Seven Rivers

The story goes that demons,

1. Mahabal 
2. Atibal &
3. Demon army 

created huge disruptions in the world

Brahma, Vishnu, Mahesh were prayed to release the world from their wrath. Vishnu killed Atibal,however Mahabal had the boon of 'death at will'. Hence, the gods requested Adimaya to charm Mahabal. Mahabal said to Adimaya that I will die in your hands only if the 3 Gods agree to reside on earth in our names.

Hence,

1. Brahma in the form of Koteshwar (The demon army) 
2. Vishnu in the form of Atibaleshwar, 
3. Shiva in the form of Mahabaleshwar and  resided here.

https://www.google.com/search?q=Brahma+koteshwar+mahabaleshwar

https://en.wikipedia.org/wiki/Old_Mahabaleshwar

https://en.wikipedia.org/wiki/Mahabaleshwar

Source

http://knowledgefruit.blogspot.com/search/label/SkandaPurana

The 4500-year old Panchaganga temple is built at the origin of 7 rivers - 

1. Krishna, 
2. Koyana, 
3. Gayatri, 
4. Savitri, 
5. Venna, 
6. Saraswati and 
7. Bhagirathi. 

Out of them, springs of the first 5 flow continuously

https://en.wikipedia.org/wiki/Panchganga_River
http://wikimapia.org/2352560/Panch-Ganga-Temple

whereas

1. the spring corresponding to Saraswati comes alive after every 60 years and 
2. one corresponding to Bhagirathi comes alive every 12 years.

https://www.speakingtree.in/allslides/the-beautiful-river-krishna-pushkaralu