Tiber Farfa Nature Reserve

In 1977 a dam was built on the Tiber that lead to the creation of marshy lands at the meeting of the small Farfa River.
Born as such, it is one of the most important marshy areas in Lazio and was categorized as a humid zone of international interest by the European Union.
The marshy area is populated by thousands of birds of tens of different species, both migratory and non-migratory. Since 1994 walkways have been added that allow visitors to visit even the flooded zones. We say that the best way to visit the reserve is on foot or by bicycle; in both cases the routes are always flat and simple, suitable even for small children. Take a pair of binoculars to see the birds from the observation points.

Arriving at the Park - You reach the main entrance of the park by means of a downhill street that leaves from the town of Nazzano, 34 km from Via Tiberina, on the right bank of the Tiber. At the bottom of the hill, you'll find the parking area with illustrated signs and two dirt roads that go into the reserve. Take the one to the left that arrives at the Tiber in about a hundred meters distance. From this point all of the paths depart, and in some periods, it is possible to take a little ferry that crosses the river and lets you visit the bank on the right-hand side, the Reatina, and the mouth of the Farfa.
If the ferry isn't running, it is more difficult to reach this bank: you depart from Poggio Mirteto Scalo and head for the bridge over the Tiber, and immediately before you cross the bridge you turn onto the dirt road to the left which goes along a long stretch of the river. Keep in mind that there aren't any signs that indicate entrances to the park different from the main sign in Nazzano.
Follow along the dirt road as far as you can, always staying near the river to not loose yourself in a maze of agricultural roads, until you reach the point from which the paths depart.

Visiting the Park - If you are on foot the most beautiful part of the reserve is the southern part (at the valley). It is better to leave out the large loop of the northern Tiber, which is a bit monotonous (this advice applies to both banks). Instead, if you are on bicycle and the ferry is running (double check!), you could think about taking a trip, crossing the river in correspondence with the bridge near Poggio Mireto Scalo.
Consider that, moving on foot and in absence of the ferry, it will not be possible to cross from one bank of the Tiber to the other within the park because there aren't bridges; so, you have to choose at the beginning to visit the orographic right (the same side as Rome) or the left (the same side as Rieti).
The two banks are very different; so, we will discuss them separately.

The right-bank, the same side as Rome, where you'll find the main entrance to Nazzano.
From here, there is a nice path on a walkway along the river which crosses woods of marshes and reeds; from the path, derivations break of, always off of the walkway which lead to observation areas for birdwatching.
To explore all of the long walkways from one observation area to another is a very pleasant route.
When the path merges onto a dirt road, a stretch begins that, in my opinion, is a bit too monotonous to be an interesting walk. By bicycle, however, it goes quickly and can thus be very pleasant.
If you are on bicycle, you cannot go on the walkways, which are for pedestrians only: if you want to bike, pedal towards the south, from the parking area mentioned above and take the dirt road to the right instead of to the left.

The left-bank, on the same side as Rieti, is a "wilder" place and not as well equipped: fewer paths, no walkways, etc... But it is also the side of the beautiful mouth of the Farfa.
The mouth is in the southern part, easily reachable if there is the ferry. If you arrived by car from the bridge nearPoggio Mirteto Scalo, however, you are not entirely near: on foot, you can plan for a long walk along the river, with a good sense of direction, head directly to the mouth of the Farfa towards the south (cutting the famous loop of the Tiber). On bicycle, you can easily go along the loop of the Tiber.