Why We Are Required to Use Surface Water: Subsidence

A recent University of Houston report shows parts of the Cypress Creek watershed in the Spring area have experienced significant subsidence, which can worsen flooding and change drainage patterns, as well as cause damage to property, pipes and roads. As of 2021, an average of 4.2 feet of land sinking has occurred in Spring over the last century, with most of the land movement occurring since 1987. This subsidence is due to population growth and development and the resultant pumping of groundwater from the area’s aquifers (large, underground water-bearing rock), which compacts sublayers of clay and silt in those aquifers. Today, about 70% of water usage in northern Harris County comes from groundwater pumped from the Gulf Coast Aquifer System.

To prevent subsidence from worsening in northwest Harris County, the North Harris County Regional Water Authority (NHCRWA) treats Lake Houston water and turns it into drinking water for municipal utility districts, including Harris County WCID 114 (the District). The NHCRWA is required to reduce groundwater pumpage to no more than 40% of the area’s total water usage by 2025. In this regard, the NHCRWA is in the midst of a $1.4 billion expansion to its Water Purification Plant in Humble which, upon completion in 2024, will increase treated water capacity from 80 million gallons per day to 400 million gallons per day.

But construction, maintenance and operation of NHCRWA’s treatment and distribution facilities don’t come cheaply: By far the largest part of your monthly water bill is to reimburse the District for the cost of water delivered to it by the NHCRWA. And the District doesn’t have a choice—it is mandated by law to use surface water provided by NHCRWA which, in the long run helps reduce subsidence but, in the short run, is hard on our wallets.