Water Speedwell, probably an introduced species, has been added to the USWildflowers database (03/03/2013.) Scientific name is Veronica anagallis-aquatica.  It  is also known by the common names Sessile Water-speedwell, Brook-pimpernell, and Blue Water Speedwell.  Photo below was taken along the Kleinschmidt Grade, Adams County, ID, on May 28, 2012.   Go to the Water Speedwell detail page for more information.

Water Speedwell, Sessile Water-speedwell, Brook-pimpernell, Blue Water Speedwell – Veronica anagallis-aquatica