Fantasy book series about persecuted people with elemental magic powers

Question

I'm looking for the name of a series of books (and/or their author), written in English. The storyline followed the last surviving members of a race(?) of people with magic powers corresponding to the classical four elements, residing in an otherwise typical fantasy world. I think there was some kind of church organization that condemned these people to death if found.

The first book followed a young woman with "water" powers, which translated primarily into being able to heal people. The memorable feature is that for the main character, employing her healing power required her to square off on some kind of spiritual plane with a sea serpent-like monster representing death. The first book opens with her living a solitary existence on the edge of the sea and occasionally healing people. The second book involved the heroine of the first book finding and taking charge of a young girl with fire powers. The second book at least left open the possibility of a third book, but I never read it, and don't recall noticing if it had been published.

Other random clues: I read the first two volumes some time around 2008, although if I had to guess they were probably written in the 90s. Fairly sure the author was female, and likely near the beginning or end of the alphabet (I got the books from the library; I have a visual memory of picking them up from one end of the sci-fi/fantasy shelves, which would have the beginning of the alphabet on one side and the end on the other). I think cover of the first book featured a woman fighting a sea serpent.

EDIT: Some further details I can recall (partly because they differ from the first answer I got): The first book definitely featured only a water person. Besides the fire girl mentioned above, an earth person appears around the end of book 2. Fairly sure all the magic people were female, though whether that was part of the worldbuilding or just coincidence, I don't know. I do remember that whatever wiped out the magic people happened a while in the past of the story, and the land was currently at peace. The first book had some kind of typical romantic subplot between the water heroine and the local prince/duke/male-royalty-person. This would seem to rule out the Elemental Logic series pointed out in one answer, which based on descriptions appears to feature a variety of LGBT relationships (which is cool, but doesn't match my recollection of this particular series).

Answer 1

I found it! The series is "The Witch of Two Suns", by Diana Marcellas . The first is Mother Ocean, Daughter Sea, the second is The Sea Lark's Song. There is a third book Twilight Rising, Serpent's Dream, which I never read.

A summary of the first book:

The shari'a people are an ancient race-a proud and gentle people, ruled by witches who harnessed the powers of the world for the benefit of all. When the seafaring Allemanii tribes came to their shores, the two races lived side by side for generations, staying apart but trading and learning from each other in peaceful harmony. But something went horribly awry and the shari'a people were suddenly and brutally slain by the settlers who had come to dominate the land. They feared the shari'a . . . and more important, the witches who led them and who held powers that the Allemanii could barely comprehend. The remnants of this gentle people were scattered, and any shari'a who held the knowledge of the old ways and powers were proscribed and hunted to death.

That was long ago, and young Brierley thinks she is the last shari'a witch in the world. She knows what discovery it would mean, but she cannot deny her gifts as a healer; risking discovery, she goes out time and again to bring solace . . . despite the fact that those Brierley saves are the very people who killed most of her race.

No mention of the serpent with the healing (although the title of book three is suggestive), but the main character's name and the plot description rings all kinds of bells.

Thanks to whoever gave the question an upvote today, as that inspired me to try googling again. The search string

fantasy novel healer fights sea "serpent"

produced an Amazon link for the third book as the fourth result.

Answer 2

Sounds like it could be the series Elemental Logic. It’s Earth powers that heal, but the summary for the series sounds similar:

“The Elemental Logic series is set in the world of Shaftal. Some 35 years prior to the first book, Shaftal was invaded by an army of Sainnites who, in an attempt to eradicate the magic which might be used against them, killed all the elemental witches they could locate. However they failed to realise that magic is inherent in the Shaftali and children have been born since who can wield it. Furthermore, the Sainnites have become cut off from their homeland and are subject to constant guerilla action from the Shaftali. Among both the learned, peace-loving Shaftali and the warlike, spartan Sainnites, women and men are equals in all things, including military, and both queer and polyamorous/polygamous relationships are common and accepted.”