The adjective lomný denoted a frequently bending river, but also a stone suitable for quarrying.

The river flows through the municipal territories of Rožmitál pod Třemšínem, Hvožďany, Mladý Smolivec, Předmíř, Lnáře, Tchořovice, Blatná, Buzice, Lom, Mirotice, Smetanova Lhota, Ostrovec, Varvažov and Oslov.

The object of protection is a pond ecosystem with very well-preserved littoral vegetation and adjacent mesophilic meadows and waterlogged alder forests, which has high biodiversity.

[6] The Lomnice's river bed in the municipality of Smetanova Lhota is protected as the Vystrkov Nature Monument with an area of 2.8 ha (7 acres).

[7] A few hundred metres further downstream, the river bed is protected as the V Obouch Nature Monument with an area of 5.1 ha (13 acres).

The so-called sejpy (man-made mounds that are the remains of gold panning) in the castle park in Blatná are protected as a cultural monument.