The San Luis Valley Groundwater Basin stretches from San Luis Obispo to Edna Valley — but a toxic chemical swirling in the water prevents the city from using the resource for drinking water. That will soon change, however. San Luis Obispo won a $6.6-million grant to install wells that remove tetrachloroethylene, a chemical also known as PCE, from the groundwater, according to city water resources program manager Nick Teague. The wells should be operational by 2026 and will allow the city to fulfill about 12% of its drinking water needs, he said.