Ground Water Conversion

The Galveston-Houston area draws its water supplies from underground limestone and clay strata. Unlike many other Texas limestone aquifers, such as those in the San Antonio and Austin area, our areas underground supplies cannot recharge quickly. When water is pumped out of the strata all earth above is slowly compressed and lowered. When subsurface ground is lowered, a process known as subsidence, it changes the way that rainwater at the surface collects and flows.

At the surface, where higher ground naturally sheds water to lower ground and then into natural water channels, the newly lowering ground now collects water and forms new paths that water takes in response to gravity.

Problems with Continued Underground Water Use

subsidence13In a coastal area of relatively flat land running to the seashore, subsidence forms large areas that are more prone to flooding and holding water. Refer to the Harris-Galveston Coastal Subsidence District and the West Harris County Regional Water Authority for more information on this topic.

This natural phenomenon has been occurring over time since the first wells were sunk by early settlers to our area. As more water is pumped to the surface by all users sharing the same resources, areas within the aquifer unevenly begin to sink.

Development for houses, industries and businesses encourages more pavement for sidewalks roads and parking lots. As this surface was covered and no longer available to absorb water to layers below, rainwater runoff increased in velocity and force towards natural water channels. With a less absorbent surface, natural channels filled quickly and often overflowed.

Finally, the problem of supplying additional water for an increasing population grows with the number of people and industries that require water.

Mandatory Conversion Plan

Early pioneers to the Galveston-Houston area had abundant well opportunities and did not immediately need reservoirs. They busied themselves draining and controlling coastal plains for agriculture.

Studies of water use and subsidence have been underway since the early 1940’s. One potential solution to the growing problem is to create man-made surface reservoirs. This solution has been extensively practiced in north Texas. There are only a few natural lakes in the state. Most were created as surface water reservoirs.

By the 1960’s subsidence in the ship channel area could not be ignored. Later, it was shown that neighborhoods in northwest, farther from the coastline, were also subsiding.

In 1999, the State of Texas took action with legislation that required a migration by 2010 from ground water sources to surface water. The plan recommended reservoirs, rivers and streams as new water sources. In our area the City of Houston has authority over Lake Houston, the San Jacinto River and Lake Livingston, the 3 current sources of surface water.

To help accomplish the changeover, new water authorities were formed to aggregate water utility districts to better work with the City of Houston toward achieving surface water goals.

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