( wetland and 2.5 to 3 parts per thousan...)Road salt affects mitigation wetlands

Silver has also tested all six wetlands for salinity and looked in bottom sediment for non-biting midge populations because midges are good indicators of stress.

"Last year all the wetlands went back to zero salinity in mid spring," says Silver. "We are not sure if this will continue as we do not know if the baseline will creep up from salt deposited in the sediment."

She does not know if the salt levels will again fall back to zero in mid spring this year as Erie had its last snowfall on May 2 and had a three-foot snowfall in late April.

"PennDOT is between a rock and a hard place," says Silver. "Everyone knows that the salt is not good for the environment, but salting roads is a huge safety issue in a part of the country that gets 10 to 12 feet of snow every winter."

Silver's research does show a large decrease in non-biting midges in the designated runoff wetland. The effect on other species is not yet known. There was no decrease in midges from the slightly salty wetland. In general, freshwater organisms are not very salt tolerant. The Penn State researcher has students poised to look at the numbers and species of algae, amphibians, insects and bacteria in the salty and freshwater wetlands.

"We would like to know how big a hit these two wetlands are going to take from the salt. We see an effect on the midges in the runoff receiving wetland, but so far there is no effect on the slightly salty one," says Silver. "One thing we would like to see is what happens to bullfrog tadpoles and dragonflies that overwinter in the sediment mud."

The researcher would also like to sample the soil where the runoff eventually leaves the wetland to see if salt is building up there.