in fact. It trusts the reader to do the accounting, setting a long list of lawful acts against one small piece of physical evidence. By the end, "legally" in the title sounds less like reassurance than like a confession that being lawful and being right are different things. The poem is also short enough to read in seconds, so its effect comes from contrast alone: a stanza of fluent, official language, then a single dead fish that has no words to say anything back.