CRRP Study – Existing Conditions


Existing aquatic environmental conditions in this reach of the Carp River are described in the Carp River Watershed Study (Robinson Consultants 2003). Relevant information is summarized below.

Stream flows through the summer period in the Carp River are very low often in the order of 50 l/sec in the vicinity of the Village of Carp although the drainage area upstream of this point is nearly 120 sq. km. At the other extreme spring flooding is extensive, because the river flows through a broad, flat floodplain. The floodplain defined by MVCA in this river segment is 200 – 300 m wide, with flooding routinely extending beyond the pastureland along river as shown in Figure 1. Surface water quality conditions are relatively good, however nutrient levels, as typified by total phosphorus are routinely in excess of the PWQO of 0.03 mg/l, indicating moderately eutrophic conditions. These nutrient enriched conditions are made worse by the general lack river flow during the summer season. The combination of low flows and readily available nutrients has led to extensive aquatic plant production in the river, to the point where there is no evidence of a weed free channel.

Land use in the Carp River Watershed is rural with more intensive agriculture concentrated within the broad floodplain of the river. Historically and currently both the tributaries, the main channel and the streamside environments of the Carp River have been extensively modified to improve drainage and facilitate agricultural land use practices. These practices have modified the morphology of the river and altered its sediment load and sediment carrying capacity leading to a number channel adjustments that have contributed to the current degraded condition of aquatic and streamside habitats. Examples of these changes can be seen within the study area and include:

• Straightening and widening of the river, eliminating historic bends and ox-bow meanders;

• Side casting dredged material on the riverbanks, increasing bank heights, disconnecting the river from its floodplain;

• Removing most of the woody and non-woody natural vegetation along the riverbanks;

• Creating a uniform channel, eliminating aquatic habitat features such as pools and riffles;

• Increasing sediment loading to the river from traditional cultivation practices, increasing the amount of fine sediment deposited in the river

The current “bankfull” channel dimensions vary from about 15 –20 m with a current water depth of approximately 15 – 30 cm over a soft clay-muck substrate. In late summer, much of the channel is obstructed by dense, emergent aquatic plant growth, often dominated by cattails. Stream banks are low (in the order of 1 m) and show evidence of trampling by livestock, resulting in slumpage and minor failures. Stream velocities are extremely low, negligible under low flow conditions, particularly where aquatic plants completely cover the channel cross section. Based on the remnant meander features, the old river channel had a meander length of about 200 m and a width of about 160 m and would likely be classified as an “E” type channel (Rosgen 2000).  Existing channel gradient is negligible through the entire study reach. Side casting of material dredged from the channel has created a berm that, once over topped by spring floodwaters, actually retards the recession of floodwaters from adjacent lands thus delaying drying of farmland.

A typical bankfull channel dimension for a natural watercourse with this drainage area should be in the order of 12 m with a depth of about 1 m.

Fish and benthic invertebrates were sampled at a location immediately downstream of the study area. The benthic invertebrate community (aquatic insects, clams, snail, crayfish) that was present is typical of degraded water quality conditions, primarily as a result of high nutrients, low baseflows, poor habitat conditions and periodic low dissolved oxygen conditions. The community received an Ephmeroptera-Plecoptera-Trichoptera (EPT) score of 2 and a Water Quality Index (WQI) score of 4.4 indicating poor water quality.  These indices are based on the various types of aquatic invertebrates present at the site which are given a score based on their relative abundance and general sensitivity to water quality degradation (nutrient enrichment and chemical contamination). The benthic invertebrate community scores (WQI and EPT) may also reflect suspended sediment loading that leads to a reduction in the diversity of habitats for these organisms and may regularly smother existing habitats. The fish community present is a tolerant warm water fish community with a total of 6 species present and an Index of Biotic Integrity (IBI) score of 27, represented by the following:

• Tolerant warmwater fish community: this community includes longnose dace, creek chub, white sucker, common shiner, pumpkinseed, central mudminnow, johnny darter.

The IBI score is similar to the EPT and WQI scores except it is based on the abundance and relative tolerance of fish species. At this location, darters and dace were not present primarily as a result of lack of coarse sediments (sands and gravels) and the paucity of riffles.

The target fish community for this segment of the Carp River is a diverse, moderately tolerant, warmwater community, represented by the following:

• Diverse, moderately tolerant cool/warm water fish community: This community includes rock bass, smallmouth bass, northern pike, walleye (seasonally), redhorse sucker species, a number of sensitive minnow species such as blackchin shiner, blacknose shiner, rosyface shiner, mimic shiner.

While it may not be feasible, except in the long term to restore conditions suitable for all of these species, it is feasible to restore suitable conditions for many of these species, in particular northern pike, smallmouth bass and redhorse suckers. Without a concerted effort to restore both instream and streamside habitats, these species will continue to be restricted to the lower river downstream of Kinburn and some of the tributaries such as Poole, Huntly and Corkery.

There are some minor drainage features that discharge into the Carp River along this segment of the river, however these are intermittent in nature and do not provide fish habitat. They do provide a source of seasonal flow, primarily during springmelt.

There are several old meander features that represent the historic pattern of the river through this reach. Several of these features contain water for much of the year and also appear to be underlain by fine textured, organic substrate of indeterminate depth. There are some large trees, probably willows associated with these remnant features.

Riparian woody vegetation is generally lacking along most the river, except in the vicinity of the old meander features near the south end of the study area and some small areas near the north end of the study area near the Carp Road Bridge. Some springs are reported to occur in this vicinity.

Land Use/Agriculture

There is currently one active farm, located on the southeasterly corner of the study are, and two other properties, one opposite the farm and one northwest of the farm that includes both sides of the river.  The farm includes a farmstead and is an active dairy farm.  The northwest property is used as seasonal pastureland and the property opposite the farm is retired agricultural lands that have been partially planted with trees.

The lands adjacent to the river are used as pasture and are currently limited to unimproved pasture as a result of frequent flooding poor soil conditions (productivity and drainage) and the presence of remnant meander scars from the former path of the river. Livestock are pastured for at least a portion of the year on these lands and livestock have unrestricted use along both sides of the river along all of these three properties.  Livestock occasionally cross the river. Under current conditions, these lands can only be used as marginal pasture.

Other Land Uses

There are a number of older residences along Rivington Street adjacent to the river as well as some newer residences that have recently been built, that are set farther back away from the river. There are a number of storm water management issues associated with runoff from the urban lands along the northeasterly side of the river that may result in nutrient and sediment loading to the river. Some of these lands and associated road drainage enter the river via some open drainage channels.

Recreational use of the river and its banks is limited to private use and current access to the river is very limited, since the riverbanks are relatively steep in the vicinity of the bridges. The river itself is quite shallow and weed-choked in summer making navigation, even by canoe, very difficult. The soft substrates in the river and along its banks also make access difficult if not treacherous, at best.  In general, there are few points where access to the river is feasible within the Village of Carp.

The existing rail line is currently in periodic use, however, ownership will be transferred to the City of Ottawa in the future. Current plans are to use the rail line as part of a recreational trail system linking to communities and features along the river. This trail system is envisioned to include trails along the Carp River as well as making use of some rural roads, and will link up with other existing trails in rural and urban communities.