Need help translating a poetry (very important)

Hi sorry, I am new and can't find which forum to post this in. Please help me out. I am doing this for my english and I can't seem to understand this poetry. I need some help translating what it means.

The River by Derek Walcott

was one, once;
reduced by circumstance
the Council tends it. Once

it could roar through town,
foul-mouthed, brown-muscled, brazenly
drunk, a raucous country-bookie,

but lately it has grown
too footlose for this settlement
of shacks, rechristened a city;

its strength wasted on gutters,
it never understood the age,
what progress meant

so its clear, brown integument
shriveled, its tongue stutters
through the official language,

it surrenders its gutterals
to the stem, stone Victorian bridge;
reclaimed, it dies a little

daily, it crawls towards a sea
curdled with oil-slick, its force
thins like the peasantry,

it idles like those resinous
wrinkled woodsmen, the country
reek still on them, hoarse

with municipal argument,
who, falling suddenly silent
on wire-bright afternoons, reflect

on mornings when a torrent roared down their gorges, and
no one gave a damn what the words meant

Anyone?

I'm english and I have no idea what that means =S

It's about how a once great river is running low little by little everyday. It mentions an oil-slick leading me to believe that it was polluted as well and then it flowed into the ocean. That's what I got out of it. Good luck.

Oh also this line:

its strength wasted on gutters,
it never understood the age,
what progress meant

Makes me think that everything around the river is becoming more modern which goes along with the oil slick thing they mentioned earlier in the poem. As everything else in time progresses the river seems to become thin and polluted and no one really cares.