Wednesday, March 29, 2023

Sustainable Water

 On Tuesday, the Committee of 100 held:

A Panel Discussion on the Quality & Quantity of

Water Resources in the Prince William Area

I was honored to be one of the Panelists along with Dr. Stanley B. Grant, Professor and Director of the Occoquan Watershed Monitoring Laboratory (OWML), Greg Prelewicz, Planning Manager at Fairfax Water, and Lazaro Gonzalez, Director of Global EHS and Sustainability, Micron Technology. Below are my comments:

As seen from space, we are the blue planet covered with water.

Yet, there is no mechanism on Earth for creating or destroying large quantities of water.

The most fascinating thing about water is that the water we have is what's been here, literally, forever- since the planet was formed 4.5 billion years ago.

Though 3% of the water on earth is fresh, only ½% of the water is available for us to use. The rest of the fresh water is locked away in ice, super deep groundwater or polluted beyond redemption.

The available supply of fresh water is renewed by the hydrologic cycle or artificially replenished by the activities of mankind.

In its most simplistic terms Rain drops fall to earth and will either evaporate, infiltrate into the soil, recharge groundwater or flow along the ground to a stream and ultimately flow into rivers and to the ocean-moving always moving.

But many activities of mankind interfere with the hydrologic cycle

The need for water is constant and grows with population and wealth

A community or society becomes unstable if water resources are inadequate to meet the needs of the community by growth in demand or reduction in supply- often both.

The Potomac River, its tributaries, reservoirs and the associated groundwater resources are the source of drinking water for the over 6,000,000 people in the Washington Metropolitan area.

A little more locally, the Potomac River and the Occoquan Reservoir are the main supply of water for Fairfax Water which also supplies Prince William Service Authority and American Water

Water supply in Prince William County is a mix of water from the Occoquan Reservoir, the Potomac River, groundwater and Lake Manassas.

And yet our water supplies are connected to each other and the land

The Occoquan Reservoir was built 1960’s expanded to its current capacity in the 1980’s.

The Occoquan watershed is often described as the most urbanized watershed in the nation.

Think about that for a minute, certainly there are far more urbanized areas in the United States, but they do not have functioning watersheds. During their growth and development cities across the nation confined and subsumed many thousands of streams, erasing them from public memory leaving only stormwater.

Water comes into the Occoquan water basin from rainfall (and melting snow) . The streams and creeks of the watershed come together at Bull Run and the Occoquan River to deliver the water to the Reservoir. Groundwater is part of this system maintaining the base flow of the rivers.

There is no longer enough water in the rivers to meet the demand, the Upper Occoquan Service Authority, UOSA, -the waste water treatment plant also delivers 40 million/day of recycled water that originated in the Potomac River to the Occoquan Reservoir. Supplementing the supply.

Our Climate is changing. Locally, average rainfall has been increasing. Over the last 30 years it increased slightly to approximately 44 inches per year. Climate forecasts for our region by the ICPRB project us to get wetter with more intense rainstorms - and droughts to become more severe.

Increased rainfall may not bring us more water. Land use changes also impact our water resources. Increasing impervious cover from roads, pavement and buildings does two things:
  1.  It reduces the open area for rain and snow to seep into the ground and percolate into the groundwater and.
  2.  The impervious surfaces cause stormwater velocity to increase and the amount of stormwater runoff to increase more the 5 times. The result is Flooding and diminishing groundwater.

Changing land use and increased rainstorm intensity results in flooding. Stormwater runoff increases in quantity and velocity washing away stream banks, flooding roads and buildings carrying fertilizers, oil and grease, and road salt to the Occoquan Reservoir.

Here in the only USGS groundwater well in the rural area you can see both the seasonality of water, but also the slowly falling groundwater level since 2004. Despite extremely high rainfall in the last few years.

Increases in groundwater use and reduction in aquifer recharge can result in the slowly falling water levels that appear to be showing that our groundwater is being used up. This will impact stream flow.

The changing land use impacts the regional hydrology and groundwater recharge so the quantity of available groundwater and streamflow decreases over time.

The Rural Crescent created in 1998 was eliminated in 2022 by the BOCS adoption of the new comprehensive plan.

Despite available tools, Prince William County did not study the impact of the proposed changes to the quality, availability and sustainability water supply as they are required to do under the Comprehensive Plan law. Nor did Prince William County study the impact of the proposed changes to compliance with the WIP III mandated under the Chesapeake Bay TMDL.

Fairfax Water took the unusual step to ask that Prince William County convene the Occoquan Basin Policy Board and oversee a Comprehensive Study of the impacts on water quality and quantity of the planned land use changes in PW Digital Gateway CPA and the 2040 Comprehensive Plan Update before any action is taken. They declined. 

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