A WATCHED SPRING NEVER BOILS? CHARACTERIZING SMALL SUBAQUEOUS ARTESIAN SPRINGS IN LITTLE SALT CREEK NEAR LINCOLN, NEBRASKA

Little Salt Creek flows through northeastern Lancaster County in Nebraska, just north of the city of Lincoln. The creek has high salinity levels, contributing to a number of unique near stream saline wetlands and providing important habitat for the endangered Salt Creek Tiger Beetle. In 2007, the second author discovered numerous subaqueous springs in Little Salt Creek as the possible source of salinity to the stream. These springs are roughly circular and are usually small in diameter--some only a few millimeters. However, larger spring or seep areas are also present, extending up to meters in diameter. Water in the springs comes to the surface with enough pressure to suspend sand and silt particles so that the springs appear to be “boiling.” Gas bubbles are sporadically emitted from the springs. The springs are commonly located on sandy gravel bars or near banks along the creek. Some are also present on the bottom of the stream. Miniature piezometers were used to sample water from the springs and to estimate flow rate. Water samples from the springs were analyzed for major ions,¹⁸O and ²H isotopes, pH, conductivity, temperature, alkalinity, and dissolved oxygen. Samples of the gas emitted were also collected and analyzed. Preliminary results show the spring water to have higher alkalinity and salinity than the stream. The spring water also has neutral pH and low dissolved oxygen. Spring discharge is cooler than the stream water in the summer (about 13°C). Cation and anion analysis and isotope composition will be used to determine if the water issuing forth from the springs is upwelling from the underlying Dakota Aquifer. These results will indicate the impact the springs have on Little Salt Creek salinity and the surrounding saline wetlands. Improved knowledge of the source and quality of the spring water will aid wetland preservation and reintroduction of the Salt Creek Tiger Beetle.