Cypress Creek Water Quality
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Fairly rugged terrain, narrow canyons, and springs dominate the landscape around Cypress Creek and contribute to its natural beauty. The terrain also reflects the underlying karstic, faulted, and fractured limestone geology of central Texas. The limestone geology creates fissures and fractures that store vast amounts of water underground. The Wimberley Valley is entirely dependent on the Trinity Aquifer for its water supply, which is pumped out from underground through wells and delivered to homes and businesses. Rivers and streams, like the Cypress Creek and Blanco River, are almost entirely dependent on water from the aquifer, too. The flow of these streams will swell during wet periods, but recede again when there is no rain. The water that remains during dry periods comes directly out of the Trinity Aquifer through springs and at places where the base of the river intersects the level of the aquifer, or water table. The picture below illustrates how the groundwater and surface water are intricately connected here.
Water quality in the Wimberley Valley is very dependent on these two factors: water running over the surface after rainfall, and water coming out of the aquifer to feed seeps and springs. Water quality is a concern because adequate temperature and enough oxygen in the water are essential to maintain fish and other aquatic life, low bacteria levels are important for people to swim and recreate safely in the creeks, and nutrients need to be in balance to keep aquatic life healthy and to prevent too much algae from destroying the beauty and health of the water. In general, good water quality in the Cypress and Blanco Rivers near Wimberley is very dependent on a continuous supply of clean, clear base flow from its many seeps and springs.
Water in streams can also directly affect water quality in the aquifer because of rapid recharge through fractures and sinkholes in streambeds. Nonpoint source (NPS) pollution is a term that describes diffuse nutrients, bacteria, and other pollutants that can be part of infiltration or surface water runoff from development, animal waste, failing septic systems, treated effluent irrigation systems, spills or dumping of chemical pollutants, fertilizer or pesticide applications.
Watershed protection, or water catchment protection, is critical to reduce nonpoint source pollution and to maintain the health of the Wimberley Valley and the streams and springs that give it life. Protection of the entire area that contributes to the stream (the water catchment) is important because of the direct and well-established connection between what happens on the land and what ultimately ends up in the water.