Permeable Pavers for the Overlook Pool Parking Lot will Reduce Harmful Run-off

The first step in installing permeable pavers is to create a gravel reservoir to capture the rain water. The pavers will cover the reservoir and rain water will pass through the spaces to be stored in the gravel until it can soak into the ground.

Overlook Community Pool in Bethesda is getting a new look and stormwater management. Work has started on replacing 1,300 square feet of asphalt with permeable pavers so that the rain water can soak into the ground instead of running off the parking lot into the Little Falls creek.

In 2021, LFWA was pleased to received Montgomery County Watershed Restoration and Outreach Program Grant to tackle the problem of stormwater run-off at the Overlook Community Pool. Working with the Overlook Homeowners Association (OHA), the parking lot will be retrofitted so that it can capture stormwater instead of sending it to the creek.

Problem: Too much runoff

Rain water was running off the Overlook pool parking lot into the storm drain system causing down hill flooding and sending toxic chemicals, trash and other pollution directly to the Little Falls creek. The volume and velocity of the storm water run-off is also causing serious erosion on the creek banks. The resulting silting in the Little Falls creek endangers the small creatures who make their homes under and on the rocks at the floor of the creek, making the Little Falls Branch one of the most impaired streams in the County.

Solution: Install Permeable Pavement!

Areas for pavers are shown in green. The pavers were placed on the south end of the lot so that the tree roots would not be disturbed.

Based on the findings and recommendations of a 2017 stormwater management study for the Overlook community done by the Center for Watershed Protection, we worked with the Overlook HOA to determine how to best prevent rain water from escaping from the 9,000 square foot parking lot. The lot is lightly used by pool goers, but is used as a play space by community residents and for community gatherings. There is also a huge willow oak tree at one end whose roots run under the pavement. After a series of community discussions and a survey of community use, it was decided to install permeable pavement to replace some of the asphalt. Permeable pavement are hard surfaces that are designed to allow rain water to soak into the ground while still supporting cars and other vehicles. The parking lot could still be used as a play/gathering area and the pavers would be located along the east and west sides of the lot, avoiding the end with the oak tree so its roots would not be disturbed.

While there are many different types of pervious pavement, interlocking permeable pavers were selected for Overlook based on their price, ease of maintenance, and appearance.

How do Pavers Work?

Permeable pavers are concrete paving blocks that rest on top of an 18-inch deep specially prepared reservoir. The reservoir is filled with layers of different sized gravel. When it rains, the water runs through the spaces between the blocks and is stored in the reservoir until it can soak into the ground. This way, not only is the water prevented from flowing into the storm drain system to the creek, but the chemicals and other pollution are filtered out by the gravel and cleaned up naturally by the soil. This infiltration technique also recharges the ground water replenishing the natural aquifers that our waterways depend on for clean water.

faqs

Can the pavers support rescue vehicles and other heavy trucks? Yes - the pavers are being installed at Overlook are rated for commercial vehicles. That was an important requirement for the contract. They can support long term parking too. In fact, in many places permeable pavers are used specifically for parking areas to distinguish the parking spaces from the road.

Are the pavers handicapped friendly? Yes, the pavers are 100% ADA compliant. The surface should not present any problem.

Do the pavers need any special maintenance? Yes, but not that much! The spaces between the blocks must be blown out from time to time so that they do not become clogged. These spaces are critical to the function of the system and if they are blocked, the water cannot soak into the reservoir. Further, snow from plowing and leaves cannot be stored on the pavers. Again, anything that could cause the pavers to clog should be avoided.

Is there a residential use for pavers? Yes, permeable pavers are perfect for stormwater management on residential properties and can be used for driveways, walkways and patios. Use them to prevent flooding in your own yard, or prevent water from flowing into your basement. Visit https://www.lfwa.org/pervious-pavers to learn about area rebate programs.

The project is made possible by funding from the Montgomery County Water Quality Protection Fund.

Creeks have HIGH levels of E. coli bacteria

Board Member Sara Robinson demonstrating how to take a sample during volunteer training session, July 1.

In a new program designed to inform the public on the safety of the creeks for recreation,  the Little Falls Watershed Alliance is monitoring the bacteria count of the Little Falls and the Willett Branches. On Wednesday, July 7, LFWA monitored the e.coli levels at four locations in the watershed

Two locations passed, two locations failed

Passed:
Little Falls Branch above the Somerset Pool – (217.8 MPN/100mL)
Little Falls Branch in Brookmont – (275.5 MPN/100mL)

Failed:
Little Falls Branch by the second bench below Mass Ave (648.8 MPN/100ml)
Willett Branch below the Bethesda Pool (579.8 MPN/100mL) 

Pass/Fail interpretations are based on Maryland and the District of Columbia's water quality single-sample standards for E. Coli in surface waters.  Water-bodies with E.Coli levels above 410MPN/100mL  are considered unsafe for human recreation.   

We will be testing sites along the two creeks every two weeks between July 7 and September 15.. Results will be posted on our website and on our Facebook page and shared with community list servs.

Visit HERE for more information.

Thank you to our team of trained volunteers for their commitment to this project. Thank you to the Anacostia Riverkeeper for analyzing the samples in their water quality lab and their help in setting up the program.

Volunteers Needed to Monitor Creek

Little Falls Watershed Alliance is excited to announce that we are starting a bacterial monitoring program for the Little Falls and Willett Branches. We will be sampling at three sites to determine bacteria (E. Coli), pH, water temperature, and air temperature in order to provide up-to-date water quality information for residents during the recreational season. The results will be posted on our website and Facebook page for the public to access.

Citizen Scientists Needed

The key to the program is volunteers. We have selected three locations for testing and we need two or three people to adopt a location to do the sampling. The samples MUST be taken Wednesday mornings and they are sent to the Anacostia Riverkeeper’s lab for analysis Wednesday afternoons. All volunteers must attend a short training session.

Please contact us at stormwater@LFWA.org if you are interested in helping out.

why Monitor?

While the water of our creeks is mostly odorless and looks sparkly clear, the creek is one of the most impaired in Montgomery County. As an urban creek, located in a heavily paved area, stormwater run-off carries a toxic mix of chemicals, trash and other pollutants into the creek. Dog poop left on lawns or dropped into the storm drain system pollutes the creek with fecal matter. The storm drain system flows directly to the creek and after it rains, the volume and velocity of the water is so high that it causes considerable erosion and collapse of the creek banks. Further, sewer lines located under the creek are often exposed by the erosion and leak or break. By testing the e coli levels in the creek, we will get an understanding of the extent of fecal pollution and how the fecal count is affected by rain events. Most important, we will be able to advise the public about the safety of the creek for wading and other water activities.

What else do we Monitor?

Benthic Macro-invertebrate Survey: Four times a year since 2016, LFWA has taken a census of the macro-invertebrate life of the creek. We look for diversity of species as well as total number. Using the Benthic Index of Biotic Integrity (BIBI), we are able to grade the health of the creek. Despite having some bio-diversity, our creek consistently rates poor, the lowest grade. Learn about our program HERE.

Salt Monitoring: Winter salting can cause the salinity of creek to rise, making the waters toxic to life. Since 2019, LFWA has participated in the Izaak Walton Salt Watch program. Information is HERE. In the winter of 2020/21, the salt levels spiked to lethal twice after snow storms.

Plant a Tree for Earth Month

One of the most important things you can do for the environment is plant a tree.  Trees provide habitat for 100s of insects, birds and mammals as well as lower the urban heat index, suck up stormwater and release oxygen into the air.  University of Delaware Professor of Entomology and author of Bringing Nature Home, goes further and identifies trees as keystone plants for the food chain.  He writes “Take a keystone native plant like an oak tree. More than 500 types of caterpillars can eat that oak tree. That allows for a more complex and, thus, more stable food web.” https://www.udel.edu/udaily/2020/december/doug-tallamy-native-plants-food-web-insects-birds-survival-earth/

As more and more trees are cut down to allow for development, planting trees private property becomes even more important.  Fortunately, the District of Columbia and Maryland recognize the value of trees and offer several programs for homeowners.

In Montgomery County:

• Free Shade Trees:  Montgomery County will install shade trees and provide aftercare guidance —all for free.  Request a tree at https://treemontgomery.org/request-a-tree/

• Free Buffer Bundle:  The State of Maryland has bundles of saplings for homeowners who live along or near a waterway.  It can even be a drainage ditch.  https://dnr.maryland.gov/forests/Pages/programs/Backyard-Buffer-Program.aspx

• $25 Coupon:  The Marylanders Plant Trees program started in 2009 to encourage citizens and organizations to partner with the State to plant new trees. Citizens can still take advantage of the coupon program to receive $25 off the purchase of a native tree at 86 participating nurseries across the State. Find a participating nursery and print your coupon at https://dnr.maryland.gov/forests/Pages/MarylandersPlantTrees/Introduction.aspx

• Free Saplings for Earth Month:  Montgomery Parks’ Arboriculture division is hosting two free tree seedling giveaways. Attendees will receive a minimum of 2 tree seedlings, one flowering tree and one shade tree. More available upon request while supplies last.  Two locations!

Seedling Giveaway at Black Hill Regional Park
Date: April 10, 2021, Time: 8 am-12 pm, rain or shine, in 15-minute time slots*
Location: Black Hill Regional Park, 20926 Lake Ridge Drive, Boyds, Maryland 20841. This event will be setup in the Shelter J parking area. Follow the posted signs to the event. You must register for a drive-through pick-up time slot by reserving a timed ticket,

Register for a pick-up time: http://mocoparks.org/SeedlingsBlackHill

Seedling Giveaway at Olney Manor Recreational Park|
Date: April 17, 2021, Time: 8 am-12 pm, rain or shine, in 15-minute time slots*
Location: Olney Manor Recreational Park, 16601 Georgia Avenue, Olney, MD 20832. This event will be setup in the Field #1 parking lot area. Follow the posted signs to the event.  You must register for a drive-through pick-up time slot by reserving a timed ticket.

Register for a pick-up time: http://mocoparks.org/SeedlingsOlney

In DC:

• $100 Rebate: Casey's Trees in DC offers up to $100 rebate for each tree you plant in DC.  https://caseytrees.org/resources/tree-rebate/

• Free Trees: The DC government will plant a tree on your property for free in their River Smart Homes program. You can pick from a wide selection of native shade trees and smaller ornamental trees. https://caseytrees.org/plant/residential-planting/

Salt in Creek Reaches Toxic Levels

During the past two months, LFWA volunteers have periodically measured salt concentration levels downstream from the Massachusetts Avenue overpass as part of a national Winter Salt Watch program sponsored by the Izaak Walton League.   On two occasions, February 3rd and February 14th, measured concentrations were near acute toxicity levels for biological life (i.e. macro-invertebrates), which the EPA cautions should not occur more than once during a 3-year period. A “fair” level that animals can tolerate is usually from about 90-150 ppm; anything over over 230 ppm means that the water is toxic at some level to animal and plant life. Over 860 is acute toxicity.

Learn more about our program HERE.

Where Does the Salt come from?

Have you ever wondered what happens to the salt that is spread on the sidewalks, driveways, and roads in our neighborhood during a winter storm?  When it melts or is plowed off, the salt seeps into the groundwater or runs off into local streams and flows into the Potomac River.  While salt helps to melt or prevent the formation of ice and keep these surfaces safe, too much salt, also called chloride-based deicers, damages pavements and inhibits biological life in our streams. Salt is not biodegradable, accumulates over time, and has long-term corrosive effects and environmental impacts. 

In our winter sampling, you can see the effect of salting and winter storms. Both the >600 readings were taken after snow storms. The January 27 reading was done before the storm at a baseline reading. Download the results HERE.

How does this impact the creek?

Salt toxicity is likely to be one reason the Little Falls Branch is currently rated as having poor water quality. At the winter sampling of biological life by out stream monitoring team, not only did were there very few organism, we were also missing the diversity of organisms that are essential to the health of the creek. Results from our recent benthic macro-invertebrate sampling can be found here.

what can you do to prevent salt toxicity?

Salt keeps us safe, but too much salt is a problem. It comes down to spreading the right amount at the right time and sweeping up the excess after a storm.

On your property:

Montgomery County recommends homeowners:

1. Shovel right away - don’t rely on salt to melt the snow.

2. Use salt sparingly - More is not better. When applied properly, it doesn’t take much to get the desired results. 12 ounces (a coffee cup full) will do 10 sidewalk squares or a 20 foot driveway.

3. Sweep up excess after the storm and save it for another day. This saves you money and keeps the unused salt from dissolving and polluting our waterways.

On the streets and public sidewalks:

Sweeping up excess salt is imperative to good salt management. If you notice salt spills, report them by calling 311. The County or DC Government will send someone out to clean them up. If they don’t, let your elected officials know.

2020 Fall Monitoring Little Falls Branch

Stream Team Leader Frank Sanford sampling the Little Falls Branch, October 2020.

Site:

Site 45, Little Falls Branch

Date & Time:

10/09/2020 08:45 AM

Season:

3-FALL

Organisms Found

• 1 Broad-winged Damselflies - Calopterygidae

• 32 Small Minnow Mayfly - Baetidae Baetis

• 36 Common Netspinner Caddisfly - Hydropsychidae

• 9 Midges - Chironomidae

• 6 Aquatic Sowbug - Isopoda

• 5 Planarians/Flatworms - Dugesiidae

• 2 Aquatic Worm - Oligochaeta

• 1 Leech (flat) - Glossiphoniidae

Winter Stream Monitoring Finds Few Macro Organisms

January 11, 2021

LFWA’s Stream Monitoring team went out Saturday, January 9 for their winter monitoring. The weather was beautiful; the results discouraging. The protocol is to just count the first 100 benthic macro-invertebrates organism found. Unfortunately, they were not even able to find half that number.

Frank Sanford, team leader, reports from the field:

Yesterday’s monitoring was very discouraging. We didn’t find the required 100 organisms, only about 40

Here are totals:

Aquatic worms - 3
Aquatic sow bugs - 7
Chironomidae (midges) - 3
Black fly larvae - 3
Crane fly larva- 1
Common net spinners - 16 (caddisfly larvae)
Damselflies larvae - 5

Unfortunately, our creek is rated poor. Using the protocol set by our partner organization, Audubon Naturalist Society, the team searches for benthic macro-invertebrates - the small critters that live on the bottom of the creek or under rocks. These organism are largely the larva form of flying insects you see around waterways. The diversity and number of organisms found help us determine the health of the creek. The organisms are rated by pollution sensitivity and then assigned a score based on the types found. The protocol also mandates that we find at least 100 organisms as the number of organisms is also an indicator of the state of the stream.

Macro-invertebrates from 2021 winter monitoring. From the left: Aquatic worm, caddisfly larvae and sow bug. Photo by Kevin Misener

Damsel Fly larva from 2021 winter monitoring. Photo by Kevin Misener

LFWA monitors four times a year. We also do salt monitoring and keep track of the pH and temperature of the creek. You can see the results from previous monitoring sessions HERE.

Learn about our Stream Team HERE. We are always looking for new members.