From prehistoric times into the late 1800s, Lake Erie and its tributaries maintained a healthy fishery.
Euclid Creek was no exception: In the late 1800s, catfish, crappies, largemouth bass, suckers, sunfish, and shorthead redhorse were all caught on a regular basis in Euclid Creek.
Even the occasional lake sturgeon was found in the creek.
In 1918, anglers were regularly catching catfish, shorthead redhorse, suckers, and yellow perch in Euclid Creek.
Carp were, by then, also extremely common, and the occasional bass could still be found.

Pollution and other impairments led to significant losses in the number and diversity of species by the 1960s.
A 1964 study found that invertebrate species were limited to black flies, crayfish, crane flies, flatworms, leeches, mayflies, snipe flies, and seven species of midge.
The only game fish which remained in the creek were the hogsucker, green sunfish, and white sucker.
Coho salmon and rainbow trout (also known as steelhead) were observed entering the creek, but no spawning occurred.
Pollution-tolerant minnow species were the only small fish to remain.
These included the central stoneroller, common creek chub, common shiner, emerald shiner, and western blacknose dace.
The east branch had a greater diversity of fish than the main branch, but was much less diverse than the nearby Big Creek or Chagrin River.
A 1978 survey found 11 species of frog and toad, 13 species of reptile, and 12 species of salamander in or near Euclid Creek.
The most common reptile was the box turtle.

Pollution impairment of Euclid Creek worsened by 1984.
Water quality was poor in all portions of the stream.
Orthocladiinae (a subspecies of midge) and Oligochaeta (sludgeworms) constituted 65 percent of all fauna collected in or near the stream.
The other invertebrates found in any number included caddisflies, mayflies, and stoneflies.
At a sampling site near the intersection of Green and Anderson Roads, only small numbers of fish were present, and many of these were infected with fungus or were dead.
The east branch of Euclid Creek exhibited the most species diversity of any segment of the stream.
Its lower 2 miles (3.2 km), however, were grossly enriched due to flows from a sewage treatment plant.
Species diversity was about as good in the stream segment encompassed by the Euclid Creek Reservation, although the number of animals was much lower.
This portion of Euclid Creek appeared to be significantly impacted by nonpoint sources.
All fauna in the creek was found to be moderately to highly stressed by pollution.

By the late 20th century, only sucker fish survived in Euclid Creek upstream of its lacustuary, and they vanished by 2000.

Fish populations in Euclid Creek remain impaired, exhibiting low diversity and a high percentage of pollution-tolerant species.
Top-of-the-food-chain predatory fish are absent from the creek, a common indicator of an unhealthy stream habitat.
Above the St. Clair Spillway, fish populations are primarily pollution-tolerant minnows such as the central stoneroller, common creek chub, and western blacknose dace.
Darters are absent, and this limits the capacity of the stream.
Below the spillway, coho salmon, rainbow trout, and smallmouth bass may be found.
Improving the nearshore and lacustuary areas of Euclid Creek are important to increasing the diversity, health, and viability of fish populations in Euclid Creek.
No fish consumption advisories have been issued by the Ohio Department of Health for fish caught in Euclid Creek.

Non-fish macroinvertebrate populations are less impaired than fish in Euclid Creek.
The diversity, health, and number of macroinvertebrates in the lower watershed meet ODNR water quality standards, although this is not true for the upper watershed (upstream of Euclid Creek Reservation).
The macroinvertebrate population is dominated by pollution-tolerant species like midges and worms, with only low levels of caddisfly, mayfly, and stonefly present.
From prehistoric times into the late 1800s, Lake Erie and its tributaries maintained a healthy fishery. Euclid Creek was no exception: In the late 1800s, catfish, crappies, largemouth bass, suckers, sunfish, and shorthead redhorse were all caught on a regular basis in Euclid Creek. Even the occasional lake sturgeon was found in the creek. In 1918, anglers were regularly catching catfish, shorthead redhorse, suckers, and yellow perch in Euclid Creek. Carp were, by then, also extremely common, and the occasional bass could still be found.
Pollution and other impairments led to significant losses in the number and diversity of species by the 1960s. A 1964 study found that invertebrate species were limited to black flies, crayfish, crane flies, flatworms, leeches, mayflies, snipe flies, and seven species of midge. The only game fish which remained in the creek were the hogsucker, green sunfish, and white sucker. Coho salmon and rainbow trout (also known as steelhead) were observed entering the creek, but no spawning occurred. Pollution-tolerant minnow species were the only small fish to remain. These included the central stoneroller, common creek chub, common shiner, emerald shiner, and western blacknose dace. The east branch had a greater diversity of fish than the main branch, but was much less diverse than the nearby Big Creek or Chagrin River. A 1978 survey found 11 species of frog and toad, 13 species of reptile, and 12 species of salamander in or near Euclid Creek. The most common reptile was the box turtle.
Pollution impairment of Euclid Creek worsened by 1984. Water quality was poor in all portions of the stream. Orthocladiinae (a subspecies of midge) and Oligochaeta (sludgeworms) constituted 65 percent of all fauna collected in or near the stream. The other invertebrates found in any number included caddisflies, mayflies, and stoneflies. At a sampling site near the intersection of Green and Anderson Roads, only small numbers of fish were present, and many of these were infected with fungus or were dead. The east branch of Euclid Creek exhibited the most species diversity of any segment of the stream. Its lower 2 miles (3.2 km), however, were grossly enriched due to flows from a sewage treatment plant. Species diversity was about as good in the stream segment encompassed by the Euclid Creek Reservation, although the number of animals was much lower. This portion of Euclid Creek appeared to be significantly impacted by nonpoint sources. All fauna in the creek was found to be moderately to highly stressed by pollution.
By the late 20th century, only sucker fish survived in Euclid Creek upstream of its lacustuary, and they vanished by 2000.
Fish populations in Euclid Creek remain impaired, exhibiting low diversity and a high percentage of pollution-tolerant species. Top-of-the-food-chain predatory fish are absent from the creek, a common indicator of an unhealthy stream habitat. Above the St. Clair Spillway, fish populations are primarily pollution-tolerant minnows such as the central stoneroller, common creek chub, and western blacknose dace. Darters are absent, and this limits the capacity of the stream. Below the spillway, coho salmon, rainbow trout, and smallmouth bass may be found. Improving the nearshore and lacustuary areas of Euclid Creek are important to increasing the diversity, health, and viability of fish populations in Euclid Creek. No fish consumption advisories have been issued by the Ohio Department of Health for fish caught in Euclid Creek.
Non-fish macroinvertebrate populations are less impaired than fish in Euclid Creek. The diversity, health, and number of macroinvertebrates in the lower watershed meet ODNR water quality standards, although this is not true for the upper watershed (upstream of Euclid Creek Reservation). The macroinvertebrate population is dominated by pollution-tolerant species like midges and worms, with only low levels of caddisfly, mayfly, and stonefly present.
Euclid Creek