The Hallelujah Murders by Dorothy Tell

Poppy Dillworth, feisty star of Murder at Red Rook Ranch, returns in another baffling case...
It's hot June in southern Texas, in a town split over the damming of the Hermosa River. Tension between pro-river and pro-lake supporters is ready to explode.

Christine Jessup is found dead, drowned in the river she was trying to save. Enter sixty-five-year-old private investigator Poppy Dillworth, keen, cantankerous, and with an appreciative eye for an attractive woman...

The women of Hallelujah Bend Camp ask Poppy to investigate, and when the local sheriff says accident, Poppy's instincts say murder.
Assisted by lover and partner Belle Stoner, Poppy, video camera at the ready, indulges in her great love of fishing - for clues, for answers, and even, when she can, for fish in the river. And she's fishing as well for a ruthless killer, realizing almost too late that she, herself, has become prey...