The Urbanized Effect on Detention Ponds
Jones, Department of Earth
Many innovative ideas have been proposed and implemented to correct excess stormwater in ever-growing urbanized areas. Fairly simple ways to alleviate stormwater are the development of retention ponds. These detention basins create a permanent pool throughout the year that helps remove sediment and pollutants from excess runoff before entering a stream and control the outflow of water into streams after storms helping to eliminate flooding and regulate runoff. This provides a unique way of not only controlling stormwater through watersheds but also provides an ecologically friendly alternative to high maintenance canals. However, some ponds were not even suggested to be used as detention ponds but were designated over time. This study measures significant water quality difference in three different bodies of water now being used as detention ponds. Three detention basins were tested weekly for pH, hardness, alkalinity, turbidity, and dissolved oxygen saturation. The results show slight differences in water quality between detention basins located in older neighborhoods and ones in recently developed or undeveloped areas. While some tested areas differed, all the detention ponds remain at adequate and healthy levels for aquatic life. The development and design of lakes and ponds with the intent of being used for Detention provide an efficient means to aid in runoff and flooding.
Keywords: detention ponds, urbanization
Detention ponds are one of two types of stormwater ponds commonly constructed. Retention ponds are dry and fill rapidly during a rainfall event gradually releasing water into the watershed until the basin is dry again. Detention ponds are permanent pools and gradually release stormwater through an outlet structure to adjacent surface waters rather than through infiltration into the soils. Detention ponds can be designed as wet or dry. Wet detention ponds are constructed so that the pond bottom is below the seasonal high water table (SHWT) elevation. Dry detention ponds set the pond bottom above the SHWT (Dykehouse 2001).
Although, in theory, detention ponds create an adequate way to balance urban impacts on watersheds, the design must be appropriate to the situation. Poor design will significantly increase a broad range of impacts. These impacts include a loss of habitat by suspended silt smothering organisms, minimal levels of dissolved oxygen, introduction of pathogens such as viruses and bacteria, excessive nutrient levels that can cause an overgrowth of algae, increased temperatures that affect aquatic life, and a degraded aesthetic quality due to litter (Water Environment Federation 1992).
Many new design elements have been proposed
developers are concerned with the maintenance of their detention ponds.
Jordan’s research in 2001 suggests that detention ponds benefit the
There are three lakes that I specifically looked at
their location, their origin, and their surrounding area (Figure 1).
The three lakes include
The area around
The Wynnfield subdivision is a new housing
located off of
Is there a significant measurable difference in turbidity, pH,
dissolved oxygen in the detention ponds found adjacent to older
newer subdivisions, and undeveloped areas in the
Each lake was tested for pH, turbidity, alkalinity, hardness, and dissolved oxygen content to determine whether these elements are high or low compared to the other ponds of different neighborhood concentrations. Water testing took place every Tuesday between the hours of and so to collect samples during the lake’s highest point of dissolved oxygen content. Areas were also monitored during significant rain events which did not occur until the end of testing period. Samples were tested using a LaMotte water quality testing kit used by Alabama Water Watch. Results were entered into Excel.
The pH of water determines the solubility or the amount that can be dissolved in the water and biological availability of nutrients (such as phosphorus, nitrogen, and carbon) and heavy metals (such as lead, copper, cadmium, etc.). No significant differences were found in each lake's pH. All lake’s pH average is 6.5 SIU with the pond at Wynnefield receiving a slightly higher pH than the others. This pH level is in the optimal range for aquatic life.
appearing cloudy or
muddy, is caused by sediment, algae, and
particles suspended in the water. Stormwater
carries soil and debris into detention ponds from the surrounding
Erosion of the pond’s shoreline also contributes to turbidity.
Bottom-feeding fish can cause a lot of turbidity as they stir up the
sediments in search of food. Rooted aquatic plants have a hard time
turbid water and without such plants covering the pond bottom,
sediments are more easily resuspended by
waves (Water Environment Federation 1992). Turbidity was apparently
Hardness is a
measurement of the
concentration of metal ions such as calcium, magnesium, iron, zinc etc, usually acquired as rainwater
rock. In most water it consist mainly of calcium and magnesium salts,
traces of other metals(Water Environment
1992). The hardness for each lake was slightly different. On
Alkalinity refers to
the hardness derived mainly
from carbonate and bicarbonate ions and directly reflects the buffering
capacity of the water. The alkalinity showed similarities to each
The final area tested was dissolved oxygen. Oxygen is essential for
animals and plants. As water moves past their gills, microscopic
oxygen gas in the water, called dissolved oxygen, are
transferred from the water to their blood. Like any other gas
process, the transfer is efficient only above certain concentrations.
words, oxygen can be present in the water, but at too low a
sustain aquatic life. Oxygen also is needed by virtually all algae and
chemical reactions that are important to lake functioning. The results
most significant as seen in Figure 4. Each
had its own distinct DO saturation level (Figure 4). Water
temperatures in all lakes
increased and decreased at the same time during the period. The long
hot, dry weather gradually increase all
water temperature during the testing period. Water temperature directly
DO saturations in that warmer water tends to hold less dissolved
Discussions and Conclusion
It appears that the
detention ponds in the
watershed are able to maintain a healthy life before, during, and after
urbanization. The new detention pond at Wynnefield
appears to be the healthiest. This is mostly due the new building codes
mindful contractors working together to produce healthy ponds that not
control stormwater and pollution but also
and long lasting aquatic life along the watershed. However, maintenance
crucial for the ponds to remain at an excellent range of health. This
when compared to
Overall, detention ponds appear to have a significant impact when regulated and designed properly. New building
flooding of homes while design and outlets provide better coverage and
to recycling water. Other ponds and lakes naturally established should not be altered but should be able to
to the watershed, like
Dykehouse, Terry. “Retention Ponds and Detention Ponds, The Recovery Process”. James Edmunds & Associates, Gainesville FL. Available: http://www.florida-stormwater.org/pdfs/pondsarticle.pdf Accessed: March 3, 2006.
Karen. “The Use of Retention Ponds in Residential
Settings”. University of South Alabama
Department of Earth Sciences,
Collection Systems Design
Subdivision Regulations for the City of
Water Environment Federation. Design and Construction of Urban Stormwater
William, et al. Stormwater
Management in Urbanizing Areas.