Råstasjön - 100 m from a lake.

Råsta sjön aerial perspective, by Jan Ainali CC-license. From wikpedia article about Råstasjön.

 Solna is proposing a series of developments on the north of Råstasjön, a small lake surround by nature and houses. Enveloped by the railroad landscape on two sides. Suburban modernistic housing on one side.  Recently a large arena was built and the surrounding complex with housing, offices a gigantic shopping mall is under construction to the east of the lake. To the north (up in the above photo) and housing are is proposed between the small forest north of the lake and the railroad yard to the north.

The are around the lake is a popular recreational area for the inhabitants of Solna and neighboring Sundbyberg. (I  run around the lake regularly.)

It is also due to its shallow depth and wetlands very popular with avian wildlife. So there are good reasons to carefully consider any future developments potential impact on the lake.

100 m is the general distance defined by the law regarding development close to water.

Andreas Ekegren, a city council member for Folkpartiet, proposes that a nature reserve should be established around the lake following the 100 m line, thereby limiting the consequences of the development and proposing a compromise between developing and preserving. 

100 m zone from lake draw on top of the detailed plan proposal. 

The fundamental problem is of course how to we know that the 100 m limit is relevant, should be more to provide for a greater buffer or could be less? Does it need to be the same in every direction or are the performative differences in the landscape surround the lake?

100 m zone surround the whole lake also outside the detailed plan.

 On the south side of the lake a series of private houses developed a long time ago stands within the 100 m zone, nobody seem to consider them be a problem. Just to point out that the 100 m limit is no magic rule making development safe or unsafe. Of course the development imagined to the north of the lake along a road serving as secondary or tertiary access to the arena complex has different typology than the private detached garden houses to the south. Could a different typology allow a softer border between development and forest/wetlands than what is proposed today?  Yes.