3. Topics
• What is a watershed? Who cares?
• Major pollutants – nutrients and sediment
• Reedy Creek – poster child for urban
watersheds
• Best Management Practices to protect
water quality – Trees, Trees, Trees
4. CREEK CONNECTIONS
Box 10, Allegheny College, Meadville, PA 16335
http://creekconnections.allegheny.edu
What is a Watershed
5. A Watershed
Definition
• The total land area that
contributes water (or
drains into) a particular
waterway.
• Can also be called a
“Drainage Basin”
6. Flow: Groundwater
Under the surface, GROUNDWATER is on the move
Infiltration or percolation
Source of illustration: http://www.epa.gov/region01/ge/thesite/groundwater.html
7. Flow: Surface Runoff
Surface Runoff can also be called “Overland Flow”
http://h2osparc.wq.ncs
u.edu/info/phos.html
Creek Connections
photograph
http://h2o.enr.state.nc.u
s/nps/What_is_NPS/ur
ban.htm
Over forested land,
fields, grasslands,
even parking lots
Source of illustration: http://www.epa.gov/region01/ge/thesite/groundwater.html
8. Watershed Boundary
Any water within
the boundary of
your watershed or
precipitation that
falls within the
boundary will flow
into your
waterway.
9. Watershed Impacts
• Land and waterway interaction
What we
do on land
affects our
waterways
Source of illustration: http://www.epa.gov/region01/ge/thesite/groundwater.html
10. Watershed Impacts
• Land and waterway interaction
Source of illustration: http://www.epa.gov/region01/ge/thesite/groundwater.html
What YOU
do on land
affects our
waterways
11. Watersheds – Who Cares?
• All land is part of some watershed
• Surface runoff and groundwater carry
pollutants from the land
• Land use determines water quality
12. Major pollutants carried by
stormwater runoff
• Bacteria
• Toxic chemicals –
petroleum, pesticides, herbicides, heavy
metals, PCBs
• Nutrients
• Sediment
13. Nutrients in Aquatic Systems
1. Nitrogen (N)
2. Phosphorous (P)
3. Potassium (K)
14. Nutrients (continued)
-
Eutrophication
Too many nutrients enter aquatic system
Rapid growth of algae (bloom)
Algal population crashes and dies
Microbial decomposition uses up dissolved
oxygen
Fish kills, odors, taste problems in drinking
water sources
18. Sediment
- Injures fish and aquatic
invertebrates
- Carries phosphorous
(nutrients)
- Decreases light penetration
(decreases SAV - Submerged
Aquatic Vegetation)
- Removes bottom habitat by
filling in spaces between rocks
19. Effects of sedimentation
Lots of space between rocks
for aquatic insects and small
fish.
Little space under rocks.
Rocks are “embedded” by
sediment. Terrible
habitat quality.
20. Sediment (continued)
Human Sources
- Stormwater runoff from
urban/suburban areas
- Runoff from construction
sites, agricultural fields, etc.
- Loss of riparian areas and wetlands
- Bank erosion from
channelization/stormwater volume
37. Lawn Facts
1. Lawn covers 9.5% of
the Chesapeake Bay
watershed –
more than all row crops
2. Lawn is often semi-impervious – pathetic topsoil,
compaction, and poor management
40. Lawn Management
1. Mower Height – 3 inches or highest
setting
a. Deeper roots = Healthier lawn
b. Reduced evaporation
2. Mowing Frequency – as little as possible
3. Improve soil with organic matter
a. Grass clippings
b. Mulched or composted leaves
43. Fertilizers
• Soil testing and use of minimal amounts of
fertilizer
• Slow-acting fertilizers are most
environmentally friendly
• Pay attention to the weather – do not
fertilize with fast acting fertilizers
immediately before rain is predicted.
44. Pesticides and Herbicides
• Learn to live with pests – they are part of a
balanced ecosystem
• Hand-weeding and hand-picking pesky
insects can be therapeutic
• Plant something else
• If spray you must: use least toxic, fastest
degrading option and pay attention to the
weather
47. Study Results
• Native plants support
35x more caterpillar
biomass than alien
plants.
• Native plants had
3x more insect species
than alien plants.
48. Native Plant Selection:
Good, Better, Best
Best = Native Plant of Local Ecotype
Local Ecotype: a collection of plants
originating in a specific area and
therefore carrying genetic adaptations
to that specific environment
(Source: Iowa Prairie Network)
http://www.iowaprairienetwork.org/org/Positions/positionlocal_ecotype.shtml
50. BETTER (Next Best)
Wild Native Plant of unknown
geographic origin
OR
Wild native plant of known
geographic origin that is “far”
away
51. Good (?)
Cultivars of Native Plants
Cultivar = Assemblage of plants that
(a) has been selected for a particular
character or combination of characters,
(b) is distinct, uniform and stable in
those characters, and (c) when
propagated by appropriate means,
retains those characters. (Source:
Wikipedia)
52. Cultivar Properties of Concern
1. Genetic diversity is low to non-existent
a. Each plant is genetically identical if it is a clone
propagated asexually (cuttings)
b. Extremely limited genetic diversity if propagated by
inbreeding
2. Unknown if full ecological value is retained. (Seed,
nectar, leaf nutrition, pollinator attractants, etc.)
3. Geographic source often unknown – may not grow well
in local environment
4. If cultivar sexually reproduces with native plants of the
local ecotype it can potentially damage the gene pool
of wild populations, especially if the same cultivar is
planted widely.
54. using
trees
to reduce stormwater runoff
http://www.slideshare.net/watershedprotection/using-trees-to-reducestormwater-runoff-formatted-presentation?type=powerpoint
55. trees are the original “multi-taskers”
save energy
improve air quality
provide habitat
better quality of life
neighborhood stability
aesthetic values
increase property value
reduce noise
good for business
56. Why integrate trees and
stormwater?
• Potential benefits of trees in stormwater treatment
practices: infiltration, pollutant
removal, stabilization, habitat, reduced mowing
costs, landscaping value
• Implementation of stormwater forestry practices has
been limited - lack of collaboration among foresters
and stormwater engineers (and city planners and
transportation engineers and ….
• Use of trees (non-structural practices) is more costeffective than use of structural practices
57. Stormwater forestry opportunities in a
watershed
Opportunities to build urban tree canopy
that can enhance stormwater treatment
and improve watershed health
•
•
•
•
•
•
•
•
•
Schools
Parks
Highway rights-of-way
Vacant lots
Streams and shorelines
Utility corridors
Street medians and roadways
Parking lots
Home lawns (education and incentives are key)
59. Residential landscapes can be functional and beautiful
Use trees to:
block winter winds,
shade summer sun,
accent important views, and
screen private areas
60. Planting along local roads
More shade means more time between repaving. 20% shade on a street improves
pavement condition by 11%, which is a 60% savings for resurfacing over 30 years.
61. Reforesting stream buffers provides stream
shading, bank stabilization, pollutant removal and
other benefits
63. alternative sidewalk design
Traditional sidewalk designs utilize individual tree pits (left)
which confine roots; alternative designs cluster trees
(right), which allows them to share rooting space. This
reduces the need for tree roots to grow under pavement.
72. Watershed Organization Websites
• Alliance for the Chesapeake Bayhttp://allianceforthebay.org/
• Center for Watershed Protection – http://cwp.org/
• Earth Sangha - http://earthsangha.org/
• James River Association http://www.jamesriverassociation.org/
• Reedy Creek Coalition – http://reedycreekcoalition.org/
• Rivanna River Streamwatch - http://streamwatch.org/
In a forested watershed with minimal human impact, over 90% of the rainwater that falls on the watershed infiltrates into the ground. In many urban watersheds, over half of the rainfall enters the nearby stream and very quickly. This is because much of the land is covered by impervious surfaces that prevent water from infiltrating into the ground.
Much of urban runoff should have infiltrated into the ground and replenished the groundwater. This loss is critical because it is groundwater that allows a stream to keep flowing during dry weather. Without groundwater, small streams dry up in the summer and prevent survival of aquatic animals such as insects and fish.Agricultural fields and lawns tend to be semi-impervious – that is some water can infiltrate but there is not near as much infiltration as compared to a forest or even a meadow.
The term watershed can refer to a very small land area (on the order of acres) or to a very large area such as the Chesapeake Bay watershed which is over 64,000 square miles.
Point source pollution comes from a localized site such as an industrial facility or wastewater treatment plant. It usually enters the stream as discharge from a pipe. Point source discharges are regulated by Virginia DEQ and require a permit.
Nonpoint source pollution comes from a large area and usually enters a stream all along its length. Agricultural fields, lawns, and roads are examples of nonpoint sources of pollution.
Anything on the land can be picked up by stormwater and carried to the nearest stream. Also, chemicals that dissolve easily in water can be carried down into the groundwater and enter streams years later.
This picture shows eutrophication due to the explosive growth of phytoplankton. Phytoplankton is free-floating algae that can reach very high densities in slow moving waters like lakes, tidal rivers, and the Chesapeake Bay. When you hear about algal blooms in the James River and Chesapeake Bay, they are due to phytoplankton.
The picture on the left shows a sucker that obtains much of its food from scraping the thin, slimy layer of algae off the rocks. There are also a variety of aquatic insects and snails that also eat the thin layer of algae off rocks. On the right, excess nutrients have promoted growth of nuisance, filamentous algae. The nuisance algae is not a food source for fish or macroinvertebrates and by covering the rocks it blocks the growth of the “good” algae. In addition, the nuisance algae blocks access to the nooks and crannies between rocks that small fish and macroinvertebrates use to hide from predators. As a result, a large growth of nuisance algae due to excess nutrients greatly alters the local ecology/food web.
Riparian areas are the last line of defense from nonpoint source pollution. A wide, forested riparian area can greatly reduce the negative impacts of nutrients from areas further away from the stream.It is estimated that about 30% of the nitrogen that reaches the Chesapeake Bay is from air deposition. This is the nitrogen released from burning fossil fuels. So saving money by reducing energy usage is helping to “Save the Bay”.Wastewater treatment plants have been steadily decreasing the amount of nutrients discharged to surface waters through mandatory adoption of new technologies.
The upper picture shows sediment-laden runoff from a construction site after a large rain. Most of the erosion and sediment control fences around the site were in good shape – but it only takes one small damaged area of sediment controls to create a huge pollution problem. For a fish or aquatic insect trying to get oxygen from the water, it must be like humans trying to breathe diesel exhaust.Beds of SAV are like underwater meadows and provide critical nursery habitat for blue crabs and lots of juvenile fish. The current acreage of SAV in the Bay is estimated to be about 10% of its original coverage. Part of the decrease in SAV beds is attributed to loss of light penetration due to suspended sediment.
Erosion of stream channels can contribute as much as 50% of the total sediment in a stream. This in-stream erosion is usually the result of too much stormwater entering the stream.
Although Reedy Creek is less than four miles long, it includes a remarkable variety of habitats. Clockwise from top left: channel in the “headwaters” of Reedy Creek above the mitigation wetland, mitigation wetland constructed about 15 years ago, section of concrete channel that covers nearly 1/3 of Reedy Creek, Forest Hill Park Lake prior to dredging about 5 years ago, steep section of Reedy Creek between Forest Hill Avenue and the lake, natural section of Reedy Creek below the concrete channel. The channel in this latter section of Reedy Creek has been extensively widened due to erosion of the banks by stormwater.
Trash from roads and neighborhoods throughout the watershed gets washed down storm drains and travels into the creek. Much of the trash collects in large deposits in floodplain areas and Forest Hill Park Lake.
Each blue dot on the plate represents one cell of a fecal bacterium in a water sample. To pass the Virginia water quality standards, there would have to be less than 10 blue dots on this plate and there are over 1,000. This sample came from a bacterial “hotspot” in Reedy Creek. Part of the problem was later found to be a leaky sanitary sewer pipe which has been fixed.
A huge amount of filamentous algae fills the Reedy creek channel during the summer due to the combination of excess nutrients and lack of shade.
Huge sediment bars have formed at various points along the Reedy Creek channel. Bars this large are a clear indication of high stormwater flows carrying sediment. The lack of vegetation on the bar means the sediment is very unstable. During each significant rain event, sediment from the bar is scoured away and replaced with sediment from upstream. This cycle prevents vegetation from being able to take root on the bar and this constant movement of large amounts of sediment downstream is what fills in Forest Hill Park Lake.
The animal on the left is a “midge” larva. Midge larvae are generally very tolerant of pollution. The animal on the right is a lunged snail. Lunged snails are also tolerant of pollution because they can get the oxygen they need for survival by breathing air. Midges, lunged snails, and worms are among the most frequent aquatic macroinvertebrates found in Reedy Creek.
Clockwise from the top left are: mayfly, giant stonefly, stonefly, caddisfly in case. Mayflies, stoneflies, and caddisflies are mostly sensitive to pollution and are commonly found in healthy streams. Reedy Creek sometimes has one type of mayfly that is partially tolerant of pollution. We have never observed a stonefly in Reedy Creek.
This picture shows Midlothian Turnpike before the recent “upgrades”. Note the yellow gauge that was installed to let motorists know how deep the water rose during rain events.
Concrete channels cut off Reedy Creek from its floodplain. All the stormwater that gushes into Reedy Creek is “trapped” in the channel. To make matters worse, the concrete channels are also much straighter than a natural stream channel which has bends to help reduce the speed and energy of the water. By the time stormwater leaves the concrete channels and enters a natural section of Reedy Creek the erosive power of the water can be extremely damaging.
Here is a section of natural channel downstream of the major section of concrete channel. The power of the stormwater trapped in the concrete channel has been unleashed. The eroded bank is approximately 5 feet high above the bedrock in the foreground. Being a fish or macroinvertebrate in Reedy Creek must be like trying to live where a Class 5 Hurricane comes crashing through every month or two.
Reedy Creek like many urban and suburban streams is in rough shape – but it need not be terminal!
IBI = Index of Biotic Integrity. One can think of an IBI score as a direct measure of ecosystem health with a high score being good and a low score being bad. Each point on the graph represents the IBI score for a different stream in Fairfax County. The red line is the “best fit” line through the points and it shows that ecosystem health (IBI scores) steadily declines as the amount of impervious surface in the watershed increases.The red line represents decades of development and land use decisions without understanding the consequences for local streams. The challenge is start undoing the damage by implementing Low-Impact Development (LID) techniques and Best-Management Practices (BMPs) to reduce stormwater volume and pollutant levels. Planting native trees is probably the single most cost-effective BMP.
Rain barrels and cisterns are ideal for gathering water from impervious rooftops to use later for watering trees, vegetable gardens, and other landscape plantings.Rain from impervious surfaces as well as semi-impervious lawn can be directed into rain gardens and Bayscapes designed to provide extra infiltration. Trees are excellent for infiltration because of their deep root systems.
Poor management of lawns includes practices such as over-fertilizing with chemical fertilizers; bagging grass clippings instead of leaving them behind to build soil; and scalping the lawn way too low. Good management practices include getting a soil test to know how much fertilizer to add and then using organic fertilizers; cutting the grass with the highest mower setting (preferably about 3 inches) to promote deeper root development and moisture retention; and leaving the grass clippings on the lawn to decompose and improve the soil.
Turf grasses (shown on the far left of the diagram) have very shallow root systems that only extend a few inches into the ground. By comparison, native perennials and native grasses have very deep root systems that can extend many feet into the soil. Due to their deep roots, native plants provide pathways for deep infiltration of rain water and seldom need watering or fertilization once they are established.
Which cul de sac is doing a better job of infiltrating stormwater? Which one is more inviting and visually appealing?
This slide and the several slides that follow demonstrate a very important concept. For many, many years we have been designing streets completely backwards with regard to stormwater. The typical street design in Richmond (and virtually everywhere) has vegetated strips along the road that are above the level of the road. All of the rain thathits the road is directed into a storm drain and into a nearby creek. In the design shown above, the vegetated strip between the road and sidewalk is lower than the level of the street and there are curb cuts that allow stormwater from the street to infiltrate into these vegetated strips. This is a simple concept that can greatly reduce runoff. Check out 9th Street along the Capitol for a local example of this approach.
By using deep planting wells with soils that are highly efficient at infiltration, it is possible to handle most of the stormwater runoff from a road during a typical rain event.
This picture shows a traffic “calming” structure similar to those that have popped up in Richmond over the last several years (Elwood, Midlothian, etc). In this design, stormwater controls have been built into the traffic project through the use of curb cuts and vegetated strips that are below street level. We need more of this integrated approach.
These pictures show an alternative to traditional curb and gutter that works together with the basic topography of the area.