Stimulate Your Census!

Each week, rain or shine, our dedicated StreamKeepers grab their supplies and make a visit to various sampling sites along the waterways of Lower Merion. Some StreamKeepers sample the stretch of the East Branch of Indian Creek that meanders through Shortridge Memorial Park, the stretch of Valley Stream in Merion Botanical Mark, or Mill Creek as it snakes through the woods of the historic Harriton House property.

Census 3.03 crane fly larvae

A crane fly larvae found during the Stream Census

Our StreamKeepers come from backgrounds that are as varied as our sampling sites, from the students at Bala Cynwyd Middle School that sample Gulley Run in Belmont Mills, to the young professionals and retired professionals that make their way to Indian Creek and Mill Creek in Wynnewood and Penn Valley. In addition to our field sampling, we also have another equally dedicated team of volunteers that work each work out of our Norah Goldfine Bug Lab here at the Conservancy Cottage. Week in and week out, these volunteers spend their time and energy (with the occasional boost of support from our coffee machine) sorting and identifying thousands of aquatic insects that are collected from Mill Creek each spring. Despite the diversity of our StreamKeepers, we all work together to achieve the same goal – combating stormwater runoff and protecting our waterways. In addition to collecting basic water quality samples, StreamKeepers also measure the width and flow of our streams. This data has revealed that our waterways our degrading at alarming rates.


Volunteers preforming chemical tests

The increase in the volume of stormwater runoff has had a drastic impact on our streams. Whether it’s increased chloride levels during the winter road salt season or increased nitrates during the spring lawn fertilizer season, we are able to draw conclusions based on the data our StreamKeepers collect. As stormwater runoff carries these chemicals to our streams during storms, they can cause long-term damage to the stream ecology. Furthermore, stormwater runoff is transported to our streams at an extremely high volume during a short period of time following storms. This rush of stormwater runoff raises the water temperature, which reduces the amount of oxygen available to fish and other aquatic organisms. Also, heavy flows of stormwater runoff causes serious streambank erosion, which destroys both streambank habitat for plants and wildlife and also in-stream habitat for the aquatic organisms that call these streams home. Each spring for the last twenty years, we have collected samples of macroinvertebrates from the same four sites along Mill Creek. Different species of macroinvertebrates have different tolerances to stream pollution, so by analyzing the size, diversity, and richness of the macroinvertebrate population, we are able to determine the biological health of Mill Creek. Unfortunately, its health is rapidly declining.

Due to the increase in stormwater runoff over the last several decades, Mill Creek has received more polluted stormwater runoff than ever before, experienced increased rates of streambank erosion, and has seen an overall decline in stream health. Next Saturday, March 22nd, at 9 AM, Conservancy staff and volunteers will meet at West Mill Creek Park in Penn Valley to conduct the 20th Annual Stream Census. If you are concerned about the health of our streams and want to make a difference in improving the quality of life in Lower Merion, please join us next Saturday and lend a helping hand.


2013 Steam Census volunteers

If you are interested in becoming a permanent StreamKeeper, please contact or call 610-645-9030.

No training or previous experience is required for our Stream Census or to become a StreamKeeper.