´╗┐PWCAPrince William Conservation Alliance

´╗┐Community Report, February 9, 2021

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Pond at Merrimac Farm WMA

Vanishing Water? From the Rural Crescent to the Occoquan Reservoir

Great Blue Heron at the Occoquan ReservoirThursday, February 11, 7pm
RSVP required, click here to register

with Elizabeth Ward, author of The Lenders Guide to Developing an Environmental Risk Management Program and the Green Risks blog, with entries such as the following...

Recently, the Prince William County Board of Supervisors approved the development of the Preserve at Long Branch, rezoning a portion of the Rural Crescent. No analysis was done as to the potential impact of this development to the hydrology of the Occoquan Watershed.  There is no understanding what the impact this might have to the sustainability of the drinking water supply of adjacent property well owners and the quality of the Occoquan Reservoir itself. 

The Occoquan Reservoir is an important part of our drinking water supply. The Occoquan supplies about 40% of the clean drinking water for 1.7 million people and, in an emergency, can supply all for a short period of time. The reservoir’s current storage capacity is estimated by ICPRB to be 7.85 billion gallons.

Prince William land accounts for 40% of the Occoquan watershed which contains 1,300 stream miles, Lake Jackson and Lake Manassas as well as the Occoquan Reservoir.  Water from the Occoquan Reservoir is distributed to customers in Fairfax and Prince William Counties. This water is essential. 

Development impacts water quality. Minimizing impervious surface cover and maintaining the tree canopy is critical to the protection of the County’s streams which flow to the Occoquan and other reservoirs. There is a direct correlation between stream health and impervious surface cover and tree canopy.

Impervious surfaces create stormwater runoffAccording to the Northern Virginia Regional Commission, watersheds with impervious surface cover of 10 to 15% show clear signs of degradation, while watersheds with impervious surface cover greater than 25% typically do not support a diverse stream ecology and are dying.

During development the primary impact is erosion and sediment that are carried by stormwater into the streams. The primary post-development impact is increased stormwater volume and velocity that is caused by the removal of tree canopy cover and the replacement of pervious surfaces of plants and grass with the impervious surfaces such as roads, parking lots, rooftops, driveways, patios, etc.

Development increases impervious surface area, and this has created in the past and will in the future create a host of concerns for managing the Occoquan Watershed. For instance, the physical condition of the Watershed's tributaries has been measured to fall with development. Increased stormwater runoff from impervious surfaces flows into streams and creeks at a higher volume and velocity. The result is increased erosion of stream banks that leaves a degraded ecosystem.

The Occoquan Watershed is more than just a source of water for the Reservoir. In addition to its role as an essential portion of the drinking water system for approximately 1.2 million Northern Virginians, the Reservoir and the Watershed also serves to improve water quality:

• The Reservoir is an essential element in meeting the Chesapeake Bay TMDL by trapping sediments and nutrients. According to the Occoquan Watershed Monitoring Lab (OWML) the Reservoir captured 34% of total nitrogen, 56% of total phosphorus, and 83% of total sediment.

• The downzoned portion of the Watershed within Fairfax and the Rural Crescent serve as a natural water treatment system and high quality ecological habitat.

• The Reservoir is a regional recreational asset.

Prince William has ignored its responsibility to best manage the Occoquan watershed in conjunction with Fairfax County’s management of Occoquan Reservoir (and their side of the Watershed) maintaining the primary benefit of the Reservoir as an essential and reliable source of safe, clean drinking water for Prince William County and the importance of the Reservoir as an integrated ecological and hydrological system with multiple uses.

Other Resources:
Occoquan Watershed Report
Occoquan Watershed Documentary Film


BluebirdVolunteer Opportunity: Monitor Bluebird Nests!

Do you enjoy seeing the wonder of nature up close and personal? Join us to officially peek into nesting bluebird houses to see sights not available to all…the building of nests, the laying of eggs, the hatching of eggs sometimes almost right before your eyes! You just never know what you are going to see when you peek into the bird boxes.

The Bluebird Trail at Chinn needs volunteers to monitor from April to Late-August. A training session will be held to teach all new volunteers mid-to-late March. This will also be a great refresher for returning volunteers!

Bluebirds are a dramatic environmental success story and our continued support keeps their population strong.

Thanks to the many people who install and tend nesting boxes Nationwide, Bluebird populations are growing.

It’s important conservation work, and you’ll have a great time too! Each week, you’ll check the nesting boxes and record what you see. All materials are provided. You will only need to commit approximately 4 hours a month.  

This is a great opportunity whether you’re looking for some alone time on the trail or you’re looking for an activity for the entire family. To find out more, fill out this volunteer form here.

Prince William County mapJoin our Facebook Group: The Rural Crescent is That

In light of the mounting pressure to undo to Rural Crescent, we started a Facebook Group to share the beauty, housing diversity, farmland, and overall value that this area brings to the county! This public platform is a place for us to stand together, educate each other, and build a movement to protect and strengthen the Rural Crescent as part of our smart growth plan. Join us and bring your friends! 


Cockpit Point on the Potomac: A Historical Refuge

great blue heronMonday, February 22, 7pm
RSVP required, click here to register

Join PWCA and PWC Historic Preservation Division Manager Rob Orrison for a brief historic overview of the property, current conditions, and a sneak peek preview of some of the plans for the future Cockpit Point Civil War Park.

This approximate 110 acres of undeveloped land along the Potomac River near Dumfries was proffered to PWC by the developer Sun Cal. It is a hidden treasure that includes a large pond, wetlands, river frontage, and the historically significant Cockpit Point battery, along with Civil War campsites.

At the end of the talk, share your thoughts and possible ideas for how this preserved land can best serve our community.

Rob Orrison has authored three books on the Civil War and American Revolution and also serves as the President of the Virginia Association of Museums. He is the Division Manager for the Prince William County Historic Preservation Division of the Department Parks, Rec and Tourism.