Azusa River
Azusagawa
proper noun
Japanese birch river is Azusa River or simply Azusagawa. Azusagawa is both the Japanese name for the Azusa River, and a Japanese family name.
You learned both of these readings with the kanji. You just need to remember that rendaku turns かわ into がわ.
普段の梓川はとても穏やかです。
The Azusa River is usually very calm.
週末は梓川の水の透明感に癒やされてきました。
At the weekend, I was soothed by the clarity of the water in Azusa River.
梓川さんの歌唱力が高いのは勿論だけど、曲の歌詞もすごくいいんだよね。
Of course, Azusagawa-san is a talented singer, but the lyrics of her songs are also really good.